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Revision of the Fire Ants of the Solenopsis saevissima Species-
Group (Hymenoptera: Formicidae)
Author(s): James P. Pitts, Gabriela P. Camacho, Dietrich Gotzek, Joseph V.
Mchugh and Kenneth G. Ross
Source: Proceedings of the Entomological Society of Washington,
120(2):308-411.
Published By: Entomological Society of Washington
https://doi.org/10.4289/0013-8797.120.2.308
URL: http://www.bioone.org/doi/full/10.4289/0013-8797.120.2.308
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PROC. ENTOMOL. SOC. WASH.
120(2), 2018, pp. 308–411
REVISION OF THE FIRE ANTS OF THE SOLENOPSIS SAEVISSIMA
SPECIES–GROUP (HYMENOPTERA: FORMICIDAE)
urn:lsid:zoobank.org:pub:F387D696-11D6-4649-A9BC-82D8344F0764
JAMES P. PITTS, GABRIELA P. CAMACHO, DIETRICH GOTZEK, JOSEPH V. MCHUGH,
AND KENNETH G. ROSS
(JPP) Department of Biology, Utah State University, UT 84326 USA (e-mail: james.
pitts@usu.edu); Department of Entomology, University of Georgia, Athens, GA 30602
USA; (GPC) Programa de Po´s-Graduac¸a˜o em Entomologia, Departamento de Zoologia,
Universidade Federal do Parana´, Curitiba, Parana´ 81531-990 Brazil (e-mail: gabieco.
camacho@gmail.com); Department of Entomology, National Museum of Natural
History, Smithsonian Institution, Washington, DC 20013 USA; (DG) Department of
Entomology, National Museum of Natural History, Smithsonian Institution,Washington,
DC 20013 USA (e-mail: gotzekd@si.edu); (JVM) Department of Entomology,
University of Georgia, Athens, GA 30602 USA (e-mail: mchugh.jv@gmail.com); and
(KGR) Department of Entomology, University of Georgia, Athens, GA 30602 USA
(corresponding author, e-mail: kenross@uga.edu)
urn:lsid:zoobank.org:author:89B4EC38-0687-4650-9F0E-AF2324459E10
urn:lsid:zoobank.org:author:9E0ECF1A-5F0F-496B-865B-33EBCF9721A7
urn:lsid:zoobank.org:author:AAD26B8C-D864-4CAD-AB19-ED2637179F58
urn:lsid:zoobank.org:author:9CA20153-0D9B-4839-A3EA-B02AC2F5CBB3
urn:lsid:zoobank.org:author:58B33294-7A7A-4012-BCE0-9AEFAAB3B0F8
Abstract.—The fire ants of the Solenopsis geminata species-group of Trager (1991) are
revised based on the morphology of worker larvae and of adult forms of workers, males,
and gynes (winged or dealated members of the queen caste). The amount of intraspecific
variation occurring in the adult males and gynes was equivalent to that of workers, making
the taxonomic information gained from these castes no better than information from the
workers. A new species, S. metallica, is described from southern Brazil, based on adult
workers, adult gynes, males, and worker larvae. The following classification changes are
made: S. virulens is placed in the S. virulens species-group; S. tridens and S. substituta are
placed in the S. tridens species-group; S. metallica new species, S. daguerrei, S. electra, S.
hostilis, S. interrupta, S. invicta, S. macdonaghi, S. megergates, S. pusillignis, S. pythia, S.
quinquecuspis, S. richteri, S. saevissima, and S. weyrauchi are placed in the S. saevissima
species-group; and S. geminata, S. xyloni, S. amblychila, S. aurea, S. gayi, and S. bruesi are
left in the S. geminata species-group. The older classification, which designated complexes
and subcomplexes, is abandoned. For the S. saevissima species-group, adults of males and
gynes, as well as worker larvae, are described and diagnosed for each species. Diagnoses
and keys (dichotomous and tabular) are provided for adult workers, the most commonly
collected material, and distributions of the species are summarized.
Key Words: fire ants, red imported fire ant, black imported fire ant, Solenopsis
geminata species-group, Myrmicinae, Solenopsidini
DOI: 10.4289/0013-8797.120.2.308
Fire ants are placed in the genus Sol-
enopsis Westwood (Hymenoptera: For-
micidae) in the subfamily Myrmicinae.
There are approximately 190 described
species of Solenopsis worldwide (Bolton
1995). Most of these species are charac-
terized by small, monomorphic workers
that form small colonies and can display
a lestobiotic lifestyle, living in the nest
walls of other ant species from which
they steal food and brood (Thompson
1980, 1989; Pacheco and Mackay 2013).
These habits have earned such Solenopsis
species the name “thief ants.” A smaller
group composed of five species of
Solenopsis are considered inquiline social
parasites of other ant species. These in-
quiline social parasites live alongside the
host queen, generally lack a worker caste,
and their brood is made up only of sex-
uals (Buschinger 2009). Among the re-
maining Solenopsis are 20 New World
species that differ greatly from the thief
ants and social parasites in their biology.
These species have larger, polymorphic
workers, form enormously populous col-
onies, and are highly aggressive in their
foraging and defensive habits. The pain-
ful sting wielded by the workers has
earned such Solenopsis species the name
“fire ants.” Most fire ant species are
Neotropical, although five species are
native to North America (Chialvo et al.
2018). One of these (Solenopsis geminata
(Fabricius), the tropical fire ant) and two
of the Neotropical species (S. invicta
Buren, the red imported fire ant, and
Solenopsis richteri Forel, the black im-
ported fire ant) have been inadvertently
introduced to locations far from their
native ranges. Solenopsis geminata has
been introduced throughout the tropics
worldwide (Wetterer 2011, Gotzek et al.
2015), S. invicta has been introduced to
the United States and several other Pacific
Rim countries (Lofgren 1986, Callcott
and Collins 1996, Henshaw et al. 2005,
Ascunce et al. 2011, Wetterer 2013), and
S. richteri has been introduced to the
United States (Lofgren 1986).
Solenopsis invicta and S. richteri have
become economically important pests in
the United States, where they invade
lawns, pastures, and roadsides, attacking
and stinging native animals, livestock,
and humans when colonies are dis-
turbed, and evidently out-competing
native ants for food and nesting habitat
(Lofgren et al. 1975, Jouvenaz 1990,
Guillebeau et al. 2002, Tschinkel 2006).
Annual economic losses in the United
States attributable to the imported fire
ants are estimated at $6 billion (Lard
et al. 2006). Although the pugnacious
nature of these exotic ants makes them
undesirable inhabitants of areas that they
have newly colonized, they nonetheless
have become premier objects of study
for ecologists and evolutionary bi-
ologists. For instance, fire ants offer one
of relatively few well-documented cases
of the formation of a hybrid zone in
historical times (Vander Meer et al.
1985, Ross et al. 1987a, Shoemaker et al.
1996), which makes them a rich source
of information for genetic studies of
speciation (Baack and Rieseberg 2007,
Nolte and Tautz 2010). Fire ants also
show variation in the social organization
of their colonies, some of which appears
to be under simple genetic control
(Krieger and Ross 2002, Wang et al.
VOLUME 120, NUMBER 2 309
2013), making them important model
systems in the study of social evolution
(Gotzek and Ross 2007, Smith et al. 2008,
Robinson et al. 2008, Fischman et al. 2011).
The flexibility demonstrated by some species
in having either a single egg-laying gyne
(monogyny) or multiple egg-laying gynes
(polygyny) in a single colony has sparked
comparative ecological and evolutionary
studies about the causes and consequences
of such variation (Vargo and Fletcher 1987,
Ross and Keller 1995, Porter et al. 1997,
Gotzek and Ross 2007, Huang and Wang
2014). Solenopsis also includes several so-
cial parasites that use various ant species as
their hosts (Calcaterra et al. 2000, Davis
and Deyrup 2006, Deyrup and Prusak
2008), a characteristic that is of great in-
terest for studies of social evolution as well
as integrated pest management. It is re-
markable that in spite of the extensive re-
search conducted on fire ants, no thorough
taxonomic treatment or phylogenetic anal-
ysis of the group has been conducted. Only
three phylogenetic analyses have been
published, one based on morphology (Pitts
et al. 2005), another using mitochondrial
DNA (Shoemaker et al. 2006), and the third
based on nuclear allozyme markers (Ross
and Trager 1990). All suffer from limited
taxon and/or character sampling and the
appearance of poorly supported clades.
Historically, Solenopsis has been a tax-
onomically difficult group (Creighton
1930, 1950; Wilson 1952; Buren 1972;
Trager 1991; Pacheco and Mackay 2013).
In South America, where species diversity
is highest, distinguishing Solenopsis spe-
cies is exceedingly difficult due to a pau-
city of reliable characters that are constant
within putative species yet differ between
them. Frustration with this situation
prompted Carlo Emery to call the group
the crux myrmecologorum (Creighton
1930) and led Wilson (1952) to propose
several synonymies, reducing the number
of fire ant species to only three. Wilson
apparently believed that the South Ameri-
can fire ants comprise nothing more than
a large hybrid swarm of unstable variants.
Further complicating matters is the fact
that several of the species in North Amer-
ica (both native and introduced) hybridize
extensively where their ranges overlap
(Shoemaker et al. 1996, Helms Cahan and
Vinson 2003, Ross and Shoemaker 2005).
Although the fire ants as a group have
been revised fairly recently (Trager 1991),
some unresolved taxonomic problems re-
main. Thus, we undertook a systematic
study with several specific objectives in
mind. The first was to develop additional
morphological character systems to aid in
the definition and identification of fire ant
species by evaluating life stages and castes
other than adult workers. Data from the
diverse morphological character systems
developed for this study also were used to
produce a phylogenetic hypothesis for the
S. saevissima species-group (Pitts et al.
2005). The second objective was to revise
the classification of the fire ants fol-
lowing cladistic methodology, whereby
only monophyletic groups are designated
(sensu Pitts et al. 2005).
We acknowledge the limitations of a
purely morphological approach in such
a complex and intractable group. It is evi-
dent that our current morphological analyses
capture only part of the (genetically) di-
agnosable diversity of the group (Ross and
Trager 1990; Ross et al. 2007, 2010), and
thus our results almost certainly represent
a lower limit to the actual number of species.
However, taxonomically and geographically
restricted genetic approaches, while un-
covering cryptic diversity within a few
nominal species (nominal S. richteri, S. in-
victa, and S. saevissima), have confirmed the
distinctiveness of the current morphologi-
cally recognized species (Ross and Trager
1990; Ross et al. 2007, 2010; Shoemaker
et al. 2006). We caution against the over-
interpretation of single locus datasets
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON310
(Shoemaker et al. 2006, Gotzek et al. 2007),
which can be construed to suggest that some
morphologically diagnosed species are not
monophyletic and hence not “real” entities.
Instead, we suggest using the multi-species
coalescent accommodating incomplete lin-
eage sorting and hybridization (Fujita et al.
2012) as a better model to understand ge-
netic patterns in fire ants. We consider our
morphological species concept a necessary,
important, and invaluably practical first step
to continued systematic efforts, which will
ultimately require iterative and highly in-
tegrative taxonomic approaches and datasets
to be utilized to test, refine, and correct our
current morphological understanding of
species limits in fire ants.
Taxonomic history of Solenopsis.—
Westwood described the genus Solenopsis
in 1840 for the type species, S. geminata.
Creighton (1930) revised the genus and di-
vided it into five subgenera, Diagyne Sant-
schi, Diplorhoptrum Mayr, Euophthalma
Creighton, Oedaleocerus Creighton, and
Solenopsis. The subgenus Solenopsis in-
cluded the typical polymorphic fire ants,
with the other four subgenera considered
the thief ants. Creighton’s revision included
all Solenopsis species except for those in the
subgenus Diplorhoptrum, which is a large
portion of the genus and, to date, these
species have not been revised. Creighton
based the delineation between the thief ant
subgenera mostly on morphology of the
gynes. Unfortunately, gynes were unavail-
able for many of the species included in his
study and many remain unknown. There
also are cases where the gynes differ sub-
stantially between certain species but the
workers of these same species do not, and
social parasitism cannot be ruled out. In
light of these problems, it is undesirable to
have a subgeneric classification that is based
primarily on the gyne caste.
Ettershank (1966) realized these prob-
lems and synonymized the five sub-
genera. He also synonymized the related
“satellite” genera Lilidris Kusnezov 1958,
Bisolenopsis Kusnezov 1953, Labauchena
Santschi 1930, and Paranamyrma
Kusnezov 1953 under Solenopsis, but
gave little explanation for this decision.
He recognized three “natural” groups in
Solenopsis: the fire ants, the social para-
sites, and the thief ants. The fire ants
comprised species previously placed in
the subgenus Solenopsis, the social par-
asites were species from the genera
Labauchena and Paranamyrma, and the
thief ants were species of all the other
synonymized genera and subgenera.
Some higher-level taxonomic work has
been done on Solenopsis since Ettershank.
Baroni-Urbani (1968) resurrected the
subgenusDiplorhoptrum and elevated it to
the generic level, placing all thief ants in
this genus. He based his decision on the
genitalia of the common European spe-
cies, S. fugax (Latreille), without knowl-
edge of the New World thief ant fauna.
Bolton (1987) presented arguments re-
futing Baroni-Urbani’s decision as well as
supporting Ettershank’s (1966) other syn-
onymies, and again made Diplorhoptrum
a junior synonym of Solenopsis.
The thief ants in Diplorhoptrum were
separated into five species-groups by
Creighton (1930). This system was
abandoned shortly afterward due to
various shortcomings. For instance, the
relationships of the species-groups were
never resolved, and many recognized
species were never placed in one of
Creighton’s species-groups. The most
serious problem, however, was that
subspecies sometimes were classified in
different species-groups than their con-
specifics. More recently, Trager (1991)
placed all species of the old subgenus
Diplorhoptrum in a single, informal
species-group called the S. fugax group,
but the justification for this change was
unclear. He also discussed a S. tenuis
subcomplex, which presumably belongs
VOLUME 120, NUMBER 2 311
in the S. fugax group, however, he did
not specify which taxa belonged in the
new subcomplex. Based on Trager’s
discussion of these new groups, one can
only surmise that the S. fugax group
was to contain other subcomplexes as
well.
Moreno-Gonzalez (2001) treated the
North American species of Diplorhop-
trum and suggested many species-group
changes. She resurrected Creighton’s
S. azteca species complex (sp. com.),
and rearranged his remaining species
complexes by placing the S. laeviceps
and S. basalis-tenuis species complexes
in the S. molesta sp. com. She placed
Creighton’s S. westwoodi sp. com. in the
S. fugax sp. com. of Trager. However, as
discussed above, Trager’s S. fugax
sp. com. presumably already contained
all thief ants, so we must assume that she
intended to place this group in the
S. fugax subcomplex, which was left
undefined by Trager. Moreno-Gonzalez
(2001) also erected a new species com-
plex for S. succinea—previously the sole
member of the subgenus Diagyne—
called the S. succinea sp. com. and
erected the S. minutissima sp. com. to
contain several species, described and
undescribed, that were not treated by
Creighton. She suggested that the spe-
cies previously placed in Euophthalma
should be split into two groups, the S.
globularia sp. com. and the S. nigella sp.
com., based on morphology of the
postpetiole.
More recently, building on Moreno-
Gonzalez’ work, Pacheco and Mackay
(2013) recognized eight species com-
plexes in their monographic revision of
New World Solenopsis (excluding the
fire ants). While they retained Moreno-
Gonzalez’ S. fugax, S. nigella, and S.
globularia sp. com., they expanded her
S. molesta sp. com. to include Creighton’s
subgenus Oedaleocerus, subsumed the
S. succinea sp. com. within the newly
erected S. wasmanni sp. com., further
recognized a S. stricta sp. com., and
renamed the S. azteca and S. minu-
tissima sp. com. as the S. brevicornis
and S. pygmaea sp. com., respectively.
Pacheco and Mackay further synony-
mized Carebarella with Solenopsis,
which was subsequently supported by
molecular phylogenetic analyses (Ward
et al. 2015).
Compared to the New World, the Old
World Solenopsis fauna has received
much less attention. Galkowski et al.
(2010) recognized four ‘morphological’
groups in France: the S. fugax, S. debil-
ior, S. lusitanica, and S. orbula groups. It
is not clear whether their concept of the
S. fugax complex matches that of Pa-
checo and Mackay (2013) and Moreno-
Gonzalez (2001) because the works do
not reference each other. However, some
concordance is expected given that Pacheco
and Mackay explicitly state a morpho-
logical similarity between members of the
New World S. fugax species complex and
the Holarctic species S. fugax.
Recent molecular phylogenetic ana-
lyses confirm the placement of Sol-
enopsis in the tribe Solenopsidini, its
senior synonymy status with Care-
barella, and identify its sister clade to be
composed of Tropidomyrmex and Kemp-
fidris (Ward et al. 2015), thus disproving
previous earlier hypotheses aligning it
with Oxyepoecus Santschi (Ettershank
1966, Bolton 1987).
The fire ants have been treated taxo-
nomically several times (e.g., Creighton
1930, Wilson 1952, Buren 1972). In the
latest revision, Trager (1991) grouped all
of the fire ant species in the Solenopsis
geminata species-group. Trager con-
firmed that all satellite genera, except
Lilidris, were synonymous with Sol-
enopsis, reaffirming Ettershank’s syn-
onymies. His treatment differed from
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON312
Ettershank’s in proposing two indepen-
dent derivations of social parasitism
(in the former genera Labauchena and
Paranamyrma) rather than a single ori-
gin within Solenopsis. Trager’s revision
included the four North American spe-
cies, two hybrids, and 17 species from
South America, three of which were
described as new. One of these species,
S. virulens, Trager considered not a true
member of the fire ants, which would
render his S. geminata species-group
paraphyletic. This species was also no-
tably ignored by Moreno-Gonzalez
(2001) and Pacheco and Mackay (2013).
The species that Trager recognized were
distinctive both morphologically and
genetically (Ross and Trager 1990), but
several studies using genetic data have
further complicated the problematic
alpha-taxonomy of fire ants by suggest-
ing the presence of cryptic species (Ross
and Shoemaker 2005; Ross and Trager
1990; Ross et al. 2007, 2010; Chialvo
et al. 2018).
The Solenopsis social parasites.—
Because Labauchena and Paranamyrma
were synonymized under Solenopsis
(Ettershank 1966), Solenopsis now in-
cludes several species of social parasites.
Two of these, S. daguerrei Santschi
and S. hostilis Borgmeier, parasitize fire
ants, whereas S. solenopsidis Kusnezov
parasitizes thief ants (formerly Para-
namyrma; Santschi 1930, Kusnezov
1954, Borgmeier 1959), and S. phoretica
Davis and Deyrup and S. enigmatica
Deyrup and Prusak parasitize Pheidole
Westwood. The social parasites lead
an especially interesting life style when
compared to other Solenopsis species,
because the parasitic gyne enters a het-
erospecific colony and usurps the re-
productive role of the host queen, rather
than initiating her own colony or joining
a conspecific one (as in the case of
polygyne fire ants).
Solenopsis daguerrei, S. solenopsidis
and, perhaps, S. hostilis exhibit perma-
nent social parasitism. Solenopsis da-
guerrei has been reported to kill the host
queen in laboratory studies (temporary
social parasitism; Bruch 1930), but has
been found to allow the host queen to
live in field studies (permanent social
parasitism; Silveira-Guido et al. 1965).
It may be that under certain conditions S.
daguerrei exhibit either form of social
parasitism. This species is known to be
a social parasite of Solenopsis invicta, S.
richteri, S. macdonaghi, and S. quin-
quecuspis (Santschi 1930, Briano et al.
1997, Calcaterra et al. 2000). Borgmeier
(1959) reported S. hostilis as a parasite
of S. saevissima (Smith), but did not
gather any natural history information
for the species. Solenopsis solenopsidis is
reported to be a permanent social parasite
of S. clytemnestra Emery (Kusnezov
1954). Ho¨lldobler and Wilson (1990) re-
viewed social parasitism and included the
known parasites and hosts of the Sol-
enopsis social parasites. However, the
host records they listed often disagreed
with those of the primary publications
(Bruch 1930; Santschi 1930; Borgmeier
1949, 1959; Kusnezov 1954, 1957; Silveira-
Guido et al. 1965). Solenopsis enigmatica
is known from only a single collection
from Pheidole dentata Mayr and is hy-
pothesized to be a temporary social par-
asite (Deyrup and Prusak 2008).
MATERIALS AND METHODS
Loaning institutions and depositories
of specimens.—Specimens used in this
study were either borrowed from col-
lections at the following institutions or
have been deposited in them:
AEIC – American Entomological Institute,
Logan, Utah, USA.
AMNH – American Museum of Natural
History, New York, USA.
VOLUME 120, NUMBER 2 313
BMNH – The Natural History Museum,
London, United Kingdom.
CNCI – Canadian National Collections,
Ottawa, Canada.
DZUP – Colec¸a˜o Entomolo´gica Padre Jesus
Santiago Moure, Curitiba, PR, Brazil.
EMUS – Entomological Museum, De-
partment of Biology, Utah State University,
Logan, Utah, USA.
FSCA – Florida State Collection of Arthro-
pods, Gainesville, Florida, USA.
ICIB – Museu de Entomologia, Instituto de
Biologia, FEIS/UNESP, Ilha Solteira, Sa˜o
Paulo, Brazil.
IMLA – Fundacion e Instituto Miguel Lillo,
Tucuma´n, Argentina.
JPPC – J. P. Pitts Personal Collection,
Millville, Utah, USA.
LACM – Los Angeles County Museum of
Natural History, Los Angeles, California,
USA.
MACN – Museo Argentino de Ciencias Nat-
urales, Buenos Aires, Argentina.
MCZ – Museum of Comparative Zoology,
Cambridge, Massachusetts, USA.
MHNG – Muse´um d’Histoire Naturelle,
Geneva, Switzerland.
MZSP – Museu de Zoologia, Universidade de
Sa˜o Paulo, Sa˜o Paulo, Brazil.
NHMB – Naturhistorisches Museum, Basel,
Switzerland.
SDPC – Sanford D. Porter Personal Collec-
tion, Gainesville, Florida, USA.
UCDC – University of California, Davis,
California, USA.
UGCA – University of Georgia Collection of
Arthropods, Athens, Georgia, USA.
USNM – National Museum of Natural His-
tory, Washington, D.C., USA.
Sample collection.—Due to the taxo-
nomic difficulties with the S. saevissima
species-group, it was deemed important to
obtain specimens from localities through-
out each species’ known range in order
to infer the extent of geographically-
based variation in character states within
species. Furthermore, it was necessary
to have all relevant castes and life stages
available for study of novel character
systems, and these specimens needed to
be associated with adult workers from
the same colony. Unfortunately, such
material is not readily available from
museums. Therefore, extensive sam-
pling was conducted in South America
during trips made by KGR and others in
1988, 1992, and 1998, by KGR and JPP
in 2001, and by DG and GPC in 2015.
These efforts produced new specimens
from more than 1,500 colonies.
Other new material that was utilized
for this study includes 118 colonies
sampled in South America in 1991 by
Sanford D. Porter (SDPC). This material
provided adult workers and some alate
(winged) gynes for study. The alcohol
collection at the FSCA held samples of
undetermined South American Solenopsis
from more than 1,500 colonies that were
collected primarily by William F. Buren.
Material from the 1988 and 1992 col-
lecting trips made by KGR was identified
by James C. Trager and from the 2015
collecting trip was identified by DG and
GPC. All other material in the study was
identified by JPP.
Material examined.—Although the
main focus of this study is the S. sae-
vissima species-group, specimens of many
other Solenopsis species were studied in
order to give insight into the usual levels of
interspecific variation within the genus and
to indicate other possible characters of
taxonomic importance in the S. saevissima
species-group. Listed alphabetically below
are all species examined for this study.
Four forms of each species (adult males,
adult gynes [winged or dealated members
of the queen caste], adult workers, and
larval workers) were studied unless other-
wise indicated: S. abdita Thompson, S.
amblychila Wheeler (adults, all castes),
S. aureaWheeler (adults, all castes), S. bruesi
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON314
Creighton (adult workers), S. carolinensis
(Forel) (adult gynes andworkers), S. castor
Forel (adult workers), S. clytemnestra
Emery (adult workers), S. corticalis Forel
(adult gynes and workers), S. daguerrei
Santschi (adult males and gynes), S. elec-
tra Forel (adult gynes and workers), S. fu-
gax (Lat.) (adults, all castes), S. gayi
(Spinola) (adults, all castes), S. geminata
(Fabricius), S. globularia littoralis (Smith),
S. interrupta Santschi, S. invicta Buren, S.
krockowi Wheeler, S. macdonaghi Sant-
schi, S. megergates Trager, S. molesta
(Say), S. nigella Emery, S. pergandei Forel
(adults, all castes), S. picta Emery, S. pu-
sillignis Trager, S. pythia Santschi (adult
gynes and workers), S. quinquecuspis
Forel, S. richteri Forel, S. saevissima
(Smith), S. substituta Santschi, S. succinea
Emery (adult gynes and workers),
S. tennesseensis Smith (adult males and
workers), S. tenuis Mayr (adult
workers), S. texana Emery (adult and
larval workers), S. tonsa Thompson
(adult workers), S. tridens Forel, S. virulens
(adult workers), S. westwoodi Forel
(adults, all castes), S. weyrauchi Trager
(adult workers), and S. xyloni McCook.
Specimen preparation.—For scanning
electron micrographs, the adults and
larvae were dehydrated in ethanol and
critical point-dried before being sput-
ter-coated with gold. Several attempts
were made to prepare specimens using
hexamethyldisilazane (HMDS), as de-
scribed by Nation (1983), but because
this approach often caused damage to
adult male and larval specimens it was
discontinued.
For stereoscopic light microscopy,
workers were air-dried after storage in
70%-85% ethanol. Air-drying speci-
mens, especially males, directly from an
alcohol solution often causes the head
and mesosoma to collapse, resulting in
low quality specimens. Therefore, males
and gynes were saturated with amyl
acetate and allowed to slowly air-dry in
a fume hood. This technique prevented
fragile specimens from collapsing and
also helped to maintain their natural color.
Morphological terminology and
measurements for adults.—Several fea-
tures of the head were used in this study.
The positions of the compound eyes (ce)
and ocelli (oc) are important and are
labeled in Figs. 1, 4, 9, and 10. The
apices of the clypeal carinae (cc) (Fig. 1)
are called clypeal teeth. Sometimes
paracarinal teeth are present lateral to
clypeal teeth, as is a small median tooth
(mct) between the clypeal teeth (Fig. 1).
Often a linear or triangular shaped, darkly
pigmented area, called a median frontal
streak (fs = frontal median streak), is present
on the head (Fig. 50).
The mesosoma of the worker is di-
vided into several well-defined regions.
Visible in dorsal view are the pronotum
(prn), mesonotum (mes), metanotum
(met), and the propodeum (ppm) (Fig. 2).
In lateral view, the profiles of these, as
well as the mesopleura (msp), are visible
(Fig. 3). The mesosoma of males and
gynes is divided into additional sclerites.
The following are usually visible: pro-
notum (prn), mesonotum (mes), para-
psidal lines (pl), scutellum (sct), axillae
(ax), metanotum (met) and propodeum
(ppm) (Figs. 2, 5, 9). The mesopleuron is
divided into a dorsal sclerite, the anepis-
ternum (an), and a ventral sclerite, the
katepisternum (k) (Figs. 5, 9). The wing
venation terminology used here (see Fig. 11)
is based on the system proposed by
Comstock (1918), Ross (1936), and
Mason (1986).
The metasoma has a two-segmented
petiole. These two segments are referred
to as the petiole (pt) and the post-
petiole (ppt) (Figs. 5, 9). The dorsal
surface of each of the segments is modi-
fied as an upwardly directed scale or as
a rounded node when viewed laterally.
VOLUME 120, NUMBER 2 315
The remaining portion of the metasoma,
the gaster, is comprised of four segments,
each bearing a dorsal plate (tergite) and
ventral plate (sternite). The tergites and
sternites covering these segments are
numbered from anterior to posterior as
T1, T2, T3, T4, and S1, S2, S3, and S4,
respectively.
The male genitalia are composed of
several structures. The outermost struc-
tures are the parameres. Mesad of the
parameres are the volsellae (Fig. 74).
Each volsella has a single cuspis (cus)
and digitus (dig) (Fig. 74). The in-
nermost organ is the aedeagus, which
has an apodeme (ap) projecting dorsally
(Fig. 74) (Snodgrass 1941).
Measurements of adult Solenopsis
were made at 50X or 100X on a stereo
dissecting microscope with either an
ocular micrometer or a digital microm-
eter. All measurements are reported in
millimeters. Measurements of holotypes
are listed separately in parentheses.
Head measurements were made with the
head held in dorsal view, positioned so
that the greatest straight-line distance
between the midpoints of the clypeal
border and the vertex was achieved. The
viewing axis was approximately per-
pendicular to the surface of the frons.
Abbreviations and definitions for mea-
surements and indices are given below:
L Total length of the ant, measured in
lateral view with the head in a natural
hypognathous position. This mea-
surement is not as accurate as the
DML measurement (below) due to
distortion of the metasoma that is
caused by alcohol preservation and
subsequent drying of specimens.
HW Maximum width of the head, in-
cluding the eyes, measured in full-
face, dorsal view (Fig. 6).
VW Width of the posterior portion of the
head (vertex), measured along a line
drawn through the lateral ocelli, with
the head in full-face, dorsal view
(Fig. 6).
HL Midline length of head, measured in
full-face, dorsal view, from the an-
terior clypeal margin to the midpoint
of a line drawn across the occipital
margin (Fig. 6).
EL Maximum length of compound eye,
measured with the head in full-face,
dorsal view (Fig. 6).
OD Ocellar distance, measured as the
distance from the middle of the me-
dian ocellus to the midpoint of a line
drawn between the lateral ocelli.
Measured with the head in full-face,
dorsal view (Fig. 6).
OOD Ocellocular distance, measured as
the distance from the middle of the
median ocellus to a line drawn across
the posterior margins of the com-
pound eyes (this distance is negative
in value if the posterior margin of the
compound eye exceeds the median
ocellus) (Fig. 6).
LOW Maximum width of the lateral ocelli.
MOW Maximum width of the median
ocellus (Fig. 6).
CD Distance from the anterior clypeal
margin to a line drawn across the
anterior margins of the frontal cari-
nae (Fig. 6).
MFC Minimum distance between the
frontal carinae, measured with the
head in full-face, dorsal view.
EW Maximum width of compound eye,
measured along its short axis, in an
oblique dorsolateral view of the head.
SL Length of scape, excluding the radicle
(Fig. 6).
SW Maximum width of the scape, mea-
sured only for males.
PDL Maximum exposed length of the
pedicel, excluding the concealed
basal articulating area.
PEW Maximum width of the pedicel,
measured only for males.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON316
LFl Maximum exposed length of the
first flagellomere.
LF2 Maximum exposed length of the
second flagellomere.
LF3 Maximum exposed length of the
third flagellomere.
WF1 Maximum width of the first
flagellomere.
FL Maximum exposed length of the fore
femur, measured in posterior view.
FW Maximum measurable width of the
fore femur, measured from the
same view as FL, at right angles to
the line of measurement of FL.
PW Maximum width of the pronotum
in dorsal view, measured only for
the major workers.
MW Width of the mesonotum in dorsal
view, anterior to tegulae.
DML Diagonal length of the mesosoma,
measured in lateral view along a di-
agonal line drawn from the ante-
rior base of pronotum (exclusive of
anterior "cervical flange" which is
often concealed) to posterior edge
of metapleuron (Fig. 7).
PL Petiole length, measured in lateral
view from the lateral flanges of the
anterior peduncle to the posterior
margin of the petiole (Fig. 8).
PND Petiolar node distance, distance
from the anterior margin of petiole
to a vertical line drawn through the
petiole at the highest point of the
node, measured from the same
view as PL (Fig. 8).
PH Maximum height of the petiole,
measured in lateral view at right an-
gles to PL, but excluding the ante-
roventral process (Fig. 8).
PPL Length of the postpetiole, measured
in lateral view, from the anterior
peduncle of the postpetiole to the
point of contact with the fourth ab-
dominal tergite.
DPW Maximum width of the petiole,
measured in dorsal view.
PPW Maximum width of the postpetiole,
measured in dorsal view.
PHB Height of postpetiole, as measured
from attachment of postpetiole to T1.
Indices calculated from the preceding mea-
surements include the following ratios:
CI Cephalic index: HW/HL
OI Ocular index: EW/EL
REL Relative eye length: EL/HL
REL2 Relative eye length, using HW: EL/
HW
OOI Ocellocular index: OOD/OD
VI Vertex width index: VW/HW
FCI Frontal carinal index: MFC/HW
CDI Clypeal distance index: CD/HL
SI Scape index: SL/HW
SI2 Scape index, using EL: SL/EL
SI3 Scape index, using LF2: SL/LF2
FI Fore femur index: FW/ FL
NI Petiole node index: PND/PL
PLI Petiole length index: PH/PL
PHI Petiole height index, using PPL: PH/
PPL
PWI Petiole width index: DPW/PL
PPWI Postpetiole width index: PPW/PPL
PPWB Postpetiole width index, using
PHB: PPW/PHB
The measurements for workers reported
here differ from those of Trager (1991) as
follows: the abbreviation DML is used in-
stead of AL to denote diagonal length of
the mesosoma, REL is used instead of OI
for relative eye length, and CI, SI, and REL
are not converted to percentages. Mea-
surements of head length reported here
include the length of the clypeal teeth.
Morphological terminology and
measurements for larvae—Only fourth
instar worker larvae or prepupae were used
for the study. The fourth instar is discern-
ible by the completely sclerotized mandi-
bles (Petralia and Vinson 1979). Larvae
were prepared as outlined in Wheeler
(1960). The morphological terminology
VOLUME 120, NUMBER 2 317
follows that of Wheeler and Wheeler
(1976) (Fig. 12), however, several rows of
setae also were named as follows: occipital
setal row (= posterior row of setae on head)
(Fig. 13), first setal row of the vertex
(Fig. 14), and second setal row of the
vertex (Fig. 15). Measurements were made
at 400X or 1000X on a compound micro-
scope. Length was measured using the spi-
racles as in Wheeler and Wheeler (1976).
Standard taxonomic descriptions are
provided for adult males, adult gynes
and larval workers in the S. saevissima
species-group. A standard dichotomous
key is provided that incorporates useful
characters from adult males and gynes.
A tabular key is also provided.
RESULTS
Solenopsis saevissima species-
group.—Diagnoses for the gynes, males,
and larvae of the non-parasitic species of
the S. saevissima species-group are
given below. Due to the drastic modifi-
cation in body form in the social para-
sites, descriptions of each species are not
provided here. Instead, the description
of S. daguerrei serves to distinguish
all socially parasitic species from the
remainder of the species-group. Sol-
enopsis hostilis has been included in the
key for completeness, although no
specimens were found during this study
and the species apparently has not been
collected since its original description.
To avoid repeating the descriptive
treatment of the workers by Trager
(1991), only diagnostic combinations
of characters for the major workers are
given here.
Gyne.—Head: Usually broader than
long, quadrate, wider posterior to eyes
than anterior to them, sides weakly
convex from eyes to occipital angles,
straight to slightly convex ventral to
eyes and meeting anterior border of
head at a sharp angle (Fig. 1). Occipital
angles distinctly defined, occiput flat
with narrow, shallow median impres-
sion. Occipital furrow clearly to weakly
defined. Frontal furrow indistinct.
Clypeus projecting, carinal teeth very
stout and acute, clypeus with anterior
shallow concave impression between
carinal teeth (Fig. 1). Paracarinal teeth
small (Fig. 20), often poorly defined and,
in some cases, absent (Fig. 1). Median
carinal tooth well developed (Fig. 1) to
indistinct (Fig. 20). Mandibles with
outer border convex, masticatory border
with four teeth, fourth tooth much
smaller than others (Fig. 1). Eyes large,
strongly convex, ovate (Figs. 1, 4). An-
tennal scape in repose reaches or passes
lateral ocellus. Antenna with 11 seg-
ments (10 segments sometimes in S.
pythia) with 2-segmented club.
Mesosoma: Robust, elliptical, only
slightly narrower than head (Fig. 2). In
lateral view, mesonotum with convex
anterior portion that overhangs pronotum
and with straight posterior half (Fig. 5).
Scutellum as high or higher than mes-
onotum, slightly convex with short per-
pendicular posterior face, posterior
face depressed posteromedially (Fig. 5).
Angle of propodeum well defined but
obtuse, basal face shorter than declivous
face (Fig. 5). Mesosternum large and
subglobose ventrally (Fig. 5). Wings hy-
aline with yellow to brown veins (veins
hyaline in S. daguerrei and sometimes in
S. electra).
Metasoma: In lateral view, petiolar
node obtusely triangulate, profile of pe-
duncle flattened anteriorly, convex pos-
teriorly (Fig. 5). Petiole with median
longitudinal carina on anterior 0.50–0.75
of ventral surface (Fig. 5). Postpetiole
evenly convex (Fig. 5). Lateral faces of
postpetiole concave to slightly convex.
Petiolar and postpetiolar spiracles are
tuberculate in some cases. Petiole with
basal transverse carina, appears tooth-like
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON318
in lateral view. In dorsal view, nodes are
very strongly transverse, and post-
petiole wider than petiole. In cephalic
view, petiole sometimes with distinct
median lobe, postpetiole broader than
high, highest medially.
Male.—Head: Trapezoidal, maxi-
mum head width greater than length
(Fig. 10). Eyes very large, strongly
convex, ovate, occupying more than
0.5X side of head, their anterior border
almost reaching insertion of mandible
(Fig. 10). Eyes normally with setae
protruding from between ommatidia.
Ocelli small to large and prominent, el-
liptical (Fig. 10), lateral ocelli marking
boundary of occiput with shallow con-
cave depression between them. Anterior
edge of clypeus approximately straight
(Fig. 10). Clypeus with blunt, central
lobe in lateral view (Fig. 9). Mandibles
small, straight, tridentate, third tooth
small, sometimes indistinct. Antennal
scape longer than broad, roughly cylin-
drical. Pedicel subglobose, broad or
broader than scape or flagellomeres (Fig.
10). First flagellomere >2.0X as long as
broad, second flagellomere <1.6X as
long as broad, remaining flagellomeres
progressively decreasing in width.
Mesosoma: Robust, elliptical, width
less than twice that of head. In lateral
view, anterior part of mesonotum greatly
swollen and overhanging pronotum (Fig.
9). Propodeum rounded, declivous face
perpendicular and flat except with dis-
tinct to indistinct median longitudinal
depression (Fig. 9), basal face strongly
convex transversely and longitudinally.
Mesosternum large and subglobose
ventrally (Fig. 9). Wings hyaline with
hyaline to yellow veins.
Metasoma: Node of petiole short in
lateral view with acute dorsum (Fig. 9);
anterior face not sharply separated from
thick peduncle, posterior face perpen-
dicular laterally, gently curving medially
(Fig. 9). In cephalic view, dorsum of
node with shallow median impression,
sometimes bilobate. Postpetiole in lat-
eral view as high as node of petiole,
anterior face, dorsum and posterior face
rounded (Fig. 9). In dorsal view, both
nodes very transverse, postpetiole is
approximately 1.0–3.0X as broad as long
and as wide as node of petiole. Petiolar
and postpetiolar spiracles distinctly tu-
berculate to not tuberculate. Genitalia
strongly retracted (Fig. 74). Cuspis lat-
erally flattened, lobate in lateral view
and lacking setae (Fig. 74). Digitus short
and cylindrical, with apical setae and
sometimes with lateral setae (Fig. 74).
Ventral portion of volsellar plate apically
produced, clothed with several setae
(Fig. 74). Ventral surface minutely den-
tate with rows of triangular teeth (Fig.
74). Ventral margin of aedeagus with
many anteriorly directed triangular teeth
(Fig. 74). Aedeagus with anteroventrally
directed triangular projection (Fig. 74).
Apodeme of aedeagus directed perpen-
dicular to slightly obtuse to ventral sur-
face (Fig. 74).
Sculpture and Pilosity: Punctures fine
and numerous, < 0.001mm wide. An-
tenna covered with dense, short, white
pubescence. Pubescence on legs shorter
and stouter than on body.
Fourth instar worker larva.—Head:
Antenna with 2–3 sensilla, each bearing
spinule (Fig. 12). Head setae sparse (Fig.
12). Cranial width equal to or slightly
broader than long (Fig. 12). Labrum
small, short, slightly narrowed medially
(Fig. 12). Mandible heavily sclerotized
with two parts (Fig. 12): 1) stoutly
sickle-shaped body, with three apical
teeth not in same plane; 2) straight me-
dial blade forming 0–5 teeth that de-
crease in size dorsally. Ventral border of
labrum weakly concave with ventral
corners rounded (Fig. 12). Labrum
bearing 2–3 coarse isolated spinules near
VOLUME 120, NUMBER 2 319
each ventrolateral corner. Maxilla with
sclerotized band between cardo and sti-
pes. Labium with patch of spinules dor-
sal to palpus. Labium with small lateral
sclerotized bands. Opening of sericteries
a long transverse slit (Fig. 12).
Body: Stout. Prothorax bent ventrally
at right angles forming very short stout
neck. Remainder of body straight. Ab-
dominal diameter greatest at fourth
somite. Both ends of body broadly
rounded. Dorsal profile of body curved,
ventral surface nearly flat. Anus ventral.
Leg and wing precursors present. Seg-
mentation indistinct. Integument of
ventral surface of thorax and first three
abdominal somites with few short
transverse rows of minute spinules.
Body setae numerous, short, and uni-
formly distributed. Body setae of two
types: 1) simple, slightly curved with
alveolus and articular membrane, 4–12
in transverse row on ventral surface of
each thoracic somite and anterior ab-
dominal somites; 2) bifid, branches more
or less perpendicular to base, tips re-
curved occurring on various regions of
body; often setae posterior to head on
thoracic dorsum differ slightly from
other setae. Setae on ventral surface with
alveolus and articular membrane.
Length: Approximately 2.3–3.8 mm.
Comments.—Indices calculated from
adult measurements are provided for
gynes and males in Tables 5 and 6,
respectively.
Identification of fire ants.—The
characters used here for the identifica-
tion of fire ants are those normally used
for myrmecological taxonomic work.
The most useful characters for the
workers are size, coloration, head shape,
and postpetiolar shape. After thorough
examination of males and gynes, we feel
that the workers are superior to sexuals
for distinguishing the various species.
The gynes and males of many species
are very similar and in some cases are
indistinguishable between species with-
out a reference collection. Some gyne
characters such as pilosity or sculpturing
are highly variable, as they are for
workers, but sometimes can be useful.
Size, coloration, and head shape are also
of some use in identification of the
gynes. Coloration and size of males tend
to be very similar for many species,
making these characters of limited value
for identification purposes. Some spe-
cies, however, have reliable male sculp-
ture characters.
Geographical distribution can be use-
ful for identifying fire ants but can be
biased by several factors. As mentioned
by Trager (1991), fire ants are easily
transported to new regions, which makes
geographical information valuable only
as a complement to other data. Also, the
available distributional data for most
species are patchy and are almost cer-
tainly incomplete; therefore, some spe-
cies could have much broader ranges
than are reported here. On the other
hand, occurrence records for fire ants are
often incorrect due to misidentifications
or habit of assigning specimens to the
most common species (e.g., S. invicta or
S. saevissima) and reported ranges can
hence be grossly overestimated. We there-
fore deliberately omitted use of other
sources (Antweb, Antmaps) in the con-
struction of maps to avoid aforemen-
tioned errors. Consequently, we present
maps as conservative range estimates
based mainly on our own collections
and, when feasible and sufficiently dif-
ferent from our collections, the type lo-
calities. For rarer species (e.g., S. pythia,
S. weyrauchi, or S. electra), we also in-
cluded reliable collection site records
from Trager (1991).
In this work, an effort was made to
follow the format of the descriptions
of prior Solenopsis authors to facilitate
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON320
future systematic work on the group. As
such, adult worker descriptions follow
the format of Trager (1991), adult male
and gyne descriptions follow the format
of Creighton (1930), and larval de-
scriptions follow the format of Wheeler
and Wheeler (e.g., Wheeler and Wheeler
1976, 1986).
KEY TO THE SOLENOPSIS SAEVISSIMA SPECIES-GROUP
(Modified from Trager 1991)
This key is not intended for the identification of minor workers. To fully utilize all of the
available information and to obtain an accurate identification, one should take a sizeable
sample of workers, males, gynes and larvae from a colony. Special effort should be made
to obtain major workers. A positive identification may be impossible for colonies lacking
such individuals, such as those sampled soon after founding. Tabular keys to the major
workers, gynes, andmales are presented in Tables 1, 2, and 3, respectively. These should be
consulted especially when a colony sample does not include representatives of all forms.
1. Gyne and male: small, 5.0 mm or less in length; sculpture reduced, body polished; meta-
pleuron fused to propodeum. Gyne: parapsidal lines absent; clypeus lacking longitudinal
carinae and apical teeth (Fig. 196); posterior margin of head broadly emarginated with
posterolateral corners angulate (see below and Fig. 195) (social parasites lacking workers)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Photo of casent0911238 by Alexandra Westrich. From www.antweb.org
[Accessed 20 July 2017].
– Gyne and male: larger, greater than 5.0 mm in length; sculpture not reduced, present at
least on propodeum, petiole and postpetiole; metapleuron not fused to propodeum. Gyne:
parapsidal lines present; clypeus with longitudinal carinae terminating in teeth apically
(Figs. 20, 22, 24, etc.); posterior margin of head narrowly emarginated medially with pos-
terolateral corners rounded (see below and Figs. 20, 22, 24, etc.) (free living with workers)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
VOLUME 120, NUMBER 2 321
Photo of casent0104504 by April Nobile. From www.antweb.org [Accessed 20 July 2017].
2(1). Gyne: posterior margin of head angulate (see below and Fig. 195), lobate in lateral view
(Fig. 196). Distribution: south from Mato Grosso do Sul, Brazil to Buenos Aires Province,
Argentina (Fig. 203) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. daguerrei
– Gyne: posterior margin of head rounded, not lobate in lateral view. Distribution: Jacarepagua´,
Rio de Janeiro, Brazil southwest to Rolaˆndia, Parana´, Brazil . . . . . . . . . . . . . . . S. hostilis
3(1). Major worker: pronotum low and nearly flat or weakly convex in profile (see below);
metasoma black, legs yellow (yellowish brown in darker specimens), head and mesosoma
ranging from clear yellowish red with some black or brownish black markings in the
occipital area to uniformly brownish black (especially in vicinity of Cochabamba, Bolivia).
Distribution: northwestern Argentina to Bolivia in Andean foothills (Fig. 201) . . . . S. electra
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON322
Drawing by James Trager. From Trager 1991 J. New York Entomol. Soc. (Fig. 42).
– Major worker: pronotum higher, angular or strongly convex in profile (see below); color
variable but never with metasoma completely black and with yellow legs . . . . . . . . . 4
4(3). Major worker: area immediately posterior and dorsal to metapleural spiracle finely punctate
or striato–punctate (see below and Fig. 140); largest major workers with head strongly
cordate (see below and Fig. 141). Male: weak to distinct mesonotal maculations present;
ocelli moderate to large, OOI 0.80–1.26, normally OOI<1.00 (Fig. 65). Distribution:
southern half of Mato Grosso, western Mato Grosso du Sul, Brazil (Fig. 203) . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. pusillignis
– Major worker: area surrounding metapleural spiracle shiny and smooth (see below and
Figs. 130, 132, 134, 136, 138, 142, 144, 146); largest major workers with head moderately
VOLUME 120, NUMBER 2 323
(see below and Figs. 131, 133, 137, 139) to weakly cordate (Figs. 135, 143, 145, 147). Male:
mesonotal maculations absent; male ocelli moderate to small, OOI > 1.00 (Figs. 57, 59, 61,
63, 67, 69, 71) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5(4). Major worker: posterior face of postpetiole as high or higher than broad (see below) . . . . . 6
– Major worker: posterior face of postpetiole broader than high (see below) . . . . . . . . 11
6(5). Major worker: pronotal dorsum in posterodorsal view medially concave; anterolateral bosses
giving squared-off appearance to anterodorsal rim of pronotum (see below); head uniformly
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON324
brownish black; mandibles usually brownish yellow; frons without dark median streak or
this barely distinct from remainder of frons. Male: often with distinct tuberculate postpetiole,
tubercle height ³ 1.5X width at base, tubercles glabrous; OOI < 1.35. Distribution: south-
eastern Brazil to central eastern Argentina (Fig. 203); introduced into southeastern United
States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. richteri
Photo of casent0103101 by April Nobile. From www.antweb.org [Accessed 20 July 2017].
– Major worker: pronotal dorsum in posterodorsal view usually flat or weakly convex; pro-
notum lacking anterolateral bosses (see below); or if bosses present, head yellowish, at least
near mandibular bases and clypeus and often more extensively yellowish; Male: often
lacking distinct tuberculate postpetiole, tubercle height £ 1.5X width at base, tubercles
granulate or rugose; OOI > 1.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Photo of casent0005804 by www.antweb.org [Accessed 20 July 2017].
7(6). Major worker: median streak (frontal streak, fs) usually present (see below and
Fig. 50). Gyne: mesonotal maculations present (Fig. 52) (gyne of S. weyrauchi was not
examined) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
VOLUME 120, NUMBER 2 325
– Major worker: median frontal streak usually absent (see below). Gyne: mesonotal macula-
tions usually absent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8(7). Major worker: large with DML exceeding 1.75 mm (sometimes over 2.0 mm) in largest
workers of most series; piligerous foveolae small (<0.01 mm, see below). Gyne: if T1
maculation present, it sometimes has distinctly defined posterior margin. Distribution: nor-
mally lowlands species in western Argentina and Bolivia (Fig. 202) . . . . . . S. interrupta
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON326
– Major worker: small with DML rarely in excess of 1.7 mm in even largest workers of most
series (rarely up to 1.80 mm); piligerous foveolae large (0.005–0.03 mm, see below); Gyne:
if T1 maculation present, it lacks a distinctly defined posterior margin (gyne of S. weyrauchi
was not examined). Distribution: normally high elevation species . . . . . . . . . . . . . . . 9
9(8). Major worker: cephalic piligerous foveolae small (<0.01 mm); rear face of postpetiole with
striae present on lower 0.50–0.75 (see below); mandibles with 5–6 costulae; katepisternum
of mesopleuron not or only weakly defined dorsally by finely striate furrow. Gyne un-
known. Distribution: Peruvian, Bolivian, and Argentinian Andes, 2,000–3,500 m elevation
(Fig. 201) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. weyrauchi
VOLUME 120, NUMBER 2 327
Drawing by James Trager. From Trager 1991. J. New York Entomol. Soc. (Fig. 81).
– Major worker: cephalic piligerous foveolae large (0.01–0.03 mm); scape long, almost
reaching the vertex of the head; rear face of postpetiole with striae present on lower 0.25–
0.33 and smooth and shiny upper (see below and Fig. 19); mandibles with 10–12 costulae,
weak to obsolescent medially; katepisternum of mesopleuron weakly to distinctly defined
dorsally by finely striate furrow (Fig. 18); promesonotal suture angulate medially, sometimes
projecting upward (Fig. 18); first sternite of gaster with anterior projections, visible in dorsal
view. Gyne: large piligerous foveolae (0.01–0.03 mm) present on head; interfoveolar areas of
head striate; ocellar triangle striate (Fig. 20); median cell open by loss of m-cu cross vein
(Fig. 89); postpetiole glabrous on upper 0.75 (Fig. 44). Distribution: southern and south-
eastern Brazil, northeastern Argentina (Fig. 201) . . . . . . . . . . . . . . . . S. metallica n. sp.
10(7). Major worker: larger, DML 1.4–l .6 mm (rarely 1.7 mm) in large workers; piligerous fo-
veolae usually very small, inconspicuous. Gyne: cephalic pilosity approximately 0.30–0.33
mm long; metasoma pilosity arising from small, inconspicuous foveolae; median furrow on
posterior 0.33 or less of mesonotum; bidentate metasternal process present. Larger species.
Distribution: Orinoco drainage, Guianas, Amazonia and along rivers in bordering regions,
also southeastern and eastern Brazil (Fig. 201) . . . . . . . . . . . . . . . . . . . . S. saevissima
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON328
– Major worker: smaller, DML < 1.4 mm in even the largest workers; piligerous foveolae on
head and pronotum sometimes conspicuous, 5–l0X as wide as base of seta. Gyne: cephalic
pilosity about 0.15–0.20 mm long (Fig. 53); metasoma pilosity arising from conspicuous
piligerous foveolae nearly or actually as large as those of head and mesosoma (Fig. 51);
median furrow on posterior 0.33–0.50 of mesonotum (Fig. 51); bidentate metasternal pro-
cess absent. Smaller and much rarer species. Distribution: Mato Grosso do Sul to south-
eastern Brazil and Misiones, Argentina (Fig. 202) . . . . . . . . . . . . . . . . . . . . . . S. pythia
11(5). Major worker: smaller, DML rarely in excess of 1.70 mm in even largest workers of most
series; median (frontal) streak (fs) present (see below). Gyne: frontal streak present (as in Fig. 50),
sometimes faint; postpetiole usually completely sculptured, only extreme dorsum lacking
striae (Fig. 42). Male: head usually completely granulate, shagreened; gena moderately to
coarsely rugose. Distribution: lowland species, western Amazonia, south through Mato
Grosso, eastern Bolivia, Paraguay and southeastern Brazil to Santa Fe Province, Argentina
(Fig. 203); introduced into Southern United States . . . . . . . . . . . . . . . . . . . . . . S. invicta
– Major worker: larger, DML exceeding 1.75 mm (up to over 2.0 mm) in largest workers of
most series; median frontal streak usually absent (see below). Gyne: median frontal streak
usually absent; postpetiole usually completely sculptured, only highest portion lacking striae
(Figs. 41, 43). Male: head usually incompletely granulate, glabrous anterolaterally of median
ocellus, not shagreened; gena striate to granulate . . . . . . . . . . . . . . . . . . . . . . . . . . 12
VOLUME 120, NUMBER 2 329
12(11). Major worker: color mainly red to orange; mesosoma pilosity usually decumbent, not curved;
transverse striae or rugae on rear face of postpetiole usually lacking, or faint, punctate or
shagreened (see below); outer surface of mandible usually shining medially, costulae obso-
lescent. Distribution: Uruguay, Entre Rios Province and adjacent parts of bordering provinces
in Argentina; apparently introduced at Cochabamba, Bolivia (Fig. 202) . . . S. macdonaghi
Drawing by JamesTrager. From Trager 1991 from J. New York Entomol. Soc. (Fig. 63).
– Major worker: color brown to nearly black; mesosoma pilosity erect, longest setae usually
curved; sculpture on rear face of postpetiole with conspicuous transverse striae or rugae on
lower 0.66–0.75, punctate or shagreened (see below); outer surface of mandible with
costulae, sometimes obsolescent medially . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON330
DESCRIPTIONS
Solenopsis metallica Pitts, Camacho,
Gotzek, McHugh, and Ross,
new species
urn:lsid:zoobank.org:act:D0AC4A84-
95B8-4E9D-9FA9-FBB76636ABDA
(Figs. 16–20, 44, 89)
Solenopsis altipunctata Pitts, 2002: 63.
Nomen nudum.
Solenopsis species ‘A’: Krieger and Ross
2005; Shoemaker et al. 2006.
Solenopsis altipunctata Gotzek et al.
2007. Nomen nudum.
Solenopsis saevissima ‘southern high-
lands’: Ross et al. 2010.
Holotype.—Brazil: Santa Catarina
State, Rt.166 ca 22 km north of Santa
Cecilia, Serra Geral, 1200 m, .xi.1998,
K. G. Ross, M. C. Mescher, D. D.
Shoemaker, and L. Keller, n. G-84
[USNM: 1worker, USNMENT01126728].
Paratypes.—Brazil: Santa Catarina
State, Rt.166 ca 22 km north of Santa
Cecilia, Serra Geral, 1200 m, .xi.1998,
K. G. Ross, M. C. Mescher, D. D.
Shoemaker, and L. Keller [MZSP: 1 worker,
G-83, USNMENT01126729], [DZUP: 1
worker, G-84, USNMENT01126730],
[EMUS: 1 worker, G-84, USNMENT-
01126731], [UGCA: 1 worker, G-83,
USNMENT01126732]. Brazil: Parana´
State, Edge of Ponto Grossa, median of
Rt.PR-513, 20.xi.2015, G. Camacho and
13(12). Major worker: small with HL 1.45–l .55 mm; eye of largest workers relatively (and
often absolutely) larger, REL 0.18–0.20 in large majors; head mostly dark brown to
brownish black; in contrast, distal portion of clypeus, head near base of mandible, and
(usually) area around dark median frontal sulcus distinctly lighter yellowish
brown. Male: lateral faces of scutellum weakly to distinctly striate. Distribution:
Buenos Aires and La Pampa Provinces, Argentina, Uruguay, north to Santa Catarina,
Brazil (Fig. 202) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. quinquecuspis
– Major worker: large with HL 1.6–1.75 mm in largest workers; eye of largest workers
relatively (and often absolutely) smaller than above species, REL 0.16–0.18 in large
majors; head uniform reddish brown or gradually fading anteriorly to a slightly lighter
reddish brown; distal portion of clypeus, sides of head anterior to eye, and frons faintly or
not at all chromatically distinct from posterior portions of head, median frontal streak
absent or very faint. Male: lateral faces of scutellum glabrous. Distribution: Southern
Brazil (Fig. 202) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. megergates
VOLUME 120, NUMBER 2 331
D. Gotzek, n. PR15-084 [USNM:
1 male, USNMENT01126733; 1 gyne,
USNMENT01126734].
Diagnosis of major worker.—Head
broad, cordate (Fig. 16). Head sculpture
with large piligerous foveolae, 0.01–0.03
mm in diameter. Median frontal streak
present. Median ocellus absent (Fig. 16).
Scape long, almost reaching the vertex of
the head. Mandibular costulae well de-
veloped throughout entire length. Meso-
notum with 30–36 setae. Promesonotal
suture in largest major workers angulate
medially, sometimes projecting upward
(Fig. 18). Propodeum sculpture glabrous
posteroventral to spiracle (Fig. 18). Post-
petiole shape as high as or higher than
broad (Fig. 19). Postpetiole sculpture in
posterior view with lower 0.25–0.33
transversely rugose, upper surface glabrous
and shiny (Fig. 19); first gaster sternitewith
anterior projections, visible in dorsal view.
Major worker.—Head: Cordate, slightly
longer than broad, widest posterior to eyes,
sides weakly convex (Fig. 16). Posterior
border of head with concave median im-
pression, concavity 0.5X as wide as dis-
tance between apices of frontal lobes.
Lower edge of anterior border of clypeus
bearing large median seta borne on weakly
developed median tooth, tooth is absent in
some specimens (Fig. 16). Clypeal cari-
nae, strongly developed, divergent distally,
projecting as triangular teeth that are no-
tably larger than median tooth and much
larger than paracarinal teeth (Fig. 16).
Paracarinal teeth reduced in some speci-
mens. Carinal and paracarinal teeth more
dorsally on clypeal border than median
tooth (Fig. 16). Mandible with normal
curvature (Fig. 16), four teeth (Fig. 16),
and 10–12 fine costulae, weakly de-
veloped or obsolescent medially, apically
becoming broader with shallower inter-
costular furrows on upper surface. Eye
ovate, with maximum diameter 10–12
ommatidia, and minimum diameter 6–7
ommatidia. Scape curved basally, thickest
subapically. Apex of scape in repose not
surpassing posterior border of head.
Mesosoma: Anterodorsal pronotal bor-
der, weakly convex (Fig. 18). Anterolateral
pronotal corners variously rounded,
never distinctly angulate and bearing
slight humeral bosses. Promesonotal
suture angulate medially with small
dorsal projection at apex (Fig. 18). Pro-
notum with steep anterior declivity dis-
tinguished from dorsum with slight break
in outline at point of anterior mesonotal
projection. Metanotal impression con-
spicuous, set off by steep, coarsely striate,
posterior mesonotal and anterior propo-
deal declivities (Fig. 18). Propodeum
with dorsal face slightly convex, curving
evenly into declivous face. Propodeum
angulate posterolaterally due to slight
longitudinal, posterolateral bosses. Mes-
opleural katepisternum defined dorsally
by finely striate impression (Fig. 18),
weakly defined in some specimens.
Metasoma: Petiolar peduncle notably
to slightly shorter than base of node.
Postpetiolar node globular to sub-
rectangular with dorsum convex, lateral
faces straight, parallel to convergent
ventrally. Postpetiole, as seen from be-
hind, with height greater than width.
Pilosity: Composed of yellow setae.
Longer setae curved. Mesonotum usually
with 30–36 erect setae. Mesopleuron with
several dorsal setae. Longest setae on
metasomal dorsum usually at least 3–4X
length of shortest. Suberect pubescence
present on cervical flange of pronotum,
on anterior face of petiolar nodes, and on
propodeal dorsum.
Sculpturing: Integument with distinct
piligerous foveolae present on head, meso-
soma and petiole, 0.01–0.03mm in diameter
(conspicuous even in minors). Piligerous
foveolae conspicuous but smaller on legs.
Interstitial area smooth, shiny. Sculpture
of metapleuron consisting of longitudinal
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON332
striae. Posterior face of petiole with striae
on basal 0.25. Posterior face of postpetiole
with transverse striae on basal 0.25, upper
0.75 glabrous with several conspicuous
piligerous foveolae (Fig. 19).
Coloration: Color varies from yellow-
orangewith brownmetasoma and with T1-
T4 lighter anteriorly to brown-red dorsally
with ventral portion of head and legs or-
ange, and T1 with apical margin orange.
Some specimens with darker medial por-
tions of leg segments. Median streak
present, but faint in some specimens.
Morphometric Measurements: HL
1.14–1.31, HW 1.00–1.24, SL 0.91–
1.06, EL 0.17–0.20, PW 0.59–0.70,
DML 1.48–1.70, CI 0.90–0.95, SI 0.80–
0.86, REL 0.14–0.16, N=21, (HL 1.21,
HW 1.14, SL 0.94, EL 0.18, PW 0.62,
DML 1.61, CI 0.94, SI 0.83, REL 0.15).
Gyne.—Head: Broader than long,
quadrate, wider dorsal to eyes thanventrally,
sides of head convex from eyes to occipital
angles, curving inwards to mandibular base
(Fig. 20). Eye sometimes with 1–4 setae
protruding from between ommatidia,
setae £ 3X length of ommatidium. Ocelli
small (Fig. 20). Median ocellus circular to
slightly elliptical; lateral ocelli ovate, smaller
than median ocellus (Fig. 20). Clypeus
projecting, carinal teeth stout and sharp,
carinaewell defined, less so dorsally, greatly
divergent ventrally (Fig. 20). Paracarinal
teeth small, sometimes poorly defined.
Median clypeal tooth poorly developed to
absent (Fig. 20). Approximately 0.33% of
eye dorsal to midpoint of head (Fig. 20).
Mesosoma. Narrower than head, ro-
bust, ovate. Parapsidal lines present on
posterior 0.50 to 0.75 of disk. Meso-
notum without posteromedian furrow.
Median bidentate process present on
metasternum. Wing venation as in Fig. 89,
m-cu cross vein absent, medial cell open.
Metasoma. Lateral faces of postpetiole
strongly to slightly concave. Petiolar spi-
racle tuberculate in some cases.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae large, width 0.01–
0.03 mm in diameter, larger on head than
on thorax and abdomen. Pubescence
simple, yellow and erect, longer and
denser on head than elsewhere, longest
on anterior edge of clypeus. Mesosoma
with longest pubescence (length >0.30
mm) 2X longer than shortest pubes-
cence. Mandible with 7–8 coarse, dis-
tinct costulae present throughout entire
length. Propodeum with fine striae pos-
teriorly, anterior 0.25% polished. Petio-
lar node with 0.25 coarsely striate,
remainder polished. Lower 0.25 of pos-
terior face of postpetiole granulate to
striato-granulate, upper 0.75% of surface
polished (Fig. 44). Area between ocelli
coarsely striate, sometimes drastically
so. Interfoveolar spaces on head finely
striate. Remaining integument smooth
and polished. Color orange with black
mesonotal maculations present ante-
romedially and around parapsidal lines.
Dorsal transverse band dark brown on
pronotum and mesopleuron. Metasoma
dark brown, except petiole ventrally and
basal 0.25% of T1 and S1 orange blend-
ing to dark brown apically. Leg segments
orange, brown medially. Sometimes T1
base completely dark brown. Internal
margins of ocelli dark brown.
Morphometric Measurements. L
;6.1–6.4, HW 1.30–1.40, VW 0.80–0.85,
HL 1.10–1.15, EL 0.31–0.36, OD 0.19–
0.22, OOD 0.16, LOW 0.04–0.06, MOW
0.07–0.09, CD 0.19–0.22, MFC 0.13–
0.15, EW 0.29–0.36, SL 0.90–1.01, PDL
0.14–0.16, LF1 0.08–0.11, LF2 0.07–0.10,
LF3 0.07–0.10, WF1 0.05–0.08, FL 1.10–
1.20, FW 0.19–0.30, MW 1.15–1.31,
DLM 2.34–2.51, PRH 0.93–1.10, PL
0.60–0.70, PND 0.55–0.65, PH 0.55–0.65,
PPL 0.25–0.35, DPW 0.50–0.65, PPW
0.66–0.74, PHB 0.34–0.44, N=2.
Male.—Head. Trapezoidal. Eye very
large, strongly convex, ovate, occupying
VOLUME 120, NUMBER 2 333
more than 0.5X side of head, anterior
border not reaching insertion of mandi-
ble. Ocelli large, prominent. Anterior
edge of clypeus convex. In lateral view,
clypeus shows small, blunt, beak-like
central lobe directed anteriorly. Mandi-
ble linear, with two large teeth. Antennal
scape ;1.3X as long as broad, cylin-
drical. Pedicel subglobose, broader than
scape or following flagellomere.
Mesosoma. Robust, elliptical. In lateral
view, mesonotum flat, at the same level as
the pronotum. Scutellum swollen and
strongly convex, higher than mesonotum.
Propodeum rounded, basal face strongly
convex transversely, only slightly convex
longitudinally, declivous face flat and per-
pendicular. Posterior margin of meta-
pleuron separated from propodeum by
a suture and ventral margins ofmetapleuron
fused to propodeum. Wing venation similar
to the male of S. invicta, as in Fig. 95.
Metasoma. Anterior face of petiole
gently sloping, posterior face parallel.
In lateral view, postpetiole globulose,
wider than petiole. Dorsum of petiole
with a strong median longitudinal im-
pression, forming two lateral lobes.
Petiole anteroposteriorly flattened, bi-
lobate. Postpetiole wider than petiole,
ventral surface flat. Postpetiolar spira-
cles high, strongly projected laterally.
Genitalia as in S. invicta (e.g. Fig. 75).
Coloration, Sculpturing, and Pilosity.
All sculpture lacking except for basal 0.25
of petiole and postpetiole, metapleuron
and sides of propodeum finely striate and
punctuated. Body smooth and polished.
Setae golden, suberect, distributed all over
the body. Mesonotal pubescence absent.
Color black except legs and gaster brown.
Wings and veins light brown.
Morphometric Measurements. L
;5.44, HW 1.02, VW 0.52, HL 0.8, EL
0.44, OD 0.11, OOD 0.12, LOW 0.11,
MOW 0.12, CD 0.29, MFC 0.26, EW
0.35, SL 0.12, SW 0.11, PDL 0.08, PEW
0.14, LF1 0.21, LF2 0.15, LF3 0.17, WF1
0.08, FL 0.41, FW 0.23, MW 0.96, DML
2.4, PL 0.6, PND 0.5, PH 0.43, PPL 0.48,
DPW 0.62, PPW 0.72, PHB 0.51, CI 1.28,
OI 0.79, REL 0.55, OOI 1.09, VI 0.52,
FCI 0.25, CDI 0.36, SI 0.12, SI2 0.27, SI3
0.8, FI 0.56, NI 0.83, PLI 0.72, PHI 0.89,
PWI 1.03, PPWI 1.5, PPWB 1.41.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.43 mm, width 0.45 mm) (Figs.
148, 151). Cranium slightly broader than
long (Figs. 148, 151). Antenna with 2 or
3 sensilla, each bearing spinule (Figs. 148,
151). Occipital setal row with 7–8 bifid
setae, base 0.5–0.8X total length of seta,
setae 0.07–0.16 mm long (Figs. 148,
150, 151). First setal row on vertex with
2 bifid setae, base;0.66X total length of
seta, 0.10 mm long (Figs. 148, 151).
Second setal row on vertex with 4 setae,
inner 2 setae simple, outer 2 setae with
bifid apices (base;0.66X length), 0.10–
0.15 mm long (Figs. 148, 151). Setae
ventral to antenna level simple, 0.15–
0.17 mm long (Figs. 148, 151). Clypeus
with row of 3–4 setae, inner setae shorter
than outer setae, 0.05–0.10 mm long
(Fig. 148). Labrum small, short (width 2X
length) (Figs. 148, 151). Labrum with 4–5
minute sensilla and 2 setae on dorsal sur-
face of each half and apical border with
3–6 sensilla on each half. Labrum with 2–
3 coarse isolated spinules near each ven-
trolateral corner. Straight medial portion
of mandiblewith 2–5 teeth that decrease in
size dorsally (Fig. 149). Maxilla with apex
conical, palpus peg-like with 5 sensilla,
each bearing one spinule. Galea conical
with 2 apical sensilla, each bearing one
spinule. Labium with patch of spinules
dorsal to each palpus, spinules coarse and
isolated or in short rows of 2–3. Labial
palpus slightly elevated with 5 sensilla,
each bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Body setae of 2 types.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON334
Simple setae (0.05–0.10 mm long) ar-
ranged in transverse row of 6–9 on ventral
surface of each thoracic somite and on
each of 3 anterior abdominal somites,
some with short denticulate tips. Bifid
setae (0.06–0.09 mm long) occur else-
where, base 0.5X length.
Length. Approximately 2.6–2.8 mm.
Material examined.—Argentina:
Missiones, Aristo´bulo del Valle, 23.
v.2015, 27°05.2359, 54°57.1689 (19 w).
Brazil: Parana´: “Pinhais, R. Rod. Dep.
Joao Leopoldo Jacomel”, 18.xi.2015,
-25.43045098, -49.20909698, G.
Camacho and D. Gotzek, PR15-036,
(4 w); “Curitiba, Barigui Park”, 19.
xi.2015, -25.42987799, -49.31599097,
G. Camacho and D. Gotzek, PR15-039,
(18 w); “Rt.BR-277, Campo Largo,
Metalurgica Gans factory, field and
roadside by factory”, 19.xi.2015,
-25.43349998, -49.41256902, G.
Camacho andD.Gotzek, PR15-051, (10w);
“Rt.BR-277, Campo Largo, Metalurgica
Gans factory, on hillside next to road;
;3m from PR15-067”, 19.xi.2015,
-25.43395202, -49.41203199, G.
Camacho and D. Gotzek, PR15-066,
(4 w); “S. Luis do Puruna˜, open gravel
field behind truck stop on Rt.BR-277”,
20.xi.2015, -25.47302401, -49.70426696,
G. Camacho and D. Gotzek, PR15-075,
(4 w); “S. Luis do Puruna˜, open gravel
field behind truck stop on Rt.BR-277”,
20.xi.2015, -25.47300699, -49.70436101,
G. Camacho and D. Gotzek, PR15-076,
(2 w); “Edge of Ponto Grossa, median of
Rt.PR-513”, 20.xi.2015, -25.14492497,
-50.14723303, G. Camacho and D. Gotzek,
PR15-082, (6 w); “Vila Velha N.P.,
Campos Gerais open shrubland”, 21.
xi.2015, -25.25196397, -50.008018, G.
Camacho and D. Gotzek, PR15-086,
(6 w); “Rt.BR-376, side of road”, 21.
xi.2015, -24.87010701, -50.44417997,
G. Camacho and D. Gotzek, PR15-093,
(2w); “Cascavel (Guarapuava, southeastern
suburb to Rt.PR-170)”, 24.xi.2015,
-25.392934, -51.49619398, G. Camacho
and D. Gotzek, PR15-153, (4 w); “Candoi,
empty lot in town center”, 24.xi.2015,
-25.56748403, -52.05006, G. Camacho
and D. Gotzek, PR15-161, (2 w); “Pinhao,
town park”, 24.xi.2015, -25.69448998,
-51.660301, G. Camacho and D. Gotzek,
PR15-165, (8 w); Rt.BR-277 btwn
Guarapuava+ Irati, 25.xi.2015, -25.31583399,
-51.19612, G. Camacho and D. Gotzek,
PR15-194, (6 w); National Forest Irati, 26.
xi.2015, -25.40887697, -50.57687396, G.
Camacho and D. Gotzek, PR15-211, (26
w); “Pinheiros, edge of soccer field”, 26.
xi.2015, -25.42351797, -50.55518403, G.
Camacho and D. Gotzek, PR15-224,
(2 w); Rt.BR-153 btwn Irati + Unia˜o d.
Vitoria, 26.xi.2015, -25.68580499,
-50.76397598, G. Camacho and D.
Gotzek, PR15-226, (4 w); Rt.BR-153 exit
to Rio Azul, 26.xi.2015, -25.70675304,
-50.78334597, G. Camacho and D.
Gotzek, PR15-228, (10 w); “Mallet, town
center, recently mowed field”, 26.xi.2015,
-25.88597297, -50.83851499, G. Camacho
and D. Gotzek, PR15-233, (16 w); “Paula
Freitas, in front of medical center”, 26.
xi.2015, -26.11710403, -50.82043698, G.
Camacho and D. Gotzek, PR15-240, (4 w);
Rondinha, 26.xi.2015, -26.171502,
-50.91157199, G. Camacho and D. Gotzek,
PR15-242, (2 w); Unia˜o da Vitoria, 26.
xi.2015, -26.20269299, -51.06220803, G.
Camacho and D. Gotzek, PR15-249, (2 w);
“Palmeira, Rt.BR-277”, 27.xi.2015,
-25.43500604, -49.991854, G. Camacho
and D. Gotzek, PR15-255, (4 w); Colonıˆa
Johannesdorf on Rt.BR-476, 27.xi.2015,
-25.742842, -49.76574504, G. Camacho
and D. Gotzek, PR15-264, (2 w), Rt.
BR-476 btwn Lapa + Sao Mateus do Sul,
27.xi.2015, -25.85078599, -49.94710797,
G. Camacho and D. Gotzek, PR15-268,
(10 w); “Rio Negro, Rt.BR-116”, 28.
xi.2015, -26.070288, -49.73545603, G.
Camacho and D. Gotzek, PR15-275, (4 w);
VOLUME 120, NUMBER 2 335
“Campo do Tenente, town center”, 28.
xi.2015, -25.97824599, -49.68351698, G.
Camacho and D. Gotzek, PR15-282, (6 w);
“Colombo, Rt.BR-476 to Tunas”, 29.
xi.2015, -25.32895703, -49.15940403, G.
Camacho and D. Gotzek, PR15-308,
(12 w); “Rt.BR-476, edge of Bocaiuva
do Sul”, 29.xi.2015, -25.19912797,
-49.11631904, G. Camacho and D. Gotzek,
PR15-317, (2 w); “Rt.BR-476, btwn
Bocaiuva do Sul + Tunas”, 29.xi.2015,
-25.18001899, -49.12016901, G. Camacho
and D. Gotzek, PR15-318, (6 w); “Tunas,
town center”, 29.xi.2015, -24.97498498,
-49.08486804, G. Camacho and D. Gotzek,
PR15-321, (14 w); “Rt.BR-476, btwn
Tunas + Bocaiuva do Sul”, 29.xi.2015,
-25.01404096, -49.07943397, G. Camacho
and D. Gotzek, PR15-330, (18 w);
“Colombo, town center, along Rt.BR-476”,
29.xi.2015, -25.30889997, -49.14433798,
G. Camacho and D. Gotzek, PR15-341,
(2 w); Rt 277@KM493; near Guaraniacu,
1998, -25.107, -52.867, G-72, (1 w); Rt 116
at Rio Negro, 1998, -26.10583333,
-49.7975, G-80, (2 w); Rt 277 @ KM 317;
at junction with Rt 373, 1998, -25.46,
-51.958, G-74, (1 w); Palmas, 2009,
-26.484151, -51.991450, E. Fox, Bra09-
22, (2 w). Brazil: Rio de Janeiro: Treˆs
Rios, 2009, -22.118277, -43.209538,
E. Fox, Bra09-15, (1 w); Itaipava, 2009,
-22.383333, -43.133333, E. Fox, Bra09-31,
(2 w); Rio de Janeiro University campus,
2009, -22.911267, -43.236059, E. Fox,
Bra09-68, (1 w).
Nomenclatural notes.—An unpublished
manuscript name, “S. altipunctata” (Pitts
2002), was used by Gotzek et al. (2007) in
reference to this species. Since that usage
occurred without the species being for-
mally described in a publication satisfying
the requirements of ICZN Article 8, the
namewas rendered unavailable as a nomen
nudum following Article 13 of the Code
(ICZN, 1999). Here we formally describe
this species as Solenopsis metallica.
Etymology.—This species is named for
one of its most common and conspicuous
color morphs, the bright, metallic orange
phase. It is also one of several authors’
favorite rock bands. The specific epithet is
a noun in apposition.
Distribution.—The type series of the
species was originally collected in the
highlands of Santa Catarina state, southern
Brazil. Further examination of material
collected in Rio de Janeiro State in 2008
andMisiones Province in 2015 also proved
to be S. metallica, suggesting a southeast-
ern Atlantic Forest range for the species. In
2015, extensive collections in Parana´ State
showed that the species is widely distrib-
uted in subtropical humid forest in the re-
gion. See Fig. 201.
Comments.—The major workers of
this species are easily distinguished from
others in this species-group by the long
scape failing to reach the vertexal margin
of the head, postpetiole sculpture in pos-
terior view with lower 0.25–0.33 trans-
versely rugose, upper surface glabrous and
shiny and the anterior projection on the
first gaster sternite visible in dorsal view.
Other distinguishing characters are present
on the gyne, including the greatly di-
verging clypeal carinae, the large pilig-
erous foveolae on the head andmesosoma,
the strongly to weakly defined striae be-
tween the ocelli, the lack of a median cell
due to the loss of the m-cu cross vein, and
the reduction in postpetiolar sculpturing.
Themajor workers of S. metallica can be
easily differentiated from their putative
sister species, S. weyrauchi. Solenopsis
metallica have 10–12 costulae on the
mandible that are obsolescent medially and
have larger piligerous foveolae on the head
and mesosoma. In comparison, the major
workers of S. weyrauchi have 5–6 complete
mandibular costulae and their cephalic fo-
veolae are smaller. The shape of the post-
petiole of theworkers is most similar to that
of S. saevissima, but is more coarsely
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON336
sculptured. The darker colored workers
appear bicolored, which is similar to the
color pattern of S. electra. The minor
workers (Fig. 17) of this species are usually
lighter than the majors, but can sometimes
have similar coloration. They also have
large, distinct foveolae on the head and
mesosoma, which is easily noticed. As with
the other fire ant species, however, the mi-
nors are difficult to identify. The larvae of
this species are unremarkable and are sim-
ilar to S. saevissima and S. invicta by having
bifid setae on the head capsule. The setae on
the head capsule are longer in this species,
however, than in S. invicta or S. saevissima.
In addition to the morphological
characters that define the species,
S. metallica can be differentiated in the
field by ecological and behavior char-
acteristics that are different from sym-
patric fire ant species. During collections
in Parana´ state in 2015, we observed that
S. metallica presents a less aggressive
response and sting to nest disturbance
than S. invicta and other fire ants, apart
from its usual bright orange or goldish
appearance to the naked eye. It appears
muchmore shade tolerant than S. invicta as
it builds nests underneath closed canopy.
The taxonomic distinctiveness of
S. metallica is also circumstantially
supported by genetic data. DNA sequence
data (mitochondrial: Shoemaker et al.
2006; Ross et al. 2010; nuclear: Gotzek
et al. 2007; Krieger and Ross 2005) and
a large panel of microsatellite and allo-
zyme data (Ross et al. 2010) clearly
distinguish individuals of this species
(alternately termed S. sp. “A”, “southern
highlands”, or “S. altipunctata” in those
studies) from other fire ant species.
Solenopsis daguerrei (Santschi)
(Figs. 86, 106, 108, 195–200)
Labauchena daguerrei Santschi 1930: 81.
[Holotype (?) gyne,males.ARGENTINA.
Buenos Aires Province. Rosas. F. C.
Sud. MACN]
Labauchena acuminata Borgmeier
1949: 208. [IMLA]
Solenopsis daguerrei: Ettershank 1966: 140.
Gyne.—Head: broader than long,
quadrate, wider anterior to eyes, sides of
head weakly convex from eyes to oc-
cipital angles, nearly straight anterior to
eyes. Occipital angles well defined (Fig.
195), lobate in lateral view (Fig. 196).
Vertex flattened posteriorly with narrow,
transverse impression just anterior to
occipital carina. Occipital furrow lack-
ing (Fig. 195). Frontal furrow lacking
(Fig. 195). Ocelli small, median ocel-
lus ventral to posterior margin of eyes
(Fig. 195). Clypeus not projecting,
lacking carinae or carinal teeth, ante-
rior margin straight. Mandible gently
curving, masticatory border with one
large tooth and usually rudiments of
two more teeth, with dorsal lobe dorsal
to teeth rudiments (Fig. 197). Eye convex,
ovate, midpoint of head reaches posterior
0.33 of eye. Antennal scape in repose
surpasses lateral ocellus. Antenna 11-seg-
mented. Pedicel ³ 2X length of second
flagellomere. First and second flag-
ellomere length each >1.5X their width.
Mesosoma. Elliptical, narrower than
head. In lateral view, mesonotum convex
anterior portion that greatly overhangs
pronotum, lobate (Fig. 196), posterior half
straight. Pronotumwider thanmesonotum.
Scutellum as high as mesonotum, flattened
with short, perpendicular posterior face.
Angle of propodeum well-defined, obtuse,
differentiation between basal and decli-
vous faces indistinct (Fig. 198). Meso-
sternum small, slightly rounded beneath.
Parapsidal lines absent. Posterior and
ventral margin of metapleuron fused to
pronotum. Propodeal spiracle much re-
duced in size (Fig. 198). Metasternal bi-
dentate median process present. Wing
VOLUME 120, NUMBER 2 337
venation reduced (Fig. 106), medial cell
lacking or barely discernable as such.
Metasoma. Petiolar node thick, dor-
sum somewhat flattened at obtuse angle,
appearing to have anterior median boss
on dorsum. Petiole ventrally with me-
dian carina on anterior 0.50. Postpetiole
lacking ventral transverse carina, only
slightly convex.
Coloration, Sculpturing, and Pilosity.
Sculpture lacking, body polished, except
posterior 0.25 of petiole finely striate.
Setae long (0.10–0.28 mm), golden,
semi-erect, somewhat longer on meso-
soma than elsewhere. Color yellow with
apex of mandibles and apices of meta-
soma segments 3–6 brown. Internal
margins of ocelli yellow.
Male.—Head. Trapezoidal (Fig. 199).
Eye very large, strongly convex, ovate,
occupying more than 0.5X side of head,
anterior border reaching insertion
of mandible (Fig. 199). Ocelli large,
prominent (Fig. 199). Anterior edge of
clypeus straight (Fig. 199). In lateral
view, clypeus shows small, blunt, beak-
like central lobe. Mandible linear, with
single apical tooth, lobe present dorsal to
tooth (Fig. 199). Antennal scape ;1.7X
as long as broad, cylindrical (Fig. 200).
Pedicel subglobose, broader than scape
or following flagellomere (Fig. 200).
Mesosoma. Robust, elliptical. In lat-
eral view, mesonotum swollen anteri-
orly, overhanging pronotum. Scutellum
convex, slightly higher than mesonotum.
Propodeum rounded, basal face strongly
convex transversely, only slightly convex
longitudinally, declivous face flat and
perpendicular. Posterior and ventral mar-
gins of metapleuron fused to propodeum.
Wing venation reduced (Fig 108), many
veins being nebulous.
Metasoma. Anterior face of petiole
gently sloping, posterior face abruptly
curved. In lateral view, postpetiole
elongate, slightly shorter than petiole.
Dorsum of both with slight median lon-
gitudinal impression. Petiole dorsolat-
erally rounded, not bilobate. Postpetiole
wider than petiole, ventral surface flat.
Genitalia reduced in form, digitus lack-
ing setae, aedeagus with few ventral
teeth (Fig. 86).
Coloration, Sculpturing, and Pilosity.
All sculpture lacking except for basal
0.25 of petiole and postpetiole finely
striate. Body smooth and polished. Setae
golden, suberect, length 0.10–0.16 mm,
mesonotum and petiolar nodes sparsely
pubescent. Mesonotal pubescence sparse
(as in Fig. 72). Color yellow except
vertex of head and gaster brown. Wings
and veins hyaline.
Material Examined.—See Appendix A.
Distribution.—The known range of S.
daguerrei extends from Buenos Aires
Province, Argentina northward, including
Uruguay, to Campo Grande, Brazil and
eastward to Sa˜o Paulo, Brazil (Fig. 203)
(Briano et al. 1997). Solenopsis daguerrei
seems to be generally sparse over most of
its range. They appear to be concentrated
in colonies only in certain areas (Briano
et al. 1997).
Comments.—The males and gynes of
this species are distinct from the other
members of the group by their colora-
tion, and the reduction in size, sculptur-
ing, and wing venation associated with
their socially parasitic existence. The
genitalia of the male are also distinct
from the other species by lacking setae
on the digitus, having a reduced number
of ventral setae on the volsella, and
having a reduced number of ventral teeth
on the aedeagus (Fig. 86).
Solenopsis daguerrei has been re-
ported to either kill the host gyne in
laboratory studies (Bruch 1930) or to
be an inquiline, allowing the host gyne
to live (Silveira-Guido et al. 1965).
Regardless of the outcome for the
host gyne, the parasite lowers the egg
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON338
production of the host colony and some
speculation has been made regarding its
use as a biological control agent (Jouvenaz
1990; Wojcik 1990). Regarding hosts, it
is reported to parasitize S. invicta,
S. richteri, S. macdonaghi, and S. quin-
quecuspis (Santschi 1930; Briano et al.
1997; Calcaterra et al. 2000). We found
S. daguerrei only in S. invicta colonies
during our extensive sampling in Bra-
zil and Argentina (see Appendix A).
Solenopsis electra Forel
(Figs. 39, 40, 107)
Solenopsis pylades electra Forel 1914:
397. [Syntype workers. ARGENTINA.
Salta. Jujuy. XI-913 (=1913). Schuer.
#129. MHNG.]
S. saevissima electra: Santschi 1916:
381.
S. (Solenopsis) saevissima electra:
Creighton 1930: 92. Worker, gyne.
S. saevissima saevissima cline S. sae-
vissima richteri (Bolivian variant):
Wilson 1952: 65. [MCZ.]
S. saevissima saevissima cline S. sae-
vissima richteri subsp. electra: Wilson
1952: 65. [MCZ.]
S. electra: Trager 1991: 192.
Worker.—Head subovate. Head
sculpture with small piligerous foveolae,
<0.01 mm in diameter. Median frontal
streak absent. Median ocellus in largest
major workers present. Mandibular cos-
tulae well developed throughout entire
length. In lateral view, pronotum low and
nearly flat to weakly convex. Meso-
notum with 20–25 setae. Promesonotal
suture in largest major workers gently
curved medially, never projecting up-
ward. Mesonotum weakly convex in lat-
eral view. Propodeum sculpture granulate
posteroventral to spiracle. Postpetiole
shape as high as or higher than broad.
Postpetiole sculpture in posterior view
with lower 0.66 transversely rugose,
granulate, upper surface glabrous and
shiny. Color of head, legs, antennae gen-
erally red yellow. Mesosoma and gaster
dark brown. T1 yellow anteriorly. Man-
dibles brown. Some specimens darker
brown black, with appendages slightly
lighter.
Gyne.—Head. Slightly broader to as
broad as long, quadrate, sides of head
convex from eyes to occipital angles,
straight anterior to eyes (Fig. 40). Eye
sometimes with 2–4 long setae pro-
truding from between ommatidia, setal
length >4X width of ommatidium. Ocelli
large, prominent (Fig. 40). Median
ocellus circular, lateral ocelli slightly
ovate (Fig. 40). Ocelli in more anterior
position on head (Fig. 40). Clypeus pro-
jecting, carinal teeth stout and sharp, ca-
rinae well defined, prominent between
antennal scrobes, slightly divergent ven-
trally (Fig. 40). Paracarinal teeth small,
indistinct to absent (Fig. 40). Median
clypeal tooth well developed (Fig. 40).
Approximately 0.50 of eye basal to mid-
length of head (Fig. 40).
Mesosoma. Parapsidal lines present
on posterior half of disk (Fig. 39).
Mesonotum without posteromedian
furrow. Metasternum with bidentate
median process. Wing venation as in
Fig. 107.
Metasoma. Lateral faces of post-
petiole weakly concave. Petiolar spiracle
normally not tuberculate. Postpetiolar
spiracles normally tuberculate.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae small, sparse, width
<0.01 mm in diameter, larger on head
than on thorax and abdomen. Pubes-
cence simple, golden and erect, longer
and denser on head than elsewhere,
longest on anterior edge of clypeus.
Mesonotum pubescence 0.16–0.25 mm,
longest pubescence on mesonotum 2X
VOLUME 120, NUMBER 2 339
longer than shortest pubescence. Man-
dible with 5–8 coarse, distinct costulae
present throughout entire length. Pro-
podeum with fine striae throughout (Fig.
39). Petiolar node basal 0.75 with striate,
dorsum polished. Postpetiolar node basal
0.50 with fine striae, dorsum polished.
Remaining integument smooth and pol-
ished. Color yellow with gaster red brown.
T1 with basal 0.50 yellow, remaining
segments yellow anterolaterally. Internal
margins of ocelli dark brown.
Morphometric Measurements. L
;6.2–6.5, HW 1.15–1.28, VW 1.09–
1.15, HL 1.20–1.30, EL 0.36–0.44, OD
0.15–0.21, OOD 0.09–0.12, LOW 0.10–
0.15, MOW 0.10–0.16, CD 0.15–0.19,
MFC 0.18–0.21, EW 0.25–0.34, SL
0.78–0.91, PDL 0.14–0.19, LF1 0.07–
0.11, LF2 0.05–0.10, LF3 0.07–0.10,
WF1 0.04–0.07, FL 0.92–1.05, FW
0.21–0.29, MW 1.21–1.33, DLM 2.15–
2.31, PRH 0.88–1.04, PL 0.56–0.68,
PND 0.45–0.56, PH 0.55–0.64, PPL
0.31–0.36, DPW 0.50–0.68, PPW 0.56–
0.64, PHB 0.32–0.45, N=2.
Male.—Unknown.
Fourth instar worker larva.—
Unknown.
Material Examined.—Various speci-
mens (FSCA).
Distribution.—The currently known
range of S. electra extends northward
from Santiago del Estero Province of
Argentina to Santa Cruz, Bolivia (Fig.
201). Trager (1991) lists a sample exam-
ined from Asuncio´n, Paraguay. Sampling
efforts between the known range and
Asuncio´n, Paraguay have not produced
any specimens of S. electra, so this record
may represent an introduction.
Comments.—The gyne of S. electra is
similar to S. pusillignis, S. saevissima,
and S. macdonaghi in coloration and in
the lack of mesonotal maculae. The gyne
of this species has a thinner petiolar
node, a smaller OOI, and a smaller body
size than those of S. saevissima and
S. macdonaghi. The gynes of S. electra
differ from the gynes of the sister spe-
cies, S. pusillignis, by having a smaller
OI, a more developed median clypeal
tooth, and a darker coloration of the
gaster.
The northern populations of S. electra
have much larger workers than the
southern populations, but the gynes of
these populations remain unchanged in
size. Males were not available for ex-
amination for this study, but Trager
(1991) describes them as being relatively
small compared to males of the rest of
the species-group.
Solenopsis interrupta Santschi
(Figs. 21, 22, 47, 52, 56, 57, 73, 74,
92, 93, 132, 133, 152–154, 157)
Solenopsis saevissima var. interrupta
Santschi 1916: 397. [Syntype (?)
workers. ARGENTINA. La Rioja.
Bajo Hondo. NHMB.]
S. (Solenopsis) saevissima interrupta:
Creighton 1930: 89 (In part.).
S. interrupta Wilson 1952: 61 (In part.).
Worker.—Head weakly to strongly
cordate (Fig. 132). Head and mesosomal
sculpture with small piligerous foveolae,
<0.01 mm in diameter. Median frontal
streak mostly absent, but sometimes
distinctly darkened. Median ocellus in
largest major workers absent (Fig. 133).
Mandibular costulae dense, present
throughout, rarely partially obsolescent.
Mesonotum with 20–25 setae (Fig. 132).
Promesonotal suture in largest major
workers gently curved medially, never
projecting upward (Fig. 132). Propodeum
sculpture glabrous posteroventral to spi-
racle (Fig. 132). Postpetiole shape as high
as or higher than broad. Postpetiole
sculpture in posterior view weakly
transversely rugose, weakly granulate,
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON340
reaches dorsum only in largest workers.
Color generally red yellow to brown
yellow, with head and mesosoma dorsum
darker. Gaster dark brown. T1 with
maculation red yellow to brown yellow.
Gyne.—Head: broader than long,
quadrate, slightly wider dorsal to eyes
than ventral to them, sides of head con-
vex from eyes to occipital angles,
straight to nearly straight ventral to eyes
(Fig. 22). Eyes sometimes with 3–4 setae
protruding from between ommatidia,
setal length £3X width of ommatidium.
Ocelli large, prominent (Fig. 22). Median
ocellus circular, lateral ocelli slightly
ovate (Fig. 22). Clypeus projecting, cari-
nal teeth stout and sharp, carinae well
defined, less so dorsally, slightly divergent
ventrally, edge of clypeus between carinae
with shallow concave depression, de-
pression deepest between carinal teeth
(Fig. 22). Paracarinal teeth poorly defined
to absent (Fig. 22). Median clypeal tooth
usually well developed; sometimes less
developed (Fig. 22). Approximately 0.50
of eye dorsal to midpoint of head (Fig. 22).
Mesosoma. Parapsidal lines present
on posterior half of disk (Fig. 21).
Mesonotum with indistinct to distinct
median furrow, usually on posterior
0.25–0.33 of disk. Propodeum some-
times with median longitudinal de-
pression. Median bidentate process
present on metasternum. Wing venation
as in Fig. 92.
Metasoma. Lateral faces of post-
petiole weakly concave to straight sided.
Petiolar spiracle tuberculate in some
cases. Postpetiolar spiracle usually not
tuberculate.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae moderate to small,
sparse, width 0.01–0.03 mm in diameter
on head, smaller on meso- and meta-
soma. Pubescence golden and erect,
longer and denser on head than else-
where, longest on anterior edge of
clypeus. Pubescence darker on darkly
maculated areas. Mesosoma with longest
pubescence (length 0.30 mm or greater)
3X longer than shortest pubescence.
Mandible with several coarse, 6–8, dis-
tinct costulae present throughout. Pro-
podeum with fine striae posteriorly,
anterior 0.25 polished to finely striate.
Petiolar node posterior surface with
lower 0.75 coarsely striate, dorsum
finely striate. Postpetiolar node posterior
surface with middle 0.50 striate (with 7–
10 striae), finely granulate, lower 0.25
coarsely granulate (Fig. 47). Inter-
foveolar spaces on head finely striate
when piligerous foveolae are large. Re-
maining integument smooth and pol-
ished. Two color varieties exist. Dark
form brown with katepisternum, meta-
soma and medial area of legs dark
brown. Light form orange to yellow or-
ange, except vertex and T2-4, T1 later-
ally and apically and sternites apically
dark brown. Light form also with pos-
terior margin of orange maculation of T1
distinct. Both color forms with dark
brown maculations anteriorly on prono-
tum, anteromedian area of mesonotum,
area around parapsidal lines, sometimes
on median area of axillae, anteromedian
and triangular posteromedian area of
scutellum, medially on anepisternum,
and medially and laterally on propo-
deum (Fig. 52). Internal margins of
ocelli dark brown. Median frontal streak
present (as in Fig 50). Wings hyaline
with pale yellow to hyaline veins.
Morphometric Measurements. L
;7.8–8.4, HW 1.35–1.60, VW 0.89–
1.01, HL 1.20–1.35, EL 0.40–0.51, OD
0.10–0.15, OOD 0.15–0.20, LOW 0.10–
0.12, MOW 0.10–0.12, CD 0.15–0.20,
MFC 0.18–0.23, EW 0.30–0.35, SL
0.90–1.10, PDL 0.15–0.20, LF1 0.10–
0.12, LF2 0.08–0.11, LF3 0.08–0.10,
WF1 0.06–0.08, FL 1.10–1.21,
FW 0.21–0.31, MW 1.30–1.40, DLM
VOLUME 120, NUMBER 2 341
2.49–2.62, PRH 1.00–1.11, PL 0.59–
0.75, PND 0.55–0.65, PH 0.60–0.72,
PPL 0.30–0.40, DPW 0.61–0.82, PPW
0.59–0.73, PHB 0.41–0.50, N=5.
Male.—Head. Eyes sometimes with
3–4 setae protruding from between om-
matidia, setal length £3X width of om-
matidium. Ocelli large and prominent,
median ocellus circular, lateral ocelli
elliptical (Fig. 57). In lateral view,
clypeus with blunt, central lobe with
indistinct anterior transverse carina.
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally
(Fig. 56). Metapleuron broad almost
0.66 as wide as high (Fig. 56). Wing
venation as in Fig. 93.
Metasoma. In cephalic view, dorsum
of node transverse to having weak median
depression and weakly bilobate. Petiolar
and postpetiolar spiracles slightly tuber-
culate to not tuberculate. Genitalia as in
Fig. 74.
Coloration, Sculpturing, and Pilosity.
Pubescence sparse, yellow to yellow
orange, erect to suberect, not of uniform
length over body (0.10–0.35 mm long),
longer on gena and vertex. Mesonotal
pubescence dense (Fig. 73). Base of
propodeum striato-granulate. Propo-
deum with anteromedial area glabrous.
Area between eye and insertion of an-
tenna (Fig. 57), and lateral faces of
scutellum finely striate. Area between
ocelli granulate. Remainder of head
weakly to coarsely granulate throughout,
shagreened in some cases (Fig. 57).
Lower surface of petiolar nodes coarsely
striato-granulate, dorsum finely striato-
granulate. Postpetiole often with fine
striations present dorsomedially. Meta-
pleuron with dorsal longitudinal region
finely striate. Gena granulate. Remain-
ing integument smooth and polished.
Color red brown to dark brown. Mandi-
ble brown anteriorly changing to yellow
brown at apex. Flagellum yellow brown
and legs segments brown medially
grading to yellow towards base and
apex.
Morphometric Measurements. L
;5.6–6.0, HW 1.00–1.10, VW 0.30–
0.55, HL 0.81–0.92, EL 0.40–0.51, OD
0.10–0.15, OOD 0.15–0.20, LOW 0.11–
0.14, MOW 0.11–0.15, CD 0.15–0.25,
MFC 0.15–0.21, EW 0.32–0.40, SL
0.15–0.20, SW 0.10–0.15, PDL 0.05–
0.10, PEW 0.11–0.15, LF1 0.20–0.25,
LF2 0.13–0.16, LF3 0.16–0.22, WF1
0.08–0.10, FL 1.09–1.22, FW 0.20–0.30,
MW 1.35–1.50, DLM 2.30–2.51, PRH
0.90–1.00, PL 0.60–0.75, PND 0.50–
0.65, PH 0.39–0.52, PPL 0.29–0.41,
DPW 0.60–0.71, PPW 0.55–0.75, PHB
0.18–0.30, N=6.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.44 mm, width 0.51 mm) (Figs.
152, 157). Cranium slightly broader than
long (Figs. 152, 157). Antenna with 2 or
3 sensilla, each bearing spinule (Figs.
152, 157). Occipital setal row with 8–12
bifid setae, base 0.5 to 0.8X total length
of seta, 0.067–0.010 mm long (Figs. 152,
157). First setal row on vertex with 1–2
bifid setae, base ;0.66X total length of
seta, 0.07–0.09 mm long (Figs. 152,
157). Second setal row on vertex with 4
simple setae, 0.13 mm long. Setae ventral
to antenna level simple, 0.15–0.21 mm
long (Figs. 152, 157). Clypeus with
transverse row of 4 setae, inner setae
shorter than outer setae, 0.07–0.12 mm
long (Figs. 152, 157). Labrum small,
short (breadth 2X length) (Fig. 152). La-
brumwith 4–6minute sensilla and 2 setae
on dorsal surface of each half and apical
margin with 5–6 sensilla on each half.
Each half of epipharynx with 2–4 isolated
sensilla. Straight medial portion of man-
dible with 2–5 teeth that decrease in size
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON342
dorsally (Fig. 154). Maxilla with apex
conical, palpus peg-like with 5 sensilla,
each bearing one spinule. Galea conical
with 2 apical sensilla, each bearing one
spinule. Labium with patch of spinules
dorsal to each palpus, spinules in short rows
of 2–3. Labial palpus slightly elevated with
5 sensilla, each bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Body setae of 2 types.
Simple setae (0.05–0.11 mm long) ar-
ranged in transverse row of 5–10 on
ventral surface of each thoracic somite
and on each of 3 anterior abdominal
somites, some with short denticulate
tips. Bifid setae (0.07–0.10 mm long)
occur elsewhere, base 0.5–0.75X length
(Fig. 153). Some bifid setae on thoracic
dorsum with base 0.33X length of seta.
Length. 3.2–3.4 mm.
Material examined.—Various speci-
mens (FSCA). Also, see Appendix A.
Distribution.—There is some ques-
tion concerning the exact type locality
for S. interrupta. Santschi (1916) merely
lists the type locality as “Argentine: Bajo
Hondo, Monte Hermeso”. But there are
at least two locations in Argentina called
Bajo Hondo. Buren (1972) placed the
type locality in Buenos Aires Province
and he considered the nominal S. inter-
rupta range to span Uruguay and Buenos
Aires, Entre Rios, Santa Fe Provinces,
Argentina. He excluded the northwest-
ern Argentinian and Bolivian forms from
the species. Trager (1991) placed the
type locality in La Rioja Province, since
he considered Buenos Aires to be well
outside the range of his concept of the
species (Cordoba and Mendoza Prov-
inces in Argentina northward into
Bolivia (Fig. 202)) and he considered
Santschi’s description to fit well within
his image of S. interrupta. Here, we
follow Trager’s (1991) interpretation.
Comments.—The gynes of S. inter-
rupta superficially resemble S. pythia
and S. metallica in both coloration and
sculpture of the head. Both S. pythia and
S. metallica have other derived charac-
ters, however, and thus are easily dis-
tinguished from S. interrupta.
The gynes of S. interrupta and S. richteri
are similar in coloration and both some-
times have a distinct orange tergal macu-
lation with a demarcated posterior margin.
In many cases, the gynes of these two
species are difficult to differentiate, but
they may be separated by the sculpture of
the postpetiole. The gynes of S. interrupta
are typically slightly lighter in coloration.
In addition, the OOI of S. interrupta gynes
is much greater than that of the S. richteri
gynes. The workers of these species, how-
ever, are relatively easy to separate from the
other members of this species-group.
The male is dark in coloration as are
males of most species in this group. The
pubescence of the males is longer and
denser than that of S. saevissima males.
Often, the head of the male is shagreened
as it is in S. invicta males.
The larvae of S. interrupta are similar
to those of S. invicta and S. saevissima.
They differ, however, in the size and
shape of the body setae. Also, the setae
ventral to the antennal level are typically
longer in S. interrupta than in S. invicta
or S. saevissima.
Solenopsis invicta Buren
(Figs. 23, 24, 42, 58, 59, 75, 94, 95, 134,
135, 167, 160–164)
Solenopsis saevissima var. wagneri
Santschi 1916: 380. [Syntype workers.
ARGENTINA. Santiago de Estero.
Near Icano. Wagner. NHMB.] (Name
suppressed in accord with ICZN 1976
(2001) as proposed by Shattuck, Porter,
and Wojcik (1999).)
S. saevissima saevissima cline S. saevissima
richteri: Wilson 1952: 65. [MCZ.]
VOLUME 120, NUMBER 2 343
S. invicta Buren 1972: 9. Worker, gyne,
male. [NMNH.] (Name conserved
(ICZN 2001)).
Worker.—Head subquadrate to weakly
cordate (Fig. 135). Head of largest speci-
mens cordate. Sculpture of head and
mesosomal dorsum with small piligerous
foveolae, <0.01 mm in diameter. Median
frontal streak present. Median ocellus in
largest major workers absent (Fig. 135).
Mandibular costulae absent medially, dis-
tinct apically and basally along outer
border. Mesonotum with 20–25 setae.
Mesonotum with anteromedian margin in
largest major workers gently curved.
Mesonotum in lateral view convex
(Fig. 134). Propodeum sculpture glabrous
posteroventral to spiracle (Fig. 134).
Postpetiole shape in posterior view width
greater than height. Postpetiole in poste-
rior view with lower 0.66 or greater
transversely rugose to punctate-rugose,
extreme dorsum nitid, granulate. Color
generally with head and mesosoma yellow
red to dark red brown, gaster brown, T1
with maculation yellow red to concolorous
with surrounding integument.
Gyne.—Head. Slightly broader than
long, quadrate, wider dorsal to eyes than
ventral to them, sides of head convex from
eyes to occipital angles, straight to nearly
straight ventral to eyes (Fig. 24). Eyes
sometimes with 2–10 setae protruding
from between ommatidia, setal length
£3X width of ommatidium. Median ocel-
lus large, prominent, circular (Fig. 24).
Lateral ocelli moderate to large, slightly
ovate (Fig. 24). Clypeus projecting, carinal
teeth stout and sharp, carinae well defined,
less so dorsally, slightly divergent ven-
trally (Fig. 24). Paracarinal teeth small,
sometimes poorly defined. Median clypeal
tooth well developed (Fig. 24). Approxi-
mately 0.50 of eye dorsal to midpoint of
head (Fig. 24). Antennal scape in repose
surpasses lateral ocellus.
Mesosoma. Parapsidal lines present
on posterior 0.50 of disk (Fig. 23).
Mesonotum with indistinct, median fur-
row on posterior one-sixth or less.
Bidentate median process present on
metasternum (Fig. 23). Wing venation as
in Fig. 94.
Metasoma. Lateral faces of post-
petiole slightly concave to wider ven-
trally. Petiolar and postpetiolar spiracles
slightly tuberculate to not tuberculate.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae small, sparse, width
<0.01 mm in diameter, larger on head
than on thorax and abdomen. Pubes-
cence simple, golden and erect, longer
and denser on head than elsewhere,
longest on anterior edge of clypeus.
Mesosoma with longest pubescence
(length £0.25 mm) 2X longer than
shortest pubescence (Fig. 23). Mandible
with 9–11 fine, distinct, costulae, some-
times costulae obsolescent medially.
Propodeum with fine striae throughout
(Fig. 23). Petiolar nodes with lower 0.75
finely striate; granulate throughout.
Postpetiole usually with 12–18 stria-
tions, often transverse (Fig. 41), other
times appearing to create swirling or
circular patterns. Remaining integument
smooth and polished. Color varies from
red brown to brown red on dorsum of
head, dorsum of thorax, and katepis-
ternum of mesopleuron. Gaster brown.
Sometimes on lighter colored individuals,
bases of T1 and S1 are somewhat orange
blending to brown apically. Brown macu-
lations sometimes present anteromedially
and on parapsidal lines (as in Fig. 52).
Median streak present (as in Fig. 50),
weak, sometimes indistinct or absent. In-
ternal margins of ocelli often dark brown.
Morphometric Measurements. L
;5.9–8.3, HW 1.30–1.46, VW 0.66–
0.88, HL 1.18–1.43, EL 0.38–0.49, OD
0.10–0.18, OOD 0.19–0.26, LOW 0.08–
0.15, MOW 0.16–0.24, CD 0.15–0.22,
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON344
MFC 0.15–0.25, EW 0.25–0.48, SL
0.78–1.11, PDL 0.13–0.25, LF1 0.08–
0.14, LF2 0.07–0.10, LF3 0.07–0.12,
WF1 0.06–0.11, FL 0.94–1.26, FW
0.22–0.36, MW 1.14–1.48, DLM 2.42–
2.73, PRH 0.88–1.19, PL 0.72–0.83,
PND 0.56–0.84, PH 0.57–0.78, PPL
0.24–0.42, DPW 0.51–0.74, PPW 0.71–
0.77, PHB 0.26–0.48, N=25.
Male.—Head. Eyes sometimes with
2–10 setae protruding from between
ommatidia, setal length £3X width of
ommatidium. Ocelli large and prom-
inent, elliptical (Fig. 59).
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally.
Metapleuron not broad, ;0.33 as wide
as high, sometimes with transverse pos-
terior carina (Fig. 58). Wing venation as
in Fig. 95.
Metasoma. In cephalic view, dorsum
of node with shallow to deep median
impression and weakly to strongly bilo-
bate. Petiolar and postpetiolar spiracles
distinctly tuberculate to not tuberculate.
Genitalia Fig. 75.
Coloration, Sculpturing, and Pilosity.
Pubescence short, sparse, yellow to brown,
erect to suberect (0.20–0.30 mm), longest
on gena and vertex. Mesonotal pubes-
cence dense (as in Fig. 73). Propodeum
with base striato-granulate, medially finely
granulate (Fig. 58). Area between eye and
insertion of antenna, posterior portion of
metapleuron, lateral faces of scutellum, and
base of petiolar node granulate to striato-
granulate (Fig. 58). Posterior surface of
postpetiolar node granulate throughout,
rugae present dorsomedially. Area between
ocelli weakly to coarsely striato-granulate
(Fig. 58). Gena coarsely rugose to coarsely
striato-granulate. Head often completely
granulate, shagreened, dull. Remaining in-
tegument smooth and polished. Color red
brown to black with antenna completely
yellow, sometimes scape and pedicel
brown. Mandibles brown to light brown.
Morphometric Measurements. L
;5.4–6.3, HW 0.91–1.08, VW 0.30–
0.40, HL 0.67–0.83, EL 0.37–0.53, OD
0.06–0.11, OOD 0.18–0.26, LOW 0.09–
0.18, MOW 0.10–0.17, CD 0.16–0.24,
MFC 0.13–0.18, EW 0.28–0.39, SL
0.16–0.20, SW 0.09–0.14, PDL 0.06–
0.10, PEW 0.10–0.15, LF1 0.10–0.17,
LF2 0.13–0.15, LF3 0.12–0.16, WF1
0.07–0.10, FL 1.00–1.15, FW 0.15–0.20,
MW 1.20–1.68, DLM 2.27–2.64, PRH
0.78–1.04, PL 0.62–0.69, PND 0.54–
0.61, PH 0.44–0.56, PPL 0.20–0.28,
DPW 0.55–0.71, PPW 0.58–0.69, PHB
0.14–0.28, N=25.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.50 mm, width 0.54 mm) (Figs.
160, 162). Cranium slightly wider than
long (Figs. 160, 162). Antenna with 2
or 3 sensilla, each with 1 spinule. In-
tegument of head with minute spinules.
Occipital setal row normally with 6–8
bifid setae, base ;0.66X total length of
seta, setae 0.08–0.10 mm long (Figs.
160, 162). First setal row on vertex with
2 bifid setae, base;0.66X total length of
seta, 0.05–0.07 mm long (Figs. 160,
162). Second setal row on vertex with
4–6 simple setae, ;0.10 mm long (Figs.
160, 162). Setae anterior to antenna level
simple, 0.08–0.14 mm long (Figs. 160,
162). Clypeus with transverse row of 4
setae, inner setae shorter than outer se-
tae, 0.06–0.08 mm long (Figs. 160, 162).
Labrum small, short (width 2.5X
length). Labrum with 4–6 minute sen-
silla and 2 setae on dorsal surface of
each half and apex with 4–6 sensilla on
each half. Each half of the epipharynx
with 2–3 isolated and 2 contiguous sen-
silla. Straight medial portion of mandi-
ble with 2–5 teeth that decrease in size
dorsally (Fig. 160). Maxilla with apex
VOLUME 120, NUMBER 2 345
conical, palpus peg-like with 5 sensilla,
each bearing one spinule (Fig. 160).
Galea conical with 2 apical sensilla
bearing spinules (Fig. 160). Maxilla with
sclerotized band between cardo and sti-
pes. Labium with patches of spinules
dorsal to each palpus, in 2–3 rows. La-
bial palpus slightly elevated with 5 sen-
silla, each bearing one spinule.
Body. Stout. Spiracles small, first
spiracle larger than others. Body setae of
2 types. Simple setae (0.06–0.11 mm
long) arranged in transverse row of 6–12
on ventral surface of each thoracic so-
mite and on each of 3 anterior abdominal
somites, some with short denticulate
tips. Bifid setae (0.06–0.09 mm long)
occur elsewhere, base ;0.5X length
(Fig. 161).
Length. About 3.1 mm (Fig. 164).
Material examined.—Various speci-
mens (FSCA). Also, see Appendices A
and B.
Distribution.—The range of Sol-
enopsis invicta in South America cur-
rently extends from as far north as Porto
Velho, Rondoˆnia State, Brazil and east-
ward from Peru and Bolivia to Cuiaba´,
Mato Grosso State, Brazil, southward to
Santiago del Estero Province of Argen-
tina, through Uruguay to Sa˜o Paulo
State, Brazil (Fig. 203). Its range in
North America includes the Gulf States
west to Texas. It is found sporadically in
New Mexico and Arizona and apparently
is well established in California. It re-
cently has been introduced to Australia,
Taiwan, China, and Japan (Henshaw et al.
2005; Ascunce et al. 2011). A compre-
hensive assessment of genetic variation
for colonies sampled from 75 geographic
sites worldwide revealed that at least nine
separate introductions of S. invicta oc-
curred into newly invaded areas and that
the main southern U.S. population is
probably the source of these secondary
introductions (Ascunce et al. 2011).
Comments.—Although it was dis-
covered that the name S. wagneri has
priority over S. invicta (Bolton 1995),
the International Commission of Zoo-
logical Nomenclature ruled that the
name S. invicta is to be conserved in
order to maintain stability and continuity
(ICZN 2001).
As noted with the workers (Trager
1991; J. Pitts and K. R. Ross, pers. obs.),
the gynes are highly variable in color.
The darker variants of gynes are found in
southeastern Brazil to Uruguay and Ar-
gentina and are associated with the
darker workers. A lighter variant occurs
in the northern area of the species’ range.
The gynes and workers of these colonies
are also similar in coloration. A third
variant, a light orange form, is found in
the Pantanal region of Brazil. This form
has larger workers and gynes. No mor-
phological differences could be found
between these forms, other than size and
coloration.
The darker colored gynes of S. invicta
look most similar to S. megergates and S.
quinquecuspis. However, the CI and OI
of S. invicta gynes are normally smaller
than those of S. megergates and the OI
of S. invicta is normally smaller than that
of S. quinquecuspis. The lighter gynes of
S. invicta look similar to S. richteri and
S. interrupta. The gynes of S. interrupta
normally are lighter in coloration than
S. invicta, have larger cephalic foveolae,
and sometimes have distinct striations
between the foveolae. The OOI of
S. invicta gynes is normally greater than
that of S. richteri, and the postpetiole of
S. invicta gynes has straight sides, unlike
the concave sides of S. richteri. In many
cases, the sculpture of the mandible and
postpetiole can help separate S. invicta
gynes from similar species. The gynes
of S. invicta normally have the most
densely sculptured postpetiole compared
to the other species.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON346
The male of S. invicta is dark in col-
oration and is similar to most of the other
darker species. The pubescence of the
S. invicta male is longer and denser than
that of S. saevissima. Sometimes the
head of the S. invicta male is shagreened
as in S. interrupta. The gena of the male
is much more sculptured than in other
species. In moderate to extreme forms,
this feature is easily recognized and it
may be autapomorphic for S. invicta.
Allozyme, microsatellite, and mito-
chondrial DNA data suggest that the
current concept of S. invicta might ac-
tually represent a group of several
cryptic species (Ross and Shoemaker
2005; Shoemaker et al. 2006; Ross et al.
2007). A thorough examination of S.
invicta adults from genetically distinct
populations revealed no apparent mor-
phological differences. In one colony of
S. invicta (colony O-18, see Appendix
A), the larvae differed from typical S.
invicta both in size and setal type. This
colony was collected in close proximity
to typical S. invicta and the adults do not
differ from typical S. invicta.
Fourth instar worker larva (O-18).—
Head. Large, subpyriform in anterior
view. Cranium slightly broader than long.
Antenna with 2 or 3 sensilla, each bearing
spinule. Integument of head with minute
spinules. Occipital setal row with 4–6
setae (0.06–0.08 mm long), median pair
simple, other setae bifid with base 0.66–
0.75X total length of seta. First setal row
on vertex with 2 simple setae,;0.09 mm
long. Second setal row on vertex with
2 simple setae, 0.10–0.12 mm long. Se-
tae ventral to antenna level simple, 0.09–
0.12 mm long. Clypeus with transverse
row of 4 setae, inner setae shorter than
outer setae, 0.05–0.10 mm long. Labrum
small, short (width 1.8X length), slightly
narrowed medially. Labrum with 5 min-
ute sensilla and 2 setae on anterior sur-
face of each half and ventral border with
6 sensilla on each half. Each half of
posterior surface of labrum with 2–3
isolated sensilla. Straight medial portion
of mandible with 2–5 teeth that decrease
in size basally. Maxilla with apex coni-
cal, palpus peg-like with 5 sensilla, each
bears one spinule. Galea conical with 2
apical sensilla. Labium with patch of
spinules dorsal to each palpus, spinules
coarse and isolated or in short rows of
2–3. Labial palpus slightly elevated with
5 sensilla, each bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Body setae of 2 types.
Simple setae (0.07–0.12 mm long) ar-
ranged in transverse rows of 6–9 on
ventral surface of each thoracic somite
and on each of 3 anterior abdominal
somites, some with short denticulate
tips. Bifid setae (0.08–0.12 mm long)
occur elsewhere, base ;0.33X length,
branches more or less perpendicular to
base, tips recurved.
Length. 2.7–2.9 mm.
Solenopsis macdonaghi Santschi
(Figs. 25, 26, 60, 61, 76, 77, 96, 97, 136,
137, 165–169)
Solenopsis saevissima var. macdonaghi
Santschi 1916: 379. [Syntype workers,
gynes. ARGENTINA. Entre Rios.
Estacio´n Sosa. MacDonagh. NHMB.]
S. geminata pylades: Bruch 1916: 313.
S. (Solenopsis) saevissima interrupta:
Creighton 1930: 89.
S. macdonaghi: Trager 1991: 179.
Worker.—Head broad, cordate (Fig.
137). Head sculpture with small piligerous
foveolae, approximately 0.01 mm in di-
ameter. Median frontal streak absent.
Median ocellus in largest major workers
present. Mandibular costulae obsoles-
cent, except apically, rarely complete.
Mesonotum with 20–25 setae (Fig. 136).
VOLUME 120, NUMBER 2 347
Promesonotal suture in largest major
workers angulate medially, sometimes
projecting upward (Fig. 136). Meso-
notum in lateral view weakly convex.
Propodeum sculpture glabrous poster-
oventral to spiracle (Fig. 136). Propo-
deum in largest major workers curves
upward from metanotal groove higher
than flattened posterior portion, appear-
ing as anterior raised portion in lateral
view. Postpetiole shape much broader
than high. Postpetiole in posterior view
lacking transverse rugae or with rugae
medially, normally granulate to dorsum.
Color generally red yellow to brown
yellow, gaster dark brown, T1 with red
yellow to brown yellow maculation.
Gyne.—Head. Slightly wider than
long, quadrate, sides of head convex
from eyes to occipital angles, straight to
nearly straight ventral to eyes (Fig. 26).
Eyes sometimes with 3–4 setae pro-
truding from between ommatidia, setal
length £3X width of ommatidium. Ocelli
large, prominent (Fig. 26). Median
ocellus circular, lateral ocelli slightly
ovate (Fig. 26). Clypeus projecting,
carinal teeth stout and sharp, carinae
well defined, slightly divergent ventrally,
edge of clypeus between carinae with
shallow concave depression, depression
deepest between carinal teeth (Fig. 26).
Paracarinal teeth small, indistinct (Fig.
26). Median clypeal tooth poorly
developed, usually absent (Fig. 26).
Approximately 0.50 of eye dorsal to
midpoint of head (Fig. 26).
Mesosoma. Parapsidal lines present on
posterior 0.50 of disk (Fig. 25). Meso-
notum with indistinct, median furrow
present on posterior 0.25 or less. Bi-
dentate median process present on meta-
sternum. Wing venation as in Fig. 96.
Metasoma. Lateral faces of postpetiole
straight to weakly convex. Petiolar and
postpetiolar spiracles tuberculate in some
cases.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae small, sparse, width
<0.01 mm in diameter. Pubescence
simple, golden and erect, longer and
denser on head than elsewhere, longest on
anterior edge of clypeus. Mesosoma with
longest pubescence (length >0.30 mm)
3X longer than shortest pubescence
(Fig. 25). Mandible with 10–12 fine,
distinct costulae present throughout.
Propodeum with fine striae throughout
(Fig. 25). Petiolar nodewith lower 0.75 of
surface finely striate, dorsum polished.
Postpetiole node with striations on lower
0.75 of surface somewhat coarser, 7–9
striae, finely granulate, dorsum polished
(Fig. 41). Remaining integument smooth
and polished. Color varies from orange to
dark orange and legs orange to yellow
orange with T1-T4 brown laterally and
apically. Basal orange coloration of T1
blends evenly to brown apically. Meso-
notum maculations absent on parapsidal
lines, although sometimes present ante-
romedially. Internal margins of ocelli not
dark brown. Median frontal streak absent.
Morphometric Measurements. L
;6.9–7.5, HW 1.42–1.46, VW 0.85–
0.92, HL 1.22–1.34, EL 0.41–0.46, OD
0.12–0.15, OOD 0.23–0.25, LOW 0.08–
0.11, MOW 0.10–0.14, CD 0.15–0.17,
MFC 0.18–0.20, EW 0.30–0.34, SL
0.95–1.05, PDL 0.21–0.25, LF1 0.10–
0.14, LF2 0.07–0.11, LF3 0.07–0.09,
WF1 0.07–0.09, FL 1.20–1.25, FW
0.26–0.27, MW 1.35–1.45, DLM 2.48–
2.84, PRH 1.02–1.09, PL 0.73–0.82,
PND 0.54–0.70, PH 0.65–0.70, PPL
0.32–0.38, DPW 0.65–0.70, PPW 0.70–
0.75, PHB 0.35–0.40, N=7.
Male.—Head. Eyes normally with 2–4
setae protruding from between ommatidia,
setal length £3X width of ommatidium.
Ocelli moderate to large, prominent,
elliptical (Fig. 61).
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON348
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally.
Metapleuron not broad, ;0.66 as wide
as high (Fig. 60). Wing venation as in
Fig. 97.
Metasoma: In cephalic view, dorsum
of node with deep median depression,
bilobate. Petiolar and postpetiolar spi-
racles distinctly tuberculate to not tu-
berculate. Genitalia as in Figs. 76 and
77.
Coloration, Sculpturing, and Pilosity.
Pubescence short, thin, yellow, erect to
suberect and of uniform length over
body (0.25–0.30 mm), longest on gena
and vertex. Mesonotal pubescence dense
(as in Fig. 73). Propodeum with base
striato-granulate, medially finely granu-
late. Area between eye and insertion of
antenna, pronotum posteriorly and base
of petiolar node coarsely granulate.
Posterior surface of postpetiolar node
granulate throughout. Area between
ocelli and vertex finely striato-granulate
to granulate (Fig. 61). Areas antero-
lateral to median ocellus usually gla-
brous (Fig. 61). Gena coarsely granulate,
less often rugose anterior to occipital
carina, never rugose throughout. Meta-
pleuron and lateral faces of scutellum
striato-granulate. Remaining integument
smooth and polished. Color red brown to
black, antennae and legs yellow brown.
Mandibles yellow, extreme apex brown.
Morphometric Measurements. L;5.7–
6.6, HW 1.00–1.20, VW 0.34–0.39, HL
0.74–0.89, EL 0.40–0.52, OD 0.08–0.11,
OOD 0.15–0.28, LOW 0.10–0.18, MOW
0.13–0.16, CD 0.16–0.22, MFC 0.13–
0.18, EW 0.34–0.41, SL 0.14–0.18, SW
0.09–0.11, PDL 0.05–0.08, PEW 0.12–
0.15, LF1 0.20–0.24, LF2 0.12–0.15, LF3
0.14–0.18, WF1 0.07–0.10, FL 0.95–1.30,
FW 0.15–0.22, MW 1.35–1.62, DLM
2.28–2.80, PRH 0.80–1.10, PL 0.55–
0.65, PND 0.50–0.60, PH 0.43–0.63,
PPL 0.25–0.34, DPW 0.50–0.74, PPW
0.54–0.79, PHB 0.20–0.29, N=10.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.47 mm, width 0.54 mm) (Figs.
165, 169). Cranium slightly wider than
long. Antenna with 2 or 3 sensilla, each
bearing spinule (Figs. 165, 169). Oc-
cipital setal row with 6–8 setae, median
pair simple (Fig. 171) otherwise bifid,
base 0.5–0.66X total length of seta,
0.06–0.10 mm long (Figs. 165, 169).
First setal row on vertex with 2 dentic-
ulate to simple setae, 0.10–0.11 mm
long. Second setal row on vertex with 4
simple setae, 0.10–0.13 mm long (Figs.
165, 169), rarely denticulate. Setae
ventral to antenna level simple, 0.12–
0.16 mm long (Figs. 165, 169). Clypeus
with transverse row of 4 setae, inner
setae shorter than outer setae, 0.10–0.11
mm long (Figs. 165, 169). Labrum
small, short (breadth 2X length). La-
brum with 4–6 sensilla and 2 setae on
dorsal surface of each half. Apex with
4–6 sensilla on each half. Each half of
epipharynx with 2–3 isolated sensilla.
Straight medial portion of mandible with
2–5 teeth that decrease in size dorsally
(Fig. 168). Maxilla with apex conical,
palpus peg-like with 5 sensilla, 1 bears
spinule. Galea conical with 2 apical
sensilla bearing spinules. Labium with
patch of spinules dorsal to each palpus,
spinules in rows of 2–3. Labial palpus
slightly elevated with 5 sensilla, each
bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Body setae of 2 types.
Simple setae (0.06–0.12 mm long) ar-
ranged in transverse row of 6–10 on ven-
tral surface of each thoracic somite and on
each of 3 anterior abdominal somites,
some with short denticulate tips. Bifid se-
tae (0.09–0.14 mm long) occur elsewhere,
base 0.66X length (Fig. 166). Bifid setae
on thoracic dorsum with shorter bases.
VOLUME 120, NUMBER 2 349
Length. 3.4–3.5 mm.
Material examined.—Various speci-
mens (FSCA). Also, see Appendix A.
Distribution.—Solenopsis macdon-
aghi is found throughout the floodplains
of eastern Argentina and western Ur-
uguay (Fig. 202). Several records exist
for Paraguay. Trager (1991) reports a
population at Cochabamba, Bolivia but
this is far removed from the known range
of S. macdonaghi and, in fact, may rep-
resent an introduction.
Comments.—Superficially, the lighter
gynes of S. macdonaghi look most similar
to S. interrupta and S. metallica in color-
ation. However, the coloration does differ
by being a somewhat duller yellow orange
in S. macdonaghi. Also, the S. macdon-
aghi gynes lack the large piligerous fo-
veolae on the head and mesosoma, along
with interfoveolar striae, which are char-
acters present in S. interrupta and S. met-
allica. The gynes of these three species
also differ slightly to greatly in sculpturing
of the postpetiole and can be normally
distinguished by this character.
Trager (1991) reported that the heads
of S. macdonaghi gynes are typically
broader than other species, but this obser-
vation was based on a limited number of
specimens. Additional measurements have
shown this not to be the case (Table 5).
The males of S. macdonaghi closely
resemble other species, but they, along
with S. saevissima, are among the largest
males. The males of S. macdonaghi look
most similar to S. quinquecuspis in size,
shape and coloration. Although males of
S. macdonaghi are normally less coarsely
sculptured than S. quinquecuspis, the
males of these two species are not easily
distinguished. Males of S. macdonaghi
are also very similar to S. megergates, but
the CI for males of S. macdonaghi is
somewhat smaller than for S. megergates.
The larva of S. macdonaghi is distinct
from that of S. saevissima in that it has
bifid setae on the head capsule. The larva
of S. macdonaghi is virtually in-
distinguishable from that of S. me-
gergates and S. quinquecuspis, despite
the smaller body size and the longer base
of the body setae in S. macdonaghi.
Solenopsis megergates Trager
(Figs. 27, 28, 62, 63, 78, 79, 98, 99, 138,
139, 170–175)
Solenopsis megergates Trager 1991:
181–182. [Holotype worker. BRAZIL.
Parana´ State. 4 km North of Curitiba.
Trager. MZSP.]
Worker.—Head broad, cordate (Fig.
139). Head sculpture with small pilig-
erous foveolae, approximately 0.01 mm
in diameter. Median frontal streak absent
or faint. Median ocellus in largest major
workers present (absent in Fig. 139).
Mandibular costulae usually present
throughout, sometimes obsolescent. Meso-
notum with 20–25 setae (Fig. 138). Meso-
notum weakly convex, in lateral view (Fig.
138). Promesonotal suture in largest major
workers angulate, sometimes projecting
upward (Fig. 138). Propodeum sculpture
glabrous posteroventral to spiracle (Fig.
138). In largest major workers, propodeum
curves directly to flattened posterior portion
(Fig. 138). Postpetiole shape much broader
than high. Postpetiole in posterior view
transversely rugose on lower 0.50–0.75,
weakly granulate, sculpture not extending to
dorsum. Color red brown on head, meso-
soma, legs and T1 maculation. Color dark
brown on metasoma excluding maculation.
Gyne.—Head. Slightly broader than
long, quadrate, sides of head convex
from eyes to occipital angles, straight to
nearly straight ventral to eyes (Fig. 28).
Eye sometimes with 3–4 setae pro-
truding from between ommatidia, length
most setae <3X length of ommatidium,
sometimes setae longer, ;4X length of
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON350
ommatidium. Ocelli large, prominent
(Fig. 28). Median ocellus circular, lateral
ocelli slightly ovate (Fig. 28). Clypeus
projecting, carinal teeth stout and sharp,
carinae well defined, less so dorsally,
slightly divergent ventrally (Fig. 28).
Paracarinal teeth small, sometimes
poorly defined (Fig. 28). Median clypeal
tooth well developed, infrequently in-
distinct (Fig. 28). Approximately 0.50 of
eye dorsal to midpoint of head (Fig. 28).
Mesosoma. Parapsidal lines present
on posterior 0.50 of disk (Fig. 27).
Mesonotum with indistinct, poster-
omedian furrow. Wing venation as in
Fig. 98.
Metasoma. Lateral faces of postpetiole
straight to weakly concave. Petiolar and
postpetiolar spiracles tuberculate in some
cases.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae moderate, width
0.005–0.03 mm in diameter, larger on
head than on thorax and abdomen. Pu-
bescence simple, golden and erect, lon-
ger and denser on head than elsewhere,
longest on anterior edge of clypeus.
Mesosoma with longest pubescence
(length >0.30 mm) 2X longer than
shortest pubescence (Fig. 27). Some-
times fine striae present between ocelli.
Mandible with 5–7 coarse, distinct cos-
tulae present, sometimes obsolescent
medially. Propodeum with fine striae
posteriorly, anterior 0.25 polished (Fig.
27). Petiolar nodes with lower 0.50 of
posterior surface finely striate to granu-
late, dorsum polished. Postpetiole with 12–
16 striations, dorsum finely granulate to
polished. Remaining integument smooth
and polished. Color varies from red brown
to brown orange. Ocellar triangle some-
times darkly pigmented. Legs usually red
brown, sometimes becoming lighter than
body (yellow brown). Mesonotal macu-
lations present anteromedially and para-
psidal lines, usually black to dark brown,
sometimes only slightly discernable from
surrounding integument. Integument along
internal margins of ocelli usually brown.
Median frontal streak absent, sometimes
area is slightly darker than surrounding
integument.
Morphometric Measurements. L
;7.4–8.9, HW 1.35–1.68, VW 0.90–
1.02, HL 1.22–1.42, EL 0.40–0.48, OD
0.14–0.20, OOD 0.20–0.28, LOW 0.10–
0.12, MOW 0.10–0.12, CD 0.16–0.26,
MFC 0.16–0.28, EW 0.30–0.42, SL
0.95–1.15, PDL 0.21–0.25, LF1 0.10–
0.14, LF2 0.08–0.11, LF3 0.07–0.11,
WF1 0.05–0.08, FL 1.15–1.32, FW
0.25–0.30, MW 1.46–1.54, DLM 2.51–
2.82, PRH 0.90–1.25, PL 0.71–0.79,
PND 0.55–0.68, PH 0.65–0.75, PPL
0.30–0.41, DPW 0.56–0.68, PPW 0.74–
0.79, PHB 0.38–0.45, N=6.
Male.—Head. Eye normally with 3–4
setae protruding from between ommatidia,
setal length £3X width of ommatidium.
Ocelli moderate to small, elliptical
(Fig. 63).
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally.
Metapleuron not broad, ;0.33 as wide
as high (Fig. 62). Wing venation as in
Fig. 99.
Metasoma. In anterior view, dorsum of
node with deep median impression, bi-
lobate. Petiolar and postpetiolar spiracles
distinctly tuberculate to not tuberculate.
Genitalia as in Figs. 78 and 79.
Coloration, Sculpturing, and Pilosity.
Pubescence short, thin, yellow, erect to
suberect and of uniform length over
body (0.25–0.30 mm), longest on gena
and vertex. Mesonotal pubescence dense
(as in Fig. 73). Propodeum with base
striato-granulate (Fig. 62). Area between
eye and insertion of antenna (Fig. 63),
posterior portion of metapleuron, and
VOLUME 120, NUMBER 2 351
base of petiolar node granulate. Some-
times, base of petiolar node rugose to
striato-granulate. Area between ocelli
(Fig. 63) and gena striato-granulate. Vertex
granulate (Fig. 63). Areas anterolateral to
median ocellus usually glabrous (Fig. 63).
Lower 0.25 of postpetiole finely striato-
granulate to granulate, remaining surface
granulate. Lateral faces of scutellum gla-
brous (Fig. 62). Remaining integument
smooth and polished. Color red brown to
brown, antennae and legs brown yellow.
Mandibles yellow to yellow brown.
Morphometric Measurements. L
;5.0–6.7, HW 0.97–1.10, VW 0.30–
0.38, HL 0.66–0.80, EL 0.40–0.49, OD
0.06–0.09, OOD 0.12–0.18, LOW 0.09–
0.12, MOW 0.10–0.15, CD 0.15–0.18,
MFC 0.13–0.16, EW 0.30–0.38, SL
0.16–0.18, SW 0.09–0.10, PDL 0.05–
0.06, PEW 0.10–0.15, LF1 0.14–0.21,
LF2 0.10–0.15, LF3 0.13–0.16, WF1
0.06–0.09, FL 1.04–1.11, FW 0.16–0.21,
MW 1.40–1.54, DLM 2.35–2.44, PRH
0.81–1.05, PL 0.61–0.66, PND 0.56–
0.61, PH 0.46–0.54, PPL 0.22–0.31,
DPW 0.56–0.63, PPW 0.65–0.69, PHB
0.21–0.28, N=8.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.46 mm, width 0.50 mm) (Figs.
170, 173). Cranium slightly broader than
long (Figs. 170, 173). Antenna with 2 or
3 sensilla, each bearing spinule (Figs. 170,
171, 173). Occipital setal row with 4–6
setae (0.06–0.08 mm long) (Figs. 170,
173); inner and outer setae simple to
denticulate, otherwise bifid, base ;0.75
length of seta (Figs. 170, 173, 174). First
setal row on vertex with 2 simple to
denticulate setae, 0.07–0.08 mm long
(Figs. 170, 173, 174). Second setal row
on vertex with 4 simple setae, 0.09–0.13
mm long (Figs. 170, 173, 174). Setae
ventral to antenna level simple, 0.08–
0.14 mm long (Figs. 170, 173, 174).
Clypeus with transverse row of 4 setae,
inner setae shorter than outer setae,
0.06–0.10 mm long (Figs. 170, 173,
174). Labrum small, short (breadth;2X
length). Labrum with 4 sensilla and 2
setae on dorsal surface of each half and
apex with 6 sensilla on each half. Each
half of epipharynx with 3–5 isolated.
Straight medial portion of mandible with
2–5 teeth that decrease in size dorsally
(Fig. 172). Maxilla with apex conical,
palpus peg-like with 5 sensilla, each
bearing one spinule. Galea conical with
2 apical sensilla, each bearing one spi-
nule. Labium with patch of spinules
dorsal to palpus, in short rows of 2–3.
Labial palpus slightly elevated with 5
sensilla, each bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Integument with fine
rugae throughout. Body setae of 2 types
(Fig. 175). Simple setae (0.04–0.14 mm
long) arranged in transverse row of 6–10
on ventral surface of each thoracic so-
mite and on each of 3 anterior abdominal
somites, some with short denticulate
tips. Bifid setae (0.06–0.11 mm long)
occur elsewhere, base ;0.5X length
(Figs. 174, 175), some with bases
;0.75X (0.08–0.10 mm long) on tho-
racic dorsum posterior to head capsule.
Length. 3.7–3.8 mm.
Material examined.—Various speci-
mens (FSCA). Also, see Appendix A.
Distribution.—The type specimens
were unavailable for study. The type
series locality is Curitiba, Parana´, Brazil
(Trager 1991). Solenopsis megergates is
currently known only from the three
southern Brazilian states of Parana´,
Santa Catarina, and Rio Grande do Sul
(Fig. 202).
Comments.—Gynes and workers of
S. megergates are similar in coloration.
The workers of this species are the
largest of any of the fire ants. The gynes,
along with those of S. macdonaghi and
S. saevissima, are the largest gynes in
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON352
this group. The darker-colored gynes of
S. megergates could be confused with S.
invicta, but the CI and OI of S. me-
gergates are normally larger than those
of S. invicta. In many cases, the sculp-
ture of the mandible and postpetiole for
workers can help separate S. megergates
from similar species.
The males of S. megergates are dis-
tinct from all other species by lacking
sculpture on the lateral faces of the
scutellum; the males of the other species
have weakly to strongly striate lateral
faces. Also, the males of S. megergates
usually have smaller ocelli than their
closest relatives (Pitts et al. 2005), S.
macdonaghi and S. quinquecuspis.
The larvae of S. megergates are dis-
tinct from the S. saevissima type by
having simple setae on the head capsule.
The larvae are virtually identical to
S. macdonaghi and S. quinquecuspis.
The S. megergates larvae have bifid setae
on the body that differ slightly from
S. macdonaghi and S. quinquecuspis by
having a slightly longer base.
Solenopsis pusillignis Trager
(Figs. 29, 30, 45, 64, 65, 80, 87, 88, 140,
141, 190–194)
Solenopsis pusillignis Trager 1991: 194.
[Holotype worker. BRAZIL. Mato
Grosso State. Cuiaba´. Trager. MZSP.]
Worker.—Head subovate to cordate
(Fig. 141). Head sculpture with small
piligerous foveolae, <0.01 mm in di-
ameter. Median frontal streak absent.
Median ocellus in largest major workers
absent. Mandibular costulae well de-
veloped throughout entire length at least
medially. Mesonotum with 20–25 setae
(Fig. 140). Promesonotal suture in largest
major workers gently curved medially,
never projecting upward (Fig. 140). Pro-
podeum sculpture granulate posteroventral
to spiracle (Fig. 140). Postpetiole shape as
high as or higher than broad. Postpetiole
sculpture in posterior view with lower 0.75
transversely rugose, granulate, weakly
granulate to glabrous and shiny. Color
generally brown yellow to darker yellow
brown with brown gaster.
Gyne.—Head. Slightly broader than
long, quadrate, sides of head convex
from eyes to occipital angles, straight
anterior to eyes (Fig. 30). Eye sometimes
with 6–10 long setae protruding from
between ommatidia, setal length >4X
length of ommatidia. Ocelli large, prom-
inent (Fig. 30). Median ocellus circular,
lateral ocelli slightly ovate (Fig. 30).
Ocelli placed in more anterior position on
head (Fig. 30). Clypeus projecting, cari-
nal teeth stout and sharp, carinae well
defined, prominent between antennal
scrobes, slightly divergent ventrally, edge
of clypeus between carinae with shallow
concave depression, depression deepest
between carinal teeth (Fig. 30). Para-
carinal teeth small, well defined (Fig. 30).
Median clypeal tooth well developed
(Fig. 30). Approximately 0.50 of eye
dorsal to midpoint of head (Fig. 30).
Mesosoma. Parapsidal lines present
on posterior 0.50 of disk (Fig. 29).
Mesonotum with median furrow on
posterior 0.25. Metasternum with bi-
dentate median process. Wing venation
as in Fig. 87.
Metasoma. Lateral faces of post-
petiole weakly to strongly concave. In
lateral view, petiolar node obtusely tri-
angular, profile of peduncle flattened an-
teriorly, convex posteriorly. Postpetiole
evenly convex. Postpetiolar spiracles
weakly tuberculate.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae small, sparse, width
<0.01 mm in diameter, larger on head
than on thorax and abdomen. Pubes-
cence simple, golden and erect, longer
and denser on head than elsewhere,
VOLUME 120, NUMBER 2 353
longest on anterior edge of clypeus.
Mesonotum pubescence 0.06–0.25 mm,
longest pubescence on mesonotum 3–4X
longer than shortest pubescence (Fig.
29). Mandible with 9–11 fine, distinct
costulae present throughout. Propodeum
with fine striae throughout (Fig. 29).
Petiolar node basal 0.75 with striato-
granulate, dorsum polished. Posterior
face of postpetiolar node with lower
0.50–0.75 finely striate, lower 0.75
granulate, dorsum polished (Fig. 45).
Remaining integument smooth and pol-
ished. Color generally orange with
mandibles and antennae orange brown,
apical and lateral margins of metasoma
segments 3–6 brown, and internal mar-
gins of ocelli dark brown.
Morphometric Measurements. L
;6.6, HW 1.20, VW 0.80, HL 1.14, EL
0.29, OD 0.12, OOD 0.16, LOW 0.11,
MOW 0.13, CD 0.13, MFC 0.16, EW
0.28, SL 0.83, PDL 0.17, LF1 0.09, LF2
0.07, LF3 0.08, WF1 0.06, FL 0.96, FW
0.23, MW 1.25, DLM 2.20, PRH 0.43,
PL 0.61, PND 0.51, PH 0.60, PPL 0.34,
DPW 0.50, PPW 0.62, PHB 0.36, N=1.
Male.—Head. Eye normally with 3–4
setae protruding from between omma-
tidia, setal length £3X width of omma-
tidium. Ocelli very large and prominent,
elliptical (Fig. 65).
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally.
Metapleuron not broad, ;0.50 as wide
as high (Fig. 64). Wing venation as in
Fig. 88.
Metasoma. In cephalic view, dorsum
of node with shallow median impression,
weakly bilobate. Petiolar and postpetiolar
spiracles distinctly tuberculate to not tu-
berculate. Genitalia as in Fig. 80.
Coloration, Sculpturing, and Pilosity.
Pubescence short (0.15–0.20 mm),
dense, yellow, erect to suberect and of
uniform length over mesonotum, longest
on gena and vertex. Mesonotal pubes-
cence sparse (as in Fig. 72). Propodeum
striato-granulate, medially finely granu-
late (Fig. 64). Lateral faces of scutellum
striato-granulate (Fig. 64). Surface
granulate in area between eye and in-
sertion of antenna (Fig. 65), posterior
portion of metapleuron, and base of
petiolar node. Posterior surface of post-
petiolar node with lower 0.25 finely
striato-granulate, sometimes with lower
0.50 finely striato-granulate but glabrous
medially, dorsum polished. Area be-
tween ocelli rugose to granulate (Fig.
65). Vertex glabrous posterior to ocelli.
Several striae present anterior to occipi-
tal carina. Area posterior to eyes and
antennal scrobes weakly granulate. Re-
maining integument smooth and pol-
ished. Head and gaster red brown.
Clypeus, mandibles, petiole and post-
petiole lighter yellow. Antennae and legs
yellow. Mesosoma yellow to brown with
median longitudinal stripe, area around
parapsidal lines and scutellum red
brown. Sometimes mesosoma yellow
and parapsidal lines only slightly darker
than surround integument.
Morphometric Measurements. L
;4.9–5.4, HW 0.95–1.0, VW 0.35–0.42,
HL 0.74–0.80, EL 0.44–0.48, OD 0.10–
0.14, OOD 0.10–0.13, LOW 0.16–0.17,
MOW 0.16–0.19, CD 0.10–0.12, MFC
0.33–0.36, EW 0.3–0.40, SL 0.14–0.18,
SW 0.07–0.10, PDL 0.05–0.08, PEW
0.10–0.12, LF1 0.17–0.19, LF2 0.13–
0.15, LF3 0.13–0.14, WF1 0.09–0.10,
FL 0.98–1.05, FW 0.15–0.19, MW 1.20–
1.30, DLM 2.15–2.30, PRH 0.80–0.88,
PL 0.65–0.66, PND 0.58–0.61, PH 0.40–
0.42, PPL 0.26–0.30, DPW 0.49–0.55,
PPW 0.55–0.64, PHB 0.14–0.16, N=8.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.44 mm, length 0.44 mm) (Figs.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON354
190, 193). Cranium as broad as long
(Figs. 190, 193). Antenna with 2 or 3
sensilla, each bears spinule (Figs. 190,
193). Occipital setal row with 10–12
bifid setae (less often 8), base ;0.3–
0.5X total length of seta (Fig. 191), setae
0.05–0.10 mm long (Figs. 190, 193,
194). First setal row on vertex with 2
bifid setae, base ;0.5X total length of
seta, ;0.07 mm long (Figs. 190, 193,
194). Second setal row on vertex with 4
setae, inner 2 setae simple to denticulate,
outer 2 setae bifid (base ;0.5X length),
0.08–0.11 mm long (Figs. 190, 193,
194). Setae ventral to antenna level
simple, 0.08–0.18 mm long (Figs. 190,
193, 194). Clypeus with transverse row
of 4 setae, inner setae shorter than outer
setae, 0.08–0.11 mm long. Labrum
small, short (breadth 2.4X length). La-
brum with 5 minute sensilla and 2 setae
on anterior surface of each half and
ventral border with 4–6 sensilla on each
half. Each half of posterior surface of
labrum with 3–4 isolated and 2 contig-
uous sensilla. Straight medial portion of
mandible with 2–5 teeth that decrease in
size dorsally (Fig. 192). Maxilla with
apex conical, palpus peg-like with 5
sensilla, 1 bears spinule. Galea conical,
smaller than maxillary palpus, with 2
apical sensilla, each bearing one spinule.
Labium with patch of spinules dorsal to
each palpus, spinules coarse and isolated
or in short rows of 2–3. Labial palpus
slightly elevated with 5 sensilla, each
bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Body setae of 2 types.
Simple setae (0.06–0.10 mm long) ar-
ranged in transverse row of 4–5 on
ventral surface of each thoracic somite
and on each of 3 anterior abdominal
somites, some with short denticulate
tips. Bifid setae (0.05–0.09 mm long)
occur elsewhere, base varying between
0.2–0.5X length.
Length. 2.6–2.7 mm.
Material examined.—See Appendix A.
(Holotype was unavailable for study.)
Distribution.—Currently, S. pusillignis
is known from the type locality and the
vicinity of Corumba´, Mato Grosso do
Sul, Brazil (Fig. 203).
Variation.—Trager (1991) considered
this to be a small species, but also re-
ported measurements from one series of
specimens that he thought were atypi-
cally large. All of the newly collected
colonies reported here have larger
workers that fall into the atypical ranges
noted in parenthesis by Trager (1991).
Thus, this species is larger than first
thought. In addition, some of the major
workers have their heads deeply emar-
ginate posteriorly (Fig. 141), a distinc-
tive feature that was not mentioned
previously.
Comments.—The gynes and workers
of S. pusillignis superficially look like
small S. macdonaghi. This species is
easily distinguished from S. macdonaghi
and others, however, by having yellow
workers with the posterodorsal and
posteroventral area of the propodeal
spiracle granulate, and by having the
heads of the largest workers deeply
emarginate (Fig. 141). This species also
has small gynes with small OOI mea-
surements and large OI measurements
and light-colored males with mesonotal
maculae. The gynes of S. pusillignis
differ from S. electra in coloration of the
gaster (S. pusillignis has a lighter gaster
and has a weakly developed T1 macu-
lation), and S. pusillignis has a less de-
veloped median clypeal tooth.
The males of S. pusillignis normally
have relatively large ocelli. This sug-
gests that they may be nocturnally
active.
The larvae of this species are also
distinct in having more setae on the head
capsule (10–12) than other species
VOLUME 120, NUMBER 2 355
(normally 8 or less). Also, some have
denticulate setae on the body, which
differ from those found in some S. sae-
vissima by being denticulate only at the
extreme apex.
Solenopsis pythia Santschi
(Figs. 31, 32, 46, 51, 53)
Solenopsis pythia Santschi 1934: 30.
[Holotype gyne. ARGENTINA. Mis-
iones Province. Lorento. A. A. Oglobin.
NHMB.]
S. (Solenopsis) pythia Wilson 1952: 61.
Worker.—Head weakly ovate to sub-
quadrate. Head sculpture with small pilig-
erous foveolae, approximately 0.01 mm in
diameter. Median frontal streak absent.
Median ocellus absent in largest major
workers. Mandibular costulae present
throughout. Mesonotum with 20–25 se-
tae. Promesonotal suture in largest major
workers gently curved medially. Meso-
notum weakly convex in lateral view.
Propodeum sculpture glabrous poster-
oventral to spiracle. Postpetiole shape as
high as or higher than broad. Postpetiole
sculpture in posterior view with lower
0.33–0.50 transversely rugose, upper
surface glabrous and shiny. Color gener-
ally orange brown, with frons, clypeus
and venter yellow brown.
Gyne.—Head. Slightly broader than
long, quadrate, sides of head convex
from eyes to occipital angles, straight to
nearly straight ventral to eyes (Fig. 32).
Eye normally with 2–4 several short se-
tae protruding from between ommatidia,
setal length £3X width of ommatidium.
Ocelli large, prominent (Fig. 32). Me-
dian ocellus circular, lateral ocelli
slightly ovate (Fig. 32). Clypeus pro-
jecting, carinal teeth stout and sharp,
carinae weakly to moderately defined,
less so dorsally, slightly divergent ven-
trally (Fig. 32). Paracarinal teeth usually
absent, or more rarely poorly defined
(Fig. 32). Median clypeal tooth poorly
developed, usually absent (Fig. 32).
Approximately 0.50 of eye dorsal to mid-
point of head (Fig. 32). Antenna usually
11-segmented, sometimes 10-segmented.
Mesosoma. Parapsidal lines present
on posterior half of disk (Fig. 31).
Mesonotum with distinct, median furrow
on posterior 0.50 to 0.33 on disk. Pos-
terior margin of mesonotum angulate
medially, bent anteriorly. Posterior mar-
gin of scutellum sometimes angulate
medially. Metasternum lacking median
bidentate process. Wings not examined.
Metasoma. Lateral faces of post-
petiole strongly to slightly concave.
Petiolar spiracle weakly tuberculate.
Postpetiolar spiracle not tuberculate.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae large, conspicuous,
width 0.010–0.020 mm in diameter
(Fig. 32), slightly larger on head than on
thorax and abdomen (Fig. 32). Dorsum
of mesosoma with distinctly piligerous
foveolae (Fig. 51). Pubescence simple,
golden and erect, of uniform length
(0.15–0.20 mm) (Fig. 53), longer and
denser on head than elsewhere, longest
on anterior edge of clypeus. Mandible
with several coarse, distinct costulae
present throughout. Propodeum and
petiole postpetiole striato-rugulose
throughout (Fig. 31). Postpetiole striato-
rugulose throughout, sometimes extreme
dorsum glabrous (Fig. 46). In some ca-
ses, sculpture of postpetiole tuberculate
and dorsum finely granulate. Inter-
foveolar spaces of head and pronotum
finely striate; striae distinct to indis-
tinct (Fig. 32). Remaining interfoveolar
spaces smooth and polished. Color yel-
low orange with medial area of meso-
notum, parapsidal lines, lateral margins
of T1 and preapical transverse areas on
gaster segments brown (Fig. 53). Internal
margins of ocelli sometimes brown.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON356
Morphometric Measurements. L;5.3–
6.2, HW 1.3, VW 0.7–0.8, HL 1.0–1.1,
EL 0.4–0.5, OD 0.1–0.15, OOD 0.15–
0.25, LOW 0.08–0.12, MOW 0.10–0.12,
CD 0.14–0.16, MFC 0.15–0.18, EW
0.35–0.40, SL 0.69–0.82, PDL 0.16–
0.18, LF1 0.1, LF2 0.1, LF3 0.1, WF1
0.06–0.07, FL 0.91–1.02, FW 0.19–0.25,
MW 1.18–1.32, DLM 2.28–2.44, PRH
0.90–1.03, PL 0.72–0.83, PND 0.61–
0.73, PH 0.62–0.72, PPL 0.32–0.43,
DPW 0.49–0.84, PPW 0.48–0.61, PHB
0.58–0.71, N=7.
Male.—Unknown.
Fourth instar worker larva.—Unknown.
Material examined.—Specimens ex-
amined were from Campo Grande, Mato
Grosso do Sul, Brazil, Boctucatua, Sa˜o
Paulo State, Brazil (FSCA), and Posadas,
Misiones Province, Argentina (JPPC,
SDPC).
Distribution.—Currently, this species
is known from the material listed above
and the type locality of Loreto, Misiones
Province, Argentina (Fig. 202).
Comments.—The major workers of
S. pythia look like small workers of
S. saevissima. The gynes, however, are
easily recognized by having acute oc-
cipital angles, large piligerous foveolae
of the head and mesosoma, coarse cos-
tulae on the mandibles, a small OI,
a distinct median furrow on the posterior
0.33 to 0.50 of the mesonotum, and a
thick coarsely sculptured petiolar node.
Trager (1991) lists piligerous foveolae
size as 0.01–0.15 mm: this must be
a misprint and should read “0.010–
0.015 mm.” The petiolar node is
shorter and subquadrate and the pos-
terior angles of propodeum are more
defined than in S. saevissima. This is
the only species in the S. saevissima
species-group that lacks the bidentate
metasternal process.
Solenopsis pythia has been suggested
by some (e.g., Trager 1991) to be so
unique that it is suspected to be a social
parasite. Many of the gyne characters
may actually be sympleisomorphic, as
they are shared with the gynes in the
S. molesta species-group. These charac-
ters include a quadrate first flagellomere,
large and conspicuous piligerous foveo-
lae on the head and mesosoma, coarse
costulae of the mandibles, thick and
coarsely sculptured petiolar node, short
and subquadrate petiolar node, well de-
marcated posterior angles of propo-
deum, and absent bidentate process of
the metasternum. There are obvious
synapomorphic S. saevissima species-
group characters in S. pythia, however,
such as the lack of a ventral petiolar
process in gynes and workers.
Several dealated (wingless) gynes were
collected from a single nest, suggesting
that polygyny may occur in this species.
Solenopsis quinquecuspis Forel
(Figs. 33, 34, 43, 55, 66, 67, 81, 100, 101,
142, 143, 176, 178–181)
Solenopsis pylades var. quinquecuspis
Forel 1913: 224. [Syntype workers.
ARGENTINA. Buenos Aires Province.
Bahia Blanca. 28-X-913 (=1913).
Zelenko. NHMB.]
S. geminata saevissima var. quinque-
cuspis: Wheeler 1915: 397.
S. saevissima var. quinquecuspis: Santschi
1916: 381.
S. (Solenopsis) saevissima quinquecuspis:
Creighton 1930: 86.
S. blumi Buren 1972: 20. [NMNH.]
Worker.—Head broad, cordate (Fig.
143). Head sculpture with small pilig-
erous foveolae, approximately 0.01 mm
in diameter. Median frontal streak pres-
ent, sometimes indistinct. Median ocel-
lus in largest major workers present
(absent in Fig. 143). Mandibular costulae
present throughout, sometimes obsolescent.
VOLUME 120, NUMBER 2 357
Mesonotum with 20–25 setae. Prom-
esonotal suture in largest major workers
angulate medially, sometimes projecting
upward. Mesonotum in lateral view
weakly convex (Fig. 142). Propodeum
sculpture glabrous posteroventral to spi-
racle (Fig. 142). Propodeum in largest
major workers curves upward from met-
anotal groove higher than flattened pos-
terior portion, appearing as anterior raised
portion in lateral view. Postpetiole shape
much broader than high. Postpetiole in
posterior view with at least 0.75 trans-
versely rugose to punctate-rugose, ru-
gosity sometimes extending to dorsum.
Color generally brown to dark brown on
head, mesosoma, and median area of
petiole. Gaster dark brown. Frons, clyp-
eus, and T1 maculation brown orange.
Gyne.—Head. Slightly broader than
long, quadrate, sides of head convex from
eyes to occipital angles, straight to nearly
straight ventral to eyes (Fig. 34). Eye
sometimes with 3–12 setae protruding
from between ommatidia, most setae £3X
length of ommatidium, sometimes one or
two £4X length of ommatidium. Median
ocellus moderate, circular (Fig. 34). Lat-
eral ocelli slightly ovate, small to moder-
ate (Fig. 34). Clypeus projecting, carinal
teeth stout and sharp, carinae indistinct
between scrobes, slightly divergent ven-
trally (Fig. 34). Paracarinal teeth small,
usually well defined (Fig. 34). Median
clypeal tooth well developed (Fig. 34).
Approximately 0.50 of eye dorsal to
midpoint of head (Fig. 34).
Mesosoma. Parapsidal lines present
on posterior 0.50 of disk (Fig. 33).
Mesonotum without posteromedian
furrow. Bidentate medial process pres-
ent on metasternum. Wing venation as
in Fig. 100.
Metasoma. Lateral faces of postpetiole
weakly concave to weakly convex. Petio-
lar and postpetiolar spiracles slightly tu-
berculate in some cases.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae small, sparse, width
<0.01 mm in diameter, larger on head
than on thorax and abdomen. Pubes-
cence simple, pale brown to yellow and
erect, longer and denser on head than
elsewhere, longest on anterior edge of
clypeus. Mesosoma with longest pubes-
cence (length >0.30 mm) 2X longer than
shortest pubescence (Fig. 33). Mandible
with 10–12 fine costulae. Propodeum
with fine striae throughout (Figs. 33, 55).
Posterior face of petiolar nodes with
0.75 of lower surface finely striato-
granulate. Often, median striae of post-
petiole obsolescent laterally; normally
11–13 striae present (Fig. 43). Dorsum
glabrous. Remaining integument smooth
and polished. Color generally red brown.
Venter of head, frons and coxae orange
yellow. Gaster dark brown, sometimes
orange anteriorly. T1 and S1 orange on
basal 0.50 of disk, blending to red brown
apically. Dark brown maculations pres-
ent on mesonotum both anteromedially
and on parapsidal lines (as in Fig. 52).
Median longitudinal maculation some-
times reaches scutellum. Internal mar-
gins of ocelli not brown. Median frontal
streak present (as in Fig. 50).
Morphometric Measurements. L
;7.1–7.7, HW 1.40–1.45, VW 0.81–
0.95, HL 1.24–1.36, EL 0.40–0.44, OD
0.13–0.16, OOD 0.15–0.20, LOW 0.11–
0.16, MOW 0.09–0.13, CD 0.17–0.20,
MFC 0.15–0.23, EW 0.30–0.34, SL
0.94–1.01, PDL 0.17–0.19, LF1 0.08–
0.11, LF2 0.07–0.10, LF3 0.06–0.09,
WF1 0.06–0.07, FL 1.10–1.20, FW
0.26–0.31, MW 1.26–1.33, DLM 2.50–
2.70, PRH 1.00–1.05, PL 0.65–0.72,
PND 0.56–0.61, PH 0.66–0.75, PPL
0.25–0.34, DPW 0.50–0.71, PPW 0.60–
0.74, PHB 0.36–0.44, N=7.
Male.—Head. Eye normally with 2–8
setae protruding from between ommatidia,
setae length £3X length of ommatidium.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON358
Ocelli large and prominent, elliptical
(Fig. 67).
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally.
Metapleuron broad, ;0.66 as wide as
high (Fig. 66). Wing venation as in
Fig. 101.
Metasoma. In cephalic view, dorsum
of node with deep median impression,
bilobate, sometimes lobes curve poste-
riorly. Petiolar spiracle distinctly tuber-
culate to not tuberculate. Postpetiolar
spiracle distinctly tuberculate. Genitalia
as in Fig. 81.
Coloration, Sculpturing, and Pilosity.
Pubescence short, yellow, erect to sub-
erect (0.25–0.30 mm in length) on mes-
onotum. Mesonotal pubescence dense
(as in Fig. 73). Some shorter pubescence
(0.15 mm in length) also on mesonotum.
Pubescence longest on gena and vertex.
Propodeum with base striato-granulate,
medially coarsely granulate (Fig. 66).
Integument coarsely granulate on area
between eye and insertion of antenna,
area between ocelli, margins of meta-
pleuron, and base of petiolar node
(Figs. 66, 67). Vertex and, sometimes,
gena striato-granulate. Head usually
glabrous and shiny anteroventral to lat-
eral ocelli. Head otherwise granulate.
Pronotum granulate posteriorly. Meso-
notum sometimes with coarsely granu-
late to striate margins. Posterior surface
of postpetiolar node coarsely granulate
throughout, sometimes rugose. Lateral
faces of scutellum striate (Fig. 66). Re-
maining integument smooth and pol-
ished. Color generally dark brown to
black, legs brown. Antennal scape, ped-
icel and first flagellum brown, distal
portion of flagellum blending to yellow
apically. Mandibles yellow brown to
brown.
Morphometric Measurements. L
;5.3–6.0, HW 1.02–1.10, VW 0.36–
0.41, HL 0.77–0.82, EL 0.46–0.50, OD
0.09–0.12, OOD 0.14–0.23, LOW 0.10–
0.14, MOW 0.11–0.14, CD 0.17–0.21,
MFC 0.10–0.15, EW 0.32–0.37, SL
0.15–0.23, SW 0.07–0.12, PDL 0.05–
0.08, PEW 0.11–0.16, LF1 0.15–0.22,
LF2 0.10–0.17, LF3 0.15–0.19, WF1
0.09–0.12, FL 1.05–1.22, FW 0.16–0.21,
MW 1.41–1.52, DLM 2.36–2.53, PRH
0.90–0.96, PL 0.64–0.67, PND 0.54–
0.60, PH 0.25–0.28, PPL 0.24–0.35,
DPW 0.50–0.62, PPW 0.61–0.70, PHB
0.20–0.28, N=8.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.49 mm, width 0.55 mm) (Figs.
176, 178). Cranium slightly broader than
long (Figs. 176, 178). Antenna with 2 or
3 sensilla, each bearing spinule (Figs.
176, 178). Occipital setal row with 6–8
simple setae, 0.09–0.13 mm long (Fig.
181); rarely some specimens with 1–2
denticulate setae (Figs. 178, 180). First
setal row on vertex with 2 simple setae,
0.09–0.11 mm long (Figs. 176, 178).
Second setal row on vertex with 4 simple
setae, 0.12–0.13 mm long (Figs. 176,
178). Setae ventral to antenna level
simple, 0.15–0.19 mm long (Figs. 176,
178). Clypeus with transverse row of 4
setae, inner setae shorter than outer se-
tae, 0.06–0.11 mm long (Figs. 176, 178).
Labrum small, short (breadth 2X length),
slightly narrowed medially (Figs. 176,
178). Labrum with 4 sensilla and 2 setae
on anterior surface of each half. Ventral
border with 4–6 sensilla on each half.
Each half of posterior surface of labrum
with 2–3 isolated sensilla. Straight medial
portion of mandible with 1–4 teeth that
decrease in size dorsally (Fig. 179).
Maxilla with apex conical, palpus peg-like
with 5 sensilla, each bearing one spinule.
Galea conical with 2 apical sensilla, each
bearing one spinule. Labium with patch of
VOLUME 120, NUMBER 2 359
spinules dorsal to each palpus, in short rows
of 2–3. Labial palpus slightly elevated with
5 sensilla, each bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Body setae of 2 types.
Simple setae (0.04–0.10 mm long) ar-
ranged in transverse row of 6–8 on
ventral surface of each thoracic somite
and on each of 3 anterior abdominal
somites, some with short denticulate
tips. Bifid setae (0.07–0.11 mm long)
occur elsewhere, base 0.5X length,
branches more or less perpendicular to
base, tips recurved. Setae on thoracic
dorsum with short base (<0.2X length).
Length. Approximately 3.8 mm.
Material examined.—Various speci-
mens (FSCA). Also, see Appendix A.
Distribution.—The current range of
S. quinquecuspis extends south from Rio
Grande do Sul, Brazil through Uruguay
and into Argentina (Fig. 202). In
Argentina, it occurs in Buenos Aires and
La Pampa Provinces and the eastern edges
of Santa Fe´ and Co´rdoba Provinces
(Fig. 202).
Comments.—The gynes of S. quin-
quecuspis are similar to the darker col-
ored gynes of S. invicta. However, the OI
of S. quinquecuspis is normally larger
than that of S. invicta.
The gynes of the darker varieties
of S. richteri could be confused for
S. quinquecuspis. In this case, the mes-
onotum of S. richteri is completely
darkened and the mesonotal maculae are
indiscernible. Also for S. richteri, the
maculation on the first segment of the
gaster covers the anterior 0.75 and it may
end abruptly posteriorly. For S. quin-
quecuspis the maculation fades out
gradually posteriorly. For S. quinque-
cuspis, this gaster maculation is only on
the anterior 0.50 or less and is never
distinctly margined posteriorly.
The male of S. quinquecuspis is dark
in coloration and is similar to most of the
other darker species. The pubescence is
longer and denser than in S. saevissima.
The S. quinquecuspis male normally is
more coarsely sculptured than S. mac-
donaghi. The gena is not granulate nor is
it as sculptured as in S. invicta.
The larvae of S. quinquecuspis are
distinct from the S. saevissima type by
having simple setae on the head capsule.
The larvae of S. quinquecuspis are sim-
ilar to S. macdonaghi and S. megergates.
Although the body of S. quinquecuspis is
larger and the setae on the body have
a shorter base compared to S. macdon-
aghi, they are virtually indistinguish-
able. These larvae are much larger than
the larvae of S. richteri (as expected
given adult worker size), and lack multi-
branched setae and rugae on the head
capsule.
Studies of nuclear and mtDNA ge-
netic markers in S. quinquecuspis sug-
gest that this species hybridizes with
S. invicta and S. richteri in an area where
the ranges of all three species overlap, in
the vicinity of Rosario, Santa Fe Province,
Argentina (Ross and Shoemaker 2005). In
other areas of the range of S. quinque-
cuspis, there is no genetic evidence for
such hybridization (Ross and Trager
1990).
Solenopsis richteri Forel
(Figs. 35, 36, 48, 68, 69, 82, 83, 102, 103,
144, 145, 185–189)
Solenopsis pylades var. richteri Forel
1909: 267. Syntype workers. [Syntype
workers, gynes, males. ARGENTINA.
Buenos Aires. Richter. MHNG.]
S. pylades var. tricuspis Forel 1912: 397.
Syntype workers.
S. geminata saevissima var. richteri:
Wheeler 1915: 397.
S. saevissima var. richteri: Santschi
1916: 281.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON360
S. saevissima var. tricuspis: Santschi
1916: 281. [NHMB?]
S. (Solenopsis) saevissima richteri:
Creighton 1930: 87.
S. saevissima var. oblongiceps Santschi
1936: 405. [NHMB]
S. saevissima richteri: Wilson 1952: 66.
S. richteri Buren 1972: 4. Worker, gyne,
male.
Worker.—Head ovate to weakly cor-
date (Fig. 145). Head sculpture with
small piligerous foveolae, <0.01 mm in
diameter. Median frontal streak absent.
Median ocellus in largest major workers
absent (Fig. 145). Mandibular costulae
present, obsolescent medially. Humerus
distinctly angulate, with distinct tu-
berculate boss. Mesonotum with 20–26
setae. Promesonotal suture curved medi-
ally, never projecting upward. Propodeum
sculpture glabrous posteroventral to spi-
racle (Fig. 144). Postpetiole shape as high
as or higher than broad. Postpetiole with
lower 0.50 or less transversely rugose to
punctate-rugose, dorsum and face dorsal
to sculpture nitid, glabrous. Color gener-
ally black with mandibles, lateral areas of
clypeus, antennal fossae, mesosomal su-
tures, and T1 maculations dark brown to
yellow brown.
Gyne.—Head. Slightly broader than
long, quadrate, sides of head convex
from eyes to occipital angles, straight to
nearly straight ventral to eyes (Fig. 36).
Eye sometimes with 3–4 setae pro-
truding from between ommatidia, setal
length £3X width of ommatidium. Me-
dian ocellus large (Fig. 36). Lateral
ocelli small to moderate (Fig. 36). Me-
dian ocellus circular, lateral ocelli
slightly ovate (Fig. 36). Clypeus pro-
jecting, carinal teeth stout and sharp,
carinae sometimes indistinct, less so dor-
sally, slightly divergent ventrally (Fig. 36).
Paracarinal teeth small, usually well de-
fined (Fig. 36). Median clypeal tooth well
developed (Fig. 36). Approximately
0.50 of eye dorsal to midpoint of head
(Fig. 36).
Mesosoma. Parapsidal lines present
on posterior 0.50 of disk (Fig. 35).
Mesonotum with indistinct, median fur-
row on posterior 0.25 or less. Bidentate
median process present on metasternum.
Wing venation as in Fig. 102.
Metasoma. Lateral faces of post-
petiole weakly to strongly concave.
Petiolar and postpetiolar spiracles tu-
berculate in some cases.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae small, sparse, width
<0.01 mm in diameter, larger on head
than on thorax and abdomen. Pubes-
cence simple, pale brown to yellow and
erect, longer and denser on head than
elsewhere, longest on anterior edge of
clypeus. Pubescence orange on T1 or-
ange integumental maculation. Meso-
soma with longest pubescence (length
>0.30 mm) 2X longer than shortest
pubescence (Fig. 35). Mandible with
several coarse, distinct costulae, obso-
lescent medially. Propodeum with fine
striae posteriorly, anterior 0.25 polished
(Fig. 35). Posterior surface of petiolar
node with 0.75 of lower surface with fine
striae, dorsum polished. Posterior sur-
face of postpetiolar node with 0.75 of
lower surface finely striate, 12–14 striae
present, median striae sometimes obso-
lescent laterally (Fig. 48), dorsum is
polished to slightly granulate. Remain-
ing integument smooth and polished.
Two color forms exist. Dark form is dark
brown except antennal scape black, fla-
gellum brown to orange, both T1 and S1
with medial orange maculation, other
sternites brown with dark brown apices,
and petiole sometimes orange with dark
brown dorsum. Maculations on T1 and S1
are well defined laterally and apically.
Light form is orange except brown on
vertex, around compound eyes, apically
VOLUME 120, NUMBER 2 361
on T1, and preapically on remaining
tergites. Both forms have dark brown
maculations anteriorly on pronotum,
anteromedian area of mesonotum, area
around parapsidal lines, sometimes on
median area of axillae, anteromedian and
triangular posteromedian area of scutel-
lum, medially on anepisternum, and me-
dially and laterally on propodeum (as in
Fig. 52). Both forms have dark brown
finger-like projections of pigment from
preapical tergal bands to apical setae. In-
ternal margins of ocelli dark brown. Me-
dian frontal streak usually absent, not
discernable from surrounding integument.
Morphometric Measurements. L
;7.5–8.5, HW 1.4–1.5, VW 1.0–1.2, HL
1.2–1.3, EL 0.3–0.5, OD 0.1–0.2, OOD
0.15–0.20, LOW 0.08–0.10, MOW
0.10–0.15, CD 0.15–0.20, MFC 0.20–
0.25, EW 0.30–0.40, SL 0.92–1.23, PDL
0.18–0.23, LF1 0.01–0.16, LF2 0.07–
0.1, LF3 0.08–0.11, WF1 0.07–0.10, FL
1.10–1.23, FW 0.21–0.32, MW 1.40–
1.55, DLM 2.46–2.73, PRH 1.00–1.12,
PL 0.72–0.91, PND 0.51–0.60, PH 0.60–
0.72, PPL 0.39–0.53, DPW 0.59–0.69,
PPW 0.59–0.71, PHB 0.28–0.51, N=10.
Male.—Head. Eye normally with 2–4
setae protruding from between ommatidia,
setal length £3X width of ommatidium.
Ocelli large and prominent, elliptical
(Fig. 69).
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally.
Metapleuron broad,;0.66 as wide as high
(Fig. 68). Wing venation as in Fig. 103.
Metasoma. In cephalic view, dorsum
of node transverse to having shallow
median impression and weakly bilobate,
sometimes lobes curve posteriorly. Petio-
lar spiracles distinctly tuberculate to not
tuberculate. Postpetiolar spiracle dis-
tinctly tuberculate to greatly tuberculate,
tubercles higher than width of base.
Genitalia as in Figs. 82 and 83.
Coloration, Sculpturing, and Pilosity.
Pubescence short, yellow, erect to sub-
erect and of uniform length over body
(0.15–0.20 mm), longest on gena and
vertex. Mesonotal pubescence dense (as
in Fig. 73). Propodeum with base striato-
granulate, medially glabrous (Fig. 68).
Integument coarsely granulate in area
between eye and insertion of antenna,
area between ocelli, pronotum, posterior
portion of metapleuron, and base of peti-
olar node (Figs. 68, 69). Gena granulate,
sometimes weakly striato-granulate. Head
otherwise granulate. Posterior surface of
postpetiolar node with lower 0.50 of sur-
face striato-granulate, remainder polished.
Metapleuron sometimes with striae both
dorsally and ventrally. Lateral faces of
scutellum striate (Fig. 68). Remaining in-
tegument smooth and polished. Color
generally red brown to black. Antennae
and legs yellow brown. Mandibles brown.
Morphometric Measurements. L
;6.1–6.5, HW 1.0–1.1, VW 0.4–0.5, HL
0.7–0.8, EL 0.4–0.5, OD 0.12–0.13,
OOD 0.1–0.2, LOW 0.10–0.12, MOW
0.10–0.15, CD 0.17–0.23, MFC 0.10–
0.15, EW 0.3–0.40, SL 0.15–0.20, SW
0.1–0.12, PDL 0.08–0.10, PEW 0.10–
0.14, LF1 0.15–0.25, LF2 0.12–0.15,
LF3 0.14–0.16, WF1 0.07–0.11, FL 1.1–
1.2, FW 0.15–0.22, MW 1.39–1.52,
DLM 2.40–2.62, PRH 0.89–1.12, PL
0.58–0.73, PND 0.51–0.60, PH 0.49–
0.61, PPL 0.20–0.30, DPW 0.61–0.70,
PPW 0.48–0.73, PHB 0.10–0.22, N=12.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.52 mm, width 0.55 mm) (Figs.
185, 189). Cranium slightly broader
than long (Figs. 185, 189). Antenna with
2 or 3 sensilla, each bearing spinule
(Figs. 185, 189). Integument of head
with fine rugae. Occipital setal row with
6–8 simple setae, 0.08–0.14 mm, rarely
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON362
some specimens with single bifid to den-
ticulate seta, base;0.8–0.95X total length
of seta (Fig. 185). First setal row on vertex
with 2 simple setae, 0.09–0.11 mm long
(Figs. 185, 189). Second setal row on
vertex with 4 simple setae, inner 2 setae
orientated farther from first setal row on
vertex, appear out of alignment with row,
0.09–0.15 mm long (Figs. 185, 189). Se-
tae ventral to antenna level simple, 0.11–
0.18 mm long (Figs. 185, 189). Clypeus
with transverse row of 4 setae, inner setae
shorter than outer setae, 0.06–0.10 mm
long (Figs. 185, 189). Labrum small, short
(breadth 2.8X length), slightly narrowed
medially. Labrum with 4 minute sensilla
and 2 setae on dorsal surface of each half
and apex with 5–7 sensilla on each half.
Each half of epipharynx with 2–3 isolated
sensilla. Straight medial portion of man-
dible with 2–5 teeth that decrease in size
dorsally (Fig. 188). Maxilla with apex
conical, palpus peg-like with 5 sensilla,
each bearing one spinule. Galea conical
with 2 apical sensilla, each bearing one
spinule. Labium with isolated patches of
spinules dorsal to each palpus. Labial
palpus slightly elevated with 5 sensilla,
each bearing one spinule.
Body. Spiracles small, first spiracle
larger than others. Body setae of 3 types.
Simple setae, slightly curved (0.08–
0.15 mm long), arranged in transverse row
of 6–12 on ventral surface of each thoracic
somite and on each of 3 anterior abdom-
inal somites. Bifid setae (0.06–0.09 mm
long) occur elsewhere, base;0.5X length.
Multibranched setae occur rarely in the
area immediately posterior to head on
thoracic dorsum (Figs. 186, 187).
Length. 2.7–3.1 mm.
Material examined.—Various speci-
mens (FSCA). Also, see Appendix A.
Distribution.—In South America, the
range of S. richteri extends from Parana´
State, Brazil south and west from Mis-
iones Province to Mendoza Province in
Argentina (Fig. 203). This species also
has been introduced into North Amer-
ica, where it is currently confined to the
northwestern corner of Alabama, the
northeastern corner of Mississippi, and
south-central Tennessee. A broad S. richteri
x invicta hybrid zone exists south and east
of the S. richteri range, including much
of Mississippi, northern Alabama, and
the northwestern corner of Georgia
(Shoemaker et al. 1996, Gardner et al.
2008, Oliver et al. 2009).
Comments.—The gynes of the lighter
varieties of S. richteri and S. interrupta
are very similar in coloration due to the
first tergite of the gaster sometimes
having an orange tergal maculation with
a distinct posterior margin. In many ca-
ses, the gynes of these two species are
difficult to differentiate. However, they
differ in the sculpturing of the postpetiole.
Also, S. richteri gynes are normally darker
in coloration and the OOI is much smaller
than in S. interrupta. The workers of
S. interrupta are larger than S. richteri and
easily separated. Gynes of S. richteri in
the United States are of the light form and
are similar to those found in the northern
range of the species in southern Brazil.
This is probably the point of origin for the
United States population.
The gynes of S. richteri from the
westernmost areas of the native range tend
to be more darkly colored than the eastern
representatives, resembling somewhat
the darker S. invicta gynes. However,
S. richteri gynes are much darker in
coloration and usually have a distinct
tergal maculation on the gaster. Also,
the lateral margins of the postpetiole
are more concave than in S. invicta.
The gynes of S. richteri have weakly
concave to straight lateral margins.
Males of S. richteri are similar in
coloration to many of the species within
the species-group. However, the OOI
of S. richteri is much smaller than in
VOLUME 120, NUMBER 2 363
S. interrupta.Also, the males of S. richteri
sometimes have a very distinct tuberculate
postpetiolar spiracle. Usually in pop-
ulations in the United States and in the
southern part of the native range near
Buenos Aires, the tuberculate postpetiolar
spiracle is smaller and not as distinct.Males
of S. richteri tend to have stronger sculp-
turing in the United States than they do in
South America.
The larval stage described by Wheeler
and Wheeler (1977) was collected in
Walker County, Alabama. At the time of
collection, this area was likely part of the
S. richteri x invicta hybrid zone (Vander
Meer et al. 1985, Vander Meer and
Lofgren 1988). These specimens proba-
bly represent the larvae of S. richteri x
invicta, rather than pure S. richteri. The
description differs from that given above
for S. richteri in several characters, the
most conspicuous of which is the stated
presence of bifid and denticulate setae on
the head capsule. This is much more
reminiscent of S. invicta. True S. richteri
larvae lack bifid setae on the head cap-
sule. The larvae differ from S. quinque-
cuspis by the presence of multi-branched
setae and fine rugae on the head capsule,
as well as being smaller in size.
Genetic studies of S. richteri in its
native range have revealed pronounced
nuclear and mtDNA differentiation
between populations from southern
Brazil and central Argentina (Ross and
Shoemaker 2005), consistent with
a long-term absence of gene flow be-
tween ants occupying these distant
parts of its range.
Solenopsis saevissima (Smith)
(Figs. 37, 38, 49, 70, 71, 73, 84, 85, 90, 91,
104, 105, 146, 147, 177, 182–184)
Myrmica saevissima F. Smith 1855: 166.
[Syntype ? worker. BRAZIL. Para
State. Tapajo´s. Bates. BMNH.]
Solenopsis moelleri Forel 1904: 174.
[MHNG.]
S. moelleri var. gracilior Forel 1904:
174. [MHNG?]
S. geminata var. incrassata Forel 1908:
362. [MHNG?]
S. geminata pylades Forel 1909: 262.
S. saevissima var. morosa Santschi 1916:
380. [NHMB.]
S. geminata saevissima var. piceaWasmann
1918: 70.
S. saevissima var. perfida Santschi 1923:
266. [NHMB.]
S. (Solenopsis) saevissima saevissima:
Creighton 1930: 80–83.
S. saevissima var. picea: Kistner 1982:
73–74.
Worker.—Head subquadrate to weakly
ovate (Fig. 147). Head sculpture with
small piligerous foveolae, <0.01 mm in
diameter. Median frontal streak absent.
Median ocellus in largest major workers
absent (Fig. 147). Mandibular costulae
present throughout. Mesonotum with
20–25 setae. Promesonotal suture in
largest major workers gently curved
medially, never projecting upward
(Fig. 146). Mesonotum weakly convex
in lateral view (Fig. 146). Propodeum
sculpture glabrous posteroventral to
spiracle (Fig. 146). Postpetiole shape
as high as or higher than broad. Post-
petiole sculpture in posterior view with
lower 0.33–0.50 transversely rugose,
upper surface glabrous and shiny. Color
generally red brown to dark brown.
Gyne.—Head. Slightly broader than
long, quadrate, sides of head convex
from eyes to occipital angles, straight to
nearly straight ventral to eyes (Fig. 38).
Eye sometimes with 3–4 setae pro-
truding from between ommatidia, setal
length £3X width of ommatidium. Me-
dian ocellus large, circular (Fig. 38).
Lateral ocelli moderate to large, slightly
ovate (Fig. 38). Clypeus projecting,
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON364
carinal teeth stout and sharp, carinae
well defined, less so dorsally, slightly
divergent ventrally (Fig. 38). Paracarinal
teeth small, sometimes poorly defined
(Fig. 38). Median clypeal tooth poorly
developed, usually absent (Fig. 38).
Approximately 0.50 of eye dorsal to
midpoint of head (Fig. 38).
Mesosoma. Parapsidal lines present
on posterior 0.50 of disk (Fig. 37). Mes-
onotum with indistinct, median furrow on
posterior one-sixth or less. Median bi-
dentate process present on metasternum.
Wing venation as in Figs. 90, 104.
Metasoma. Lateral faces of post-
petiole weakly to strongly concave.
Petiolar and postpetiolar spiracles tu-
berculate in some cases.
Coloration, Sculpturing, and Pilosity.
Piligerous foveolae small, sparse, width
<0.01 mm in diameter, larger on head
than on thorax and abdomen. Pubes-
cence simple, golden and erect, longer
and denser on head than elsewhere,
longest on anterior edge of clypeus.
Mesosoma with longest pubescence
(length >0.30 mm) 2X longer than
shortest pubescence (Fig. 37). Mandible
with 9–11 fine, distinct costulae present
throughout. Propodeum with fine striae
posteriorly, anterior 0.25 polished (Fig. 37).
Posterior surface of petiolar node with
lower 0.75 of surface with fine striae,
dorsum polished. Posterior surface of
postpetiolar node with lower 0.75 of
surface with coarse striae, 4–7 striae
present, median striae weak to obsoles-
cent laterally, dorsum polished (Fig. 49).
Remaining integument smooth and pol-
ished. Color varies from dark brown to
pale yellow on front of head, lateral
portions of mesonotum, mandibles,
mesosternum, appendages and apical
portions of gaster segments. Color
brown on vertex, interior margins of
ocelli, medial area of mesonotum,
parapsidal lines, lateral margins of T1
and preapical transverse areas on
metasomal segments. Internal margins
of ocelli dark brown. Median streak
absent.
Morphometric Measurements. L
;7.1–8.0, HW 1.3–1.8, VW 0.5–0.9, HL
1.2–1.3, EL 0.4–0.6, OD 0.1–0.2, OOD
0.15–0.25, LOW 0.08–0.15, MOW 0.13–
0.16, CD 0.15–0.22, MFC 0.20–0.25, EW
0.25–0.40, SL 0.89–1.12, PDL 0.18–0.25,
LF1 0.1–0.14, LF2 0.07–0.1, LF3 0.07–
0.12, WF1 0.09–0.12, FL 1.00–1.2, FW
0.19–0.31, MW 1.32–1.43, DLM 2.53–
2.81, PRH 0.98–1.10, PL 0.58–0.82, PND
0.51–0.61, PH 0.52–0.83, PPL 0.28–0.43,
DPW 0.48–0.83, PPW 0.60–0.91, PHB
0.27–0.51, N=13.
Male.—Head. Eye normally without
setae protruding from between omma-
tidia. Ocelli large and prominent, elliptical
(Fig. 71).
Mesosoma. Propodeum rounded, de-
clivous face perpendicular, flat except
with distinct to indistinct median longi-
tudinal depression, basal face strongly
convex transversely and longitudinally.
Metapleuron sometimes not broad,;0.33
as wide as high, but usually broader
(Fig. 70), sometimes with transverse
posterior carina. Wing venation as in
Figs. 91 and 105.
Metasoma. In cephalic view, dorsum
of node varies from transverse to bilo-
bate with deep median impression. Pet-
iolar and postpetiolar spiracles distinctly
tuberculate to not tuberculate. Genitalia
as in Figs. 84 and 85.
Coloration, Sculpturing, and Pilosity.
Pubescence short, thin, yellow, erect to
suberect and of uniform length over
body (0.15–0.20 mm), longest on gena
and vertex. Mesonotal pubescence
sparse (Fig. 72). Propodeum with base
striato-granulate, medially finely granu-
late (Fig. 70). Area between eye and
insertion of antenna, area between ocelli,
posterior portion of metapleuron, and
VOLUME 120, NUMBER 2 365
base of petiolar nodes granulate to
weakly granulate (Figs. 70, 71). Vertex
posterior to ocellar triangle glabrous
(Fig. 71). Gena weakly striate. Posterior
surface of petiolar node with lower 0.25
of surface with fine striae, lower 0.50 of
surface granulate, sometimes granula-
tions obsolescent medially, dorsum pol-
ished. Lateral faces of the scutellum
striate. Remaining integument smooth
and polished. Color generally red yellow
to yellow brown. Antennae and legs pale
yellow. Mandibles yellow.
Morphometric Measurements. L
;6.0–7.5, HW 0.89–1.10, VW 0.28–
0.51, HL 0.70–0.81, EL 0.40–0.62, OD
0.05–0.11, OOD 0.18–0.32, LOW 0.10–
0.22, MOW 0.15–0.25, CD 0.15–0.25,
MFC 0.15–0.21, EW 0.30–0.40, SL
0.15–0.20, SW 0.09–0.15, PDL 0.05–
0.12, PEW 0.09–0.15, LF1 0.10–0.21,
LF2 0.10–0.15, LF3 0.15–0.20, WF1
0.09–0.10, FL 1.00–1.12, FW 0.15–0.21,
MW 1.18–1.64, DLM 2.10–2.82, PRH
0.77–1.12, PL 0.50–0.61, PND 0.38–
0.60, PH 0.30–0.61, PPL 0.18–0.44,
DPW 0.40–1.03, PPW 0.43–0.94, PHB
0.30–0.40, N=12.
Fourth instar worker larva.—Head.
Large, subpyriform in anterior view
(height 0.40 mm, width 0.43 mm) (Figs.
177, 182). Cranium slightly broader than
long (Figs. 177, 182). Antenna with 3
sensilla, bearing spinule (Figs. 177,
182). Occipital setal row with 4–8 bifid
setae, base 0.5–0.66X total length of
seta, 0.03–0.07 mm long (Figs. 177, 182,
183). First setal row on vertex with 2
bifid setae, base ;0.66X total length of
seta, setae 0.03–0.07 mm long (Figs.
177, 182, 183). Second setal row on
vertex with 4 setae, inner 2 setae simple,
outer 2 setae with denticulate to bifid
apices, 0.09–0.10 mm long (Figs. 177,
182, 183). Setae ventral to antenna level
simple, 0.12–0.14 mm long (Figs. 177,
182). Clypeus with transverse row of 4
setae, inner setae shorter than outer se-
tae, 0.03–0.09 mm long (Figs. 177, 182).
Labrum small, short (breadth 2.3X
length) (Figs. 177, 182). Labrum with
4–6 sensilla on dorsal surface of each
half and apex with coarse isolated spi-
nules. Each half of epipharynx with 2–3
isolated and 2 contiguous sensilla.
Straight medial portion of mandible
with 2–5 teeth that decrease in size
dorsally. Maxilla with apex conical,
palpus peg-like with 5 sensilla, 2 with
spinules. Galea conical with 2 apical
sensilla, each bearing one spinule.
Labium with patch of spinules dorsal to
each palpus, spinules coarse and iso-
lated or in short rows of 2–3. Labial
palpus slightly elevated with 4–5 sen-
silla, each bearing one spinule.
Body. Spiracles small, first spiracle
slightly larger than others. Body setae
of 2 types. Simple to denticulate setae
(0.05–0.13 mm long) arranged in
transverse row of 6–8 on ventral sur-
face of each thoracic somite and on
each of 3 anterior abdominal somites.
Bifid setae (0.05–0.08 mm long) occur
elsewhere, base ;0.5X length (Figs.
183, 184).
Length. Approximately 2.3 mm.
Material examined.—Various speci-
mens (FSCA). Also, see Appendices A
and B.
Distribution.—A light color variant
of S. saevissima occurs throughout the
Amazon basin (Fig. 201). The dark color
variant occurs south from Goais and
Bahia to Sa˜o Palo State in Brazil (Fig.
201). The dark color variant occurs
sporadically throughout the Amazon
basin.
Comments.—This species is highly
variable in both coloration and size of
the workers and gynes. They range from
the small dark forms in southern Brazil
to the large orange brown forms in
northern Brazil. These color forms are
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON366
not morphologically distinct, however,
as there is an almost continuous cline in
size and coloration. Recently, Ross et al.
(2010) were able to distinguish five
evolutionary independent lineages in
nominal S. saevissima using genetic
data (see Fig. 201). Discovery of differ-
entiating characters and formal descrip-
tion of these putative species is still
outstanding.
The gynes of S. saevissima lack meso-
notal maculae like S. electra, S. pusillignis,
and S. macdonaghi. Contrary to this, some
callow gynes have integumental macula-
tions on the mesonotum. These macula-
tions are not distinctly margined and must
fade as the gyne matures.
There is a large size variation of the
males as well. However, the distribution
is opposite to that of the workers and
gynes. The larger males are normally
found within colonies of the smaller,
dark-form workers.
Males of S. saevissima are most sim-
ilar to S. pusillignis due to their lighter
coloration and to the region of the head
posterior to the ocellar triangle being
glabrous. The males of S. saevissima
lack the large ocelli and mesonotal
maculations possessed by males of
S. pusillignis. Males of S. saevissima
tend to have the OOI (2.50–3.50) larger
than any other species (<2.70).
The larvae of S. saevissima are similar
to S. invicta. Although S. saevissima lar-
vae normally have a smaller head capsule
than S. invicta, the setal characters are
similar between the two species. Some
larval specimens of S. saevissima have
denticulate setae present on the body,
which differs from S. invicta.
As is the case with S. invicta and
S. richteri, extreme genetic differentiation
of geographic populations of S. sae-
vissima has been detected using mtDNA
sequence data as well as nuclear micro-
satellite data (Shoemaker et al. 2006, Ross
et al. 2010). In particular, specimens from
Amazonian, southeastern Atlantic, and
south-central Atlantic portions of the
Brazilian range are highly divergent
from specimens collected in central
Brazil. The various color forms in this
species are not concordant with the
major genetic lineages.
Solenopsis weyrauchi Trager
Solenopsis weyrauchi Trager 1991: 190.
[Holotype worker. “Abra Gavila´n b.
Caramarca, 2, 800 m. PERU. #709.
ex. col. Weyrauch. LACM.]
Worker.—Head ovate to subrectangular.
Head sculpture with small piligerous
foveolae, ;0.01 mm in diameter. Me-
dian frontal streak present, sometimes
consisting of 2 elongate darkened
spots. Median ocellus in largest major
workers absent. Mandibular costulae
usually well developed throughout
entire length, sometimes obsolescent
near base. Mesonotum with 30 or more
setae. Promesonotal suture in largest
major workers gently curved medially,
never projecting upward. Mesonotum
weakly convex in lateral view. Propo-
deum sculpture glabrous posteroventral
to spiracle. Postpetiole shape as high
as or higher than broad. Postpetiole
sculpture in posterior view with lower
0.50–0.75 transversely rugose, upper
surface shiny with some piligerous
foveolae present. Color of head, mes-
onotum and T1 maculation red yellow.
Remainder of gaster black brown. Pro-
podeum and dorsum of petiolar nodes
yellow brown. Sometimes rear portion
of head, frons around median streak,
and pronotum yellow brown. T1
maculations with 2 small anterolateral
spots.
Gyne.—Unavailable for study.
Male.—Unknown.
VOLUME 120, NUMBER 2 367
Fourth instar worker larva.—
Unknown.
Material examined.—Three speci-
mens from Bolivia, 6 km northeast of
Potosı´, 19° 32’ S, 65° 43’ W, 3900 m, 25.
XII.1993, P.S. Ward (UCDC). These
specimens were identified by J. C.
Trager.
Distribution.—Solenopsis weyrauchi
was previously known only from several
widely spaced locations at high eleva-
tions in the Peruvian Andes. The holotype
(unavailable for study) is from Cajamarca,
Peru (Fig. 201). As the new locality data
suggest and as Trager (1991) predicted,
the range of S. weyrauchi likely extends
throughout the Andes, at least from Peru
to Bolivia, but perhaps as far northward as
Columbia and southward as Argentina
and Chile.
DISCUSSION
Delineation of Species Groups within
Solenopsis
Trager (1991) placed the worker-poly-
morphic fire ants along with three mono-
morphic Solenopsis species (S. substituta,
S. tridens, and S. virulens) in the S. gem-
inata species-group, although he admitted
the inclusion of S. virulens was some-
what arbitrary. Trager referred to smaller
groupings within the S. geminata species-
group as species complexes, and sub-
sets of complexes as subcomplexes.
The S. geminata species-group is informal
and its monophyly has yet to be demon-
strated. This situation, coupled with the
unwieldy terminology of complexes and
subcomplexes, has led us to propose a new
classification of fire ants (Table 4).
Solenopsis virulens is placed in the
S. virulens species-group, which is de-
fined by the following: workers mono-
morphic, eye small with 20–60 facets,
first flagellomere as broad as or broader
than long, and postpetiole not dilated.
This species-group is presumably closely
related to the S. nigella species-group
sensu Moreno-Gonzalez (2001), which is
equivalent to Euopthalma of Creighton
minus S. globularia.
Solenopsis tridens and S. substituta
are placed in the S. tridens species-
group, which is defined by mono-
morphic workers with a long scape, long
first flagellomere (at least 1.5X longer
than broad), propodeal carinae, and an
elongate petiolar peduncle. This species-
group is equivalent to the S. tridens
complex of Trager.
The S. geminata species-group in-
cludes S. geminata, S. xyloni, S. am-
blychila, S. aurea, S. gayi, and S. bruesi.
This species-group is defined by strongly
polymorphic workers with a short
scape, long first flagellomere (at least
1.5X longer than broad), reduced or
absent median clypeal tooth, and
a ventral petiolar process. This species-
group is equivalent to the S. geminata
complex of Trager. No apomorphies
are apparent for the species-group, and
it may be defined entirely by symple-
siomorphies.
Finally, the S. saevissima species-group
includes S. metallica n. sp., S. daguerrei,
S. electra, S. hostilis, S. interrupta, S. in-
victa, S. macdonaghi, S. megergates,
S. pusillignis, S. pythia, S. quinquecuspis,
S. richteri, S. saevissima, and S. weyr-
auchi. This group is defined by strongly
polymorphic workers with a long scape,
long first flagellomere (at least 1.5X lon-
ger than broad), strongly developed me-
dian clypeal tooth, weak sculpturing, and
a small or absent ventral petiolar process.
This species-group is equivalent to the
S. saevissima complex of Trager.
There is some molecular support for
the monophyly of these groups (Krieger
and Ross 2005, Shoemaker et al. 2006),
although taxon sampling is incomplete
and branch support is often weak. As
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON368
such, the proposed species complexes
should be viewed as preliminary until
the evolutionary relationships of the fire
ants have been robustly estimated using
diverse charcter sets.
Morphology of Sexuals
Creighton (1930, 1950) stated that
both males and gynes of Solenopsis ap-
pear to offer better characters for specific
determinations than do the workers.
Because individuals of the sexual caste
tend to be larger than the worker caste
and have a less generalized and reduced
anatomy, they could provide characters,
such as those from male genitalia and
wing venation, that are not obtainable
from workers and are useful for identi-
fication purposes (Creighton 1930, 1950).
This study found that the amount of in-
traspecific variation occurring in the adult
males and gynes was equivalent to that
of workers, making the taxonomic in-
formation gained from these castes no
better than that obtained from workers.
Furthermore, the morphometric mea-
surements and indices (Tables 5, 6) of
the adult males and gynes alone are
inadequate for determining species.
Given a choice, workers still offer the
most reliable and numerous characters,
and these characters alone usually are
sufficient for making accurate species
identifications. Even though the mor-
phology and morphometrics of sexuals
are of limited use alone, they greatly
improve the accuracy of identifications
of fire ants when used in concert with
data for the workers.
Male Genitalia
For many Hymenoptera, the male
genitalia are of great diagnostic utility.
Sexual selection is hypothesized to often
drive the rapid divergence of the mor-
phology of male genitalia once specia-
tion occurs (Eberhard 1985). Also, because
themale genitalia are structurally complex,
the likelihood that related species would
become similar in this structure through
parallelism is low (Mayr 1969). Thus,
genitalic characters are potentially useful
for distinguishing even closely related
species. This is not the case for Sol-
enopsis. Although there are slight differ-
ences between the S. fugax species-group
and several of the other fire ant species-
groups, this study found that the male
genitalia of the species within the
S. saevissima species-group were rela-
tively homogeneous and uninformative
(Figs. 74–86). After study of the genitalia
of many Solenopsis exemplars, we also
conclude that characters used by Baroni-
Urbani (1968) to raise Diplorhoptrum to
the generic level are not found in all of
the species he placed in this taxon.
Furthermore, Diplorhoptrum species
such as S. tennesseensis and S. abdita
have genitalia more closely resembling
those of the fire ants than those of the
European Diplorhoptrum species, S. fugax.
This information provides additional
support for the synonymy of Diplorhop-
trum with Solenopsis, as proposed by
Bolton (1987).
Wing Venation
Although wing venation in Solenopsis
may provide valuable data for inferring
the higher-level phylogeny of the tribe
Solenopsidini in the future, as proposed by
Brown and Nutting (1950), it appears to be
too conservative within the S. saevissima
species-group to be phylogenetically
informative (Pitts et al. 2005). More-
over, wing venation tends to be too
similar across species and too variable
within species (Figs. 87–108) to pro-
vide diagnostic information.
Although some slight differences ex-
ist, the wing venation of the S. saevissima
species-group is remarkably similar to that
of other groups, such as the S. geminata
species-group (Figs. 109-114, 116), the
VOLUME 120, NUMBER 2 369
S. tridens species-group (Figs. 115,
117, 118), the S. globularia species-
group (Fig. 123), and some members of
the S. molesta species-group (Figs. 124–
125). Furthermore, distantly related spe-
cies such as S. nigella gensterblumi, S. nr.
nigella, and an unidentified Solenopsis
species are similar in their venation as
well (Figs. 119–122). Some species in
the S. molesta species-group have di-
agnostic wing venation, such as the re-
duction of the r-rs cross vein (Fig. 129),
but others do not (Figs. 127–129). In
general, wing venation provides few
taxonomically informative characters
for the genus.
Intraspecific variation and individual
aberrations in wing venation were com-
monly observed, including: 1) swelling
in the Rs+M vein in the radial cell of
a S. pusillignis gyne (Fig. 87) and S. richteri
gyne (Fig. 102); 2) coarseness of the Rs
vein and the veins delineating the radial
cell in individuals of several species
(Figs. 89, 93, 95); 3) swellings on the Cu
vein of a S. macdonaghi male (Fig. 97);
4) swellings on the Rs+M vein in the
median cell of a S. megergates gyne
(Fig. 98). These abnormalities are found
in other species-groups and are probably
characteristic of the genus Solenopsis as
a whole (Figs. 109, 119, 122, 125) (see
also Ross and Robertson 1990). In some
cases, certain veins are misplaced so that
the venation looks unique (Fig. 109), but
usually the other wing on the same in-
dividual is normal. Such asymmetry has
been documented forOxyepoecus, a close
relative of Solenopsis (Kempf 1974). This
variation exists as well for both spectral
and nebulous veins.
The lack of the m-cu cross vein for the
gynes of S. metallica (Fig. 89) and the
reduction of wing venation in S. da-
guerrei (Figs. 106, 108) are constant for
all specimens seen and are considered
characters rather than abnormalities. The
lack of the m-cu cross vein for S. met-
allica was observed in all four forewings
of the two gynes from different nests
examined. All specimens of S. daguerrei
had reduced wing venation, albeit to
various degrees.
Other observed morphological ab-
normalities are noted here. A single gyne
of S. megergates had two median ocelli
and had coarse striations throughout the
ocellar triangle (Fig. 54). These com-
plete striations were seen only in this
single atypical specimen. One gyne of
S. quinquecuspis had four propodeal
spiracles (Fig. 55). These two speci-
mens did not otherwise differ from the
typical gynes of their species. Lastly,
two gynandromorphs of S. quinque-
cuspis were discovered, as will be
discussed elsewhere.
Larval Morphology
Wheeler and Wheeler (1976, 1986,
1991) found that larval morphology
could be used to differentiate ant genera
and provided a generic key using larval
characters. In some cases, higher level
taxonomy of Formicidae has been re-
defined using larval morphology (Wheeler
and Wheeler 1970). Many species-level
larval descriptions have been published
for Formicidae, but in only three cases has
larval morphology been used for phylo-
genetic purposes (Wheeler and Wheeler
1970, Schultz and Meier 1995, Pitts et al.
2005).
The larval stages of ten species within
the Solenopsis saevissima species-group
are described in this study, eight for the
first time. The morphology of these
species is very similar, yet some var-
iation occurs. Wheeler and Wheeler
(1977) reported that S. invicta differed
from S. richteri x invicta (described as
S. richteri) in the number of setae on the
dorsal side of the labrum and the number
of sensilla on the ventral margin of the
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON370
labrum. The present survey of many
specimens and species revealed that
minute features such as these are quite
variable within species and thus are not
very useful in species determinations.
Mandibular dentition is of limited use
due to varying degrees of wear resulting
from feeding. Solenopsis saevissima
species-group larvae are of little sys-
tematic significance because most larval
features are broadly overlapping and
continuous among species. However,
two general groups of species can be
defined on the basis of larval characters.
One group includes those species with
bifid setae dorsal to the antennal margin
(S. metallica, n. sp., S. interrupta, S. invicta,
S. pusillignis, S. saevissima), a condition
termed the S. saevissima type. The other
group contains those species with setae
dorsal to the antennal margin that are usu-
ally simple or dentate (S. macdonaghi,
S. megergates, S. quinquecuspis, and
S. richteri), a condition termed the S. me-
gergates type. This latter type appears
on the basis of the inferred species
phylogeny to be the apomorphic con-
dition in the species-group (Pitts et al.
2005).
ACKNOWLEDGMENTS
We thank T. L. Pitts-Singer (USDA-
ARS Bee Biology and Systematics
Laboratory, Logan, Utah), S. D. Porter
(USDA-ARS), and Colin Brammer
(Department of Biology, Utah State
University, Logan) for critically review-
ing drafts of this paper; S. Cover (MCZ),
C. Flechtmann (ICIB), L. E. Gilbert
(Department of Zoology, University of
Texas, Austin), J. T. Huber (CNCI), I.
Lo¨bl (MHNG), S. D. Porter (USDA-
ARS), L.A. Stange (FSCA), L. Calca-
terra (USDA-ARS), and P. S. Ward
(UCDC) for loans of specimens; J. M.
Carpenter (AMNH), P. Folgarait (Unidad
de Investigacio´n en Interacciones Bio-
lo´gicas, Universidad Nacional de Quilmes,
Buenos Aires, Argentina), J. Heraty (De-
partment of Entomology, University of
California at Riverside), C. Kugler (Bi-
ology Department, Radford University,
Virginia), T. R. Schultz (NMNH), R. R.
Snelling (LACM), J. C. Trager (Shaw Ar-
boretum of Missouri Botanical Gardens,
Missouri), D. B. Wahl (AEIC), and
J. Wheeler for providing information
and advice for this project. We are
grateful for J. Wiley’s effort in providing
access to the large alcohol collection of
Solenopsis from the FSCA. We are
thankful for the assistance provided by
M. A. Farmer and J. A. Shields of the
Center of Ultrastructural Studies, Uni-
versity of Georgia for SEM support. The
following institutions provided support to
JPP for this study: the Canadian National
Insect Collection for a CanaColl grant for
travel to Ottawa, Canada in 1999, and
the American Museum of Natural
History for a Theodore Roosevelt
Memorial Fund grant for travel to the
Southwestern Research Station, Por-
tal, Arizona during 2000. We thank
W. Sherbrooke for his hospitality and
help during JPP’s stay at the South-
western Research Station, M. C.
Mescher for important logistic support
in South America, and T. L. Pitts-
Singer for collecting assistance while
at the SWRS. JPP is also grateful for
the financial support provided by the
University of Georgia, Department of
Entomology. GPC is grateful for the
financial support provided by the
Smithsonian Institution Peter Buck
Fellowship. This research was funded
by United States Department of Agri-
culture grant 99–35302–8629 provided
to KGR, JVM, and D. D. Shoemaker and
National Science Foundation grant
DEB-1354479 to KGR and D. D.
Shoemaker.
VOLUME 120, NUMBER 2 371
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Figs. 1‒5. 1, Head of Solenopsis gyne, dorsal view. 2, Mesosoma of Solenopsis gyne, dorsal view.
3, Mesosoma of Solenopsis worker, lateral view. 4, Head of Solenopsis gyne, lateral view. 5, Mesosoma of
Solenopsis gyne, lateral view. (anepisternum (an), axillae (ax), compound eyes (ce), ocelli (oc), clypeal teeth (cc),
katepisternum (k), median tooth (mct), mesonotum (mes), metanotum (met), metapleural spiracle (mts), meta-
pleuron (mtp), mesopleuron (msp), parapsidal lines (pl), propodeum (ppm), postpetiole (ppt), pronotum (prn),
petiole (pt), and scutellum (sct)).
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Figs. 6‒7. 6, Head of Solenopsis gyne with measurements noted, dorsal view. 7, Mesosoma of
Solenopsis worker, lateral view.
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Figs. 8‒10. 8, Petiole of Solenopsis gyne with measurements noted, lateral view. 9, Head and
mesosoma of Solenopsis male, lateral view. 10, Head of Solenopsis male, dorsal view. (anepisternum
(an), axillae (ax), compound eyes (ce), katepisternum (k), mesonotum (mes), metanotum (met), meso-
pleuron (msp), metapleuron (mt), ocelli (oc), parapsidal lines (pl), propodeum (ppm), postpetiole (ppt),
pronotum (prn), petiole (pt), and scutellum (sct)).
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Figs. 11‒15. 11, Forewing of Solenopsis gyne showing wing venation. 12, Larval head capsule of
typical Solenopsis. 13, Solenopsis larval head capsule, occipital setal row darkened. 14, Solenopsis larval
head capsule, first setal row on vertex darkened. 15, Solenopsis larval head capsule, second setal row on
vertex darkened.
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Figs. 16‒22. 16, Head of major worker of Solenopsis metallica sp. nov., dorsal view, scale = 0.22 mm.
17, Head of minor worker of S. metallica sp. nov., dorsal view, scale = 0.22 mm. 18, Mesosoma of
major worker of S. metallica sp. nov., lateral view, scale = 0.22 mm (pms = promesonotal suture).
19, Postpetiole of major worker of S. metallica sp. nov., rear view, scale = 0.22 mm. 20, Head of
gyne of S. metallica sp. nov., dorsal view, scale = 0.22 mm. 21, Mesosoma of gyne of S. interrupta,
lateral view. 22, Head of gyne of S. interrupta, dorsal view.
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Figs. 23‒28. Solenopsis gynes. 23, Mesosoma, S. invicta, lateral. 24, Head, S. invicta, dorsal.
25, Mesosoma, S. macdonaghi, latera. 26, Head, S. macdonaghi, dorsal. 27, Mesosoma, S. megergates,
lateral. 28, Head, S. megergates, dorsal.
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Figs. 29‒34. Solenopsis gynes. 29, Mesosoma, S. pusillignis, lateral. 30, Head, S. pusillignis, dorsal.
31, Mesosoma, S. pythia, lateral. 32, Head, S. pythia, dorsal. 33, Mesosoma S. quinquecuspis, lateral.
34, Head, S. quinquecuspis, dorsal.
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Figs. 35‒40. Solenopsis gynes. 35, Mesosoma, S. richteri, lateral. 36, Head, S. richteri, dorsal.
37, Mesosoma, S. saevissima, lateral. 38, Head, S. saevissima, dorsal. 39, Mesosoma, S. electra, lateral.
40, Head, S. electra, dorsal.
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Figs. 41‒52. Postpetiole of Solenopsis gynes, posterior view. 41, S. macdonaghi. 42, S. invicta.
43, S. quinquecuspis. 44, S. metallica sp. nov. 45, S. pusillignis. 46, S. pythia. 47, S. interrupta. 48, S. richteri.
49, S. saevissima. Solenopsis gynes. 50, Head of Solenopsis sp. with median frontal steak (fs), dorsal
view. 51, Mesosoma of S. pythia showing large foveolae, dorsal view. 52, Mesosoma of Solenopsis sp.
showing maculae, dorsal view.
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Figs. 53‒57. Solenopsis spp. gynes, mesonoma, and head. 53, S. pythia, lateral view. 54, Ocellar
triangle of Solenopsis quinquecuspis gyne with two median ocelli, dorsal view. 55, Propodeum of S.
quinquecuspis gyne with four propodeal spiracles, lateral view. 56, Mesosoma of male of S. interrupta,
lateral view. 57, Head of male of S. interrupta, dorsal view.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON386
Figs. 58‒63. Solenopsis males. 58, Mesosoma of S. invicta, lateral view. 59, Head of S. invicta,
dorsal view. 60, Mesosoma of S. macdonaghi, lateral view. 61, Head of S. macdonaghi, dorsal view.
62, Mesosoma of S. megergates, lateral view. 63, Head of S. megergates, dorsal view.
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Figs. 64‒69. Solenopsis males. 64, Mesosoma of S. pusillignis, lateral view. 65, Head of S. pu-
sillignis, dorsal view. 66, Mesosoma of S. quinquecuspis, lateral view. 67, Head of S. quinquecuspis,
dorsal view. 68, Mesosoma of S. richteri, lateral view. 69, Head of S. richteri, dorsal view.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON388
Figs. 70‒74. Solenopsis males. 70, Mesosoma of S. saevissima, lateral view. 71, Head of S. sae-
vissima, dorsal view. 72, Mesosomal dorsum of S. saevissima, dark form, lateral view. 73, Mesosomal
dorsum of S. interrupta, dark form, lateral view. 74, Genitalia of S. interrupta, aedeagus, upper, scale =
62 mm (dorsal apodeme (ap)); volsella, lower, scale = 25 mm (cuspis (cus) and digitus (dig)).
VOLUME 120, NUMBER 2 389
Figs. 75‒78. Genitalia of male. 75, Solenopsis invicta. 76, S. macdonaghi. 77, S. macdonaghi. 78, S.
megergates, aedeagus; upper, scale = 62 mm, volsella; lower, scale = 25 mm.
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Figs. 79‒82. Genitalia of male. 79, Solenopsis megergates. 80, S. pusillignis. 81, S. quinquecuspis.
82, S. richteri; aedeagus, upper, scale = 62 mm; volsella, lower, scale = 25 mm.
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Figs. 83‒86. 83, Genitalia of male: Solenopsis richteri. 84, S. saevissima. 85, S. saevissima. 86, S.
daguerrei; aedeagus, upper, scale = 62 mm; volsella, lower, scale = 25 mm.
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Figs. 87‒91. Solenopsis wings. 87, Forewing of S. pusillignis gyne. 88, Forewing of S. pusillignis
male. 89, S. metallica sp. nov. gyne. 90, S. saevissima gyne, light form. 91, S. saevissima male, light
form; scale = 350 mm.
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Figs. 92‒97. Solenopsis wings. 92, S. interrupta gyne. 93, Forewing of S. interrupta male.
94, Forewing of S. invicta gyne. 95, Forewing of S. invicta male. 96, Forewing of S. macdonaghi gyne.
97, Forewing of S. macdonaghi male, scale = 350 mm.
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Figs. 98‒105. Solenopsis wings. 98, S. megergates gyne. 99, S. megergates male. 100, Forewing of
S. quinquecuspis gyne. 101, S. quinquecuspis male. 102, Forewing of S. richteri gyne. 103, Forewing of
S. richteri male. 104, S. saevissima gyne. 105, Forewing of S. saevissima male, scale = 350 mm.
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Figs. 106‒112. Solenopsis wings. 106, S. daguerrei gyne. 107, S. electra gyne. 108, S. daguerrei
male. 109, S. geminata gyne. 110, Forewing of S. geminata male. 111, Forewing of S. xyloni gyne.
112, Forewing of S. xyloni male, scale = 350 mm.
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Figs. 113‒119. Solenopsis wings. 113, S. amblychila gyne. 114, Forewing of S. amblychila male.
115, S. tridens gyne. 116, S. aurea gyne. 117, S. substituta gyne. 118, S. amblychilamale. 119, Forewing
of S. nr. nigella gyne, scale = 350 mm.
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Figs. 120‒129. Solenopsis forewings. 120, Solenopsis nr. nigella male. 121, Solenopsis sp. “thief
ant” gyne. 122, S. gensterblumi gyne. 123, S. globularia littoralis gyne. 124, S. picta gyne. 125, S. picta
male. 126, S. abdita gyne. 127, S. tennesseensis male. 128, S. abdita male. 129, S. carolinensis gyne,
scale = 350 mm.
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Figs. 130‒135. Solenopsis major workers. 130, Mesosoma of S. metallica sp. nov., lateral view.
131, Head of S. metallica sp. nov., dorsal view. 132, Mesosoma of S. interrupta, lateral view. 133, Head of
S. interrupta, dorsal view. 134, Mesosoma of S. invicta, lateral view. 135, Head of S. invicta, dorsal view.
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Figs. 136‒141. Solenopsis major workers. 136, Mesosoma of S. macdonaghi, lateral view.
137, Head of S. macdonaghi, dorsal view. 138, Mesosoma of S. megergates, lateral view. 139, Head of
S. megergates, dorsal view. 140, Mesosoma of S. pusillignis, lateral view. 141, Head of S. pusillignis,
dorsal view.
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Figs. 142‒147. Solenopsis major workers. 142, Mesosoma of S. quinquecuspis, lateral view.
143, Head of S. quinquecuspis, dorsal view. 144, Mesosoma of S. richteri, lateral view. 145, Head of
S. richteri, dorsal view. 146, Mesosoma of S. saevissima, lateral view. 147, Head of S. saevissima, dorsal
view.
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Figs. 148‒151. Solenopsis larval structures. 148, Head capsule, S. metallica sp. nov., dorsal, scale =
46 mm. 149, Mandible, S. metallica sp. nov., scale = 18 mm. 150, Bifid setae on head capsule, S. metallica
sp. nov., dorsal, scale = 18 mm. 151, Head capsule, S. metallica sp. nov., dorsal, scale = 18 mm.
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Figs. 152‒159. Solenopsis larval structures. 152, Head capsule, S. interrupta, dorsal, scale = 46 mm.
153, Bifid setae on body, S. interrupta, dorsal, scale = 18 mm. 154, Mandible, S. interrupta, dorsal, scale =
18 mm. 155, Head capsule, S. saevissima, dorsal, scale = 46 mm. 156, Denticulate setae on body,
S. saevissima, dorsal, scale = 46 mm. 157, Head capsule, S. interrupta, dorsal. 158, Maxillary palpus and
galea, S. invicta, lateral. 159, Antennal setae, S. pusillignis, dorsal.
VOLUME 120, NUMBER 2 403
Figs. 160‒169. Solenopsis larval structures. 160, Head capsule of S. invicta, dorsal view, scale =
46 mm. 161, Bifid setae on head capsule of S. invicta, scale = 18 mm. 162, Head capsule of S. invicta,
dorsal view. 163, Head capsule of S. invicta, lateral view. 164, S. invicta, lateral view. 165, Head capsule
of S. macdonaghi, dorsal view, scale = 46 mm. 166, Bifid setae on body of S. macdonaghi, dorsal view, scale =
18 mm. 167, Setae on head capsule of S. macdonaghi, dorsal view, scale = 18 mm. 168, Mandible of
S. macdonaghi, dorsal view, scale = 46 mm. 169, Head capsule of S. macdonaghi, dorsal view.
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Figs. 170‒177. Solenopsis larval structures. 170, Head capsule of S. megergates, dorsal view, scale =
46 mm. 171, Antenna of S. megergates, dorsal view, scale = 18 mm. 172, Mandible of S. megergates,
dorsal view, scale = 18 mm. 173, Head capsule of S. megergates, dorsal view. 174, Head capsule of
S. megergates, lateral view. 175, S. megergates, lateral view. 176, Head capsule of S. quinquecuspis, dorsal
view. 177, Head capsule of S. saevissima, dorsal view.
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Figs. 178‒185. Solenopsis larval structures. 178, Head capsule of S. quinquecuspis, dorsal view,
scale = 46 mm. 179, Mandible of S. quinquecuspis, dorsal view, scale = 18 mm. 180, Bifid setae on head
capsule of S. quinquecuspis, lateral view, scale = 18 mm. 181, Simple setae on head capsule of
S. quinquecuspis, lateral view, scale = 18 mm. 182, Head capsule of S. saevissima, dorsal view, scale =
46 mm. 183, Head capsule of S. saevissima, lateral view. 184, S. saevissima, lateral view. 185, Head
capsule of S. richteri, dorsal view.
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Figs. 186‒194. Solenopsis larval structures. 186, Multi-branched setae on body of Solenopsis
richteri, lateral view, scale = 18 mm. 187, Multi-branched setae on body of S. richteri, lateral view, scale =
18 mm. 188, Mandible of S. richteri, lateral view, scale = 46 mm. 189, Head capsule of S. richteri, dorsal
view, scale = 46 mm. 190, Head capsule of S. pusillignis, dorsal view, scale = 46 mm. 191, Bifid setae on
head capsule of S. pusillignis, lateral view, scale = 18 mm. 192, Mandible of S. pusillignis, lateral view,
scale = 46 mm. 193, Head capsule of S. pusillignis, dorsal view. 194, Head capsule of S. pusillignis, lateral
view.
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Figs. 195‒200. Solenopsis daguerrei. 195, Head of gyne, dorsal view. 196, Head and pronotum of
gyne. 197, Mandible of gyne, dorsal view. 198, Propodeum of gyne, lateral view. 199, Head of male,
dorsal view. 200, Scape, pedicel and flagellomeres 1‒2 of male, lateral view, scale = 0.14 mm.
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON408
Fig. 201. Distribution of Solenopsis electra, S. metallica sp. nov., S. saevissima, and S. weyrauchi.
Evolutionarily independent lineages (sensu Ross et al. 2010) of S. saevissima are also indicated. Col-
lection localities from the collecting trips presented here are indicated by circles (◯). Type localities are
indicated by triangles (D), other reliable collection localities (Trager 1991) are indicated by squares (u).
VOLUME 120, NUMBER 2 409
Fig. 202. Distribution of Solenopsis interrupta, S. macdonaghi, S. megergates, S. pythia, and
S. quinquecuspis. Collection localities from the collecting trips presented here are indicated by circles (◯).
Type localities are indicated by triangles (D), other reliable collection localities (Trager 1991) are indicated
by squares (u).
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Fig. 203. Distribution of Solenopsis daguerrei, S. invicta, S. pusillignis, and S. richteri. Collection
localities from the collecting trips presented here are indicated by circles (◯). Type localities are in-
dicated by triangles (D).
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