The Catfishes of the
Neotropical Family Helogenidae
(Ostariophysi: Siluroidei)
RICHARD P. VARI
and
HERNAN ORTEGA
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY ? NUMBER 442
SERIES PUBLICATIONS OF THE SMITHSONIAN INSTITUTION
Emphasis upon publication as a means of "diffusing knowledge" was expressed by the first
Secretary of the Smithsonian. In his formal plan for the Institution, Joseph Henry outlined a
program that included the following statement: "It is proposed to publish a series of reports,
giving an account of the new discoveries in science, and of the changes made from year to year
in all branches of knowledge." This theme of basic research has been adhered to through the
years by thousands of titles issued in series publications under the Smithsonian imprint,
commencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the
following active series:
Smithsonian Contributions to Anthropology
Smithsonian Contributions to Astrophysics
Smithsonian Contributions to Botany
Smithsonian Contributions to the Earth Sciences
Smithsonian Contributions to the Marine Sciences
Smithsonian Contributions to Paleobiology
Smithsonian Contributions to Zoology
Smithsonian Folklife Studies
Smithsonian Studies in Air and Space
Smithsonian Studies in History and Technology
In these series, the Institution publishes small papers and full-scale monographs that report
the research and collections of its various museums and bureaux or of professional colleagues
in the world of science and scholarship. The publications are distributed by mailing lists to
libraries, universities, and similar institutions throughout the world.
Papers or monographs submitted for series publication are received by the Smithsonian
Institution Press, subject to its own review for format and style, only through departments of the
various Smithsonian museums or bureaux, where the manuscripts are given substantive review.
Press requirements for manuscript and art preparation are outlined on the inside back cover.
Robert McC. Adams
Secretary
Smithsonian Institution
S M I T H S O N I A N C O N T R I B U T I O N S T O Z O O L O G Y ? N U M B E R 4 4 2
The Catfishes of the
Neotropical Family Helogenidae
(Ostariophysi: Siluroidei)
Richard P. Vari
and Herndn Ortega
SMITHSONIAN INSTITUTION PRESS
Washington, D.C.
1986
A B S T R A C T
Vari, Richard P., and Hernan Ortega. The Catfishes of the Neotropical Family Helogenidae
(Ostariophysi: Siluroidei). Smithsonian Contributions to Zoology, number 442, 20 pages, 9 figures,
3 tables, 1986.?The Neotropical catfish family Helogenidae is revised. Contrary to recent
practice, a single genus Helogenes Giinther is recognized, with Leyvaichthys Dahl treated as a
synonym. Four species are recognized in the genus. Helogenes marmoratus Giinther, an inhab-
itant of black and clearwater streams, is distributed throughout the Atlantic drainages of the
Guianas and the upper Rio Orinoco of Venezuela, and within the Amazon basin has been
collected in Venezuela, Brazil, Peru, and Ecuador. Helogenes castaneus (Dahl) is known only
from the Rio Orinoco tributaries of eastern Colombia. Helogenes uruyensis Fernandez-Yepez is
evidently endemic to the vicinity of Auyantepui in the upper Rio Caroni, a southern tributary
of the Rio Orinoco in southeastern Venezuela. Helogenes gouldingi, a previously unrecognized
species, is described from a blackwater tributary of the Rio Madeira in Brazil.
Helogenes amazonae Delsman, described from an individual collected near Manaus, Brazil,
and H. unidorsalis Glodek and Carter, based on specimens from eastern Ecuador, are considered
synonyms of//, marmoratus. The presence or absence of an adipose dorsal fin, a character that
has been used to discriminate genera and species within the Helogenidae, has been found to
vary within western Amazonian populations of Helogenes marmoratus, and such variability is
hypothesized to occur in H. castaneus. A key to the species and descriptions of recognized taxa
are provided.
RESUMEN
Se revisa la familia de bagres neotropicales Helogenidae. Contrariamente a la practica reciente
se reconoce solo un genero: Helogenes Giinther; Leyvaichthys propuesto por Dahl se presenta
como sinonimo. Se consideran cuatro especies en el genero. Helogenes marmoratus Giinther,
tiene amplia distribution a traves de la cuenca atlantica de Guianas, el Alto Orinoco de
Venezuela y en la cuenca amazonica ha sido colectado en Venezuela, Brasil, Peru y Ecuador.
Helogenes castaneus (Dahl) se conoce unicamente de los tributarios del Orinoco del este de
Colombia. Helogenes uruyensis Fernandez-Yepez es evidentemente endemico de los alrededores
de Auyantepui, Alto Rio Caroni, un tributario sureno del Rio Orinoco en el sureste de
Venezuela. Helogenes gouldingi, una especie previamente desconocida, es descrita de una serie
de especimenes provenientes del sistema del Rio Madeira en Brasil.
Helogenes amazonae Delsman, descrita solamente a partir de un ejemplar colectado cerca de
Manaus, Brasil, y H. unidorsalis Glodek y Carter, basado en una muestra obtenida en el Rio
Bobonaza, en el este del Ecuador, son considerados sinonimos de H. marmoratus. La presencia
o ausencia de una aleta dorsal adiposa, un caracter que ha sido utilizado para discriminar
generos y especies dentro de Helogenidae, se ha determinado que varia entre poblaciones de
H. marmoratus de la Amazonia Occidental y tal variabilidad se hipotetiza que tambien ocurre
en H. castaneus. Se incluye una clave para las especies, descripciones de los taxa reconocidos, y
se discute en amplitud algunos caracteres importantes de la familia.
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the
Institution's annual report, Smithsonian Year. SERIES COVER DESIGN: The coral Montastrea cavernosa (Lin-
naeus).
I.ibrarv of Congress Cataloging in Publication Data
Vari, Richard P.
The catfishes of the neotropical family Helogenidae (Ostariophysi: Siluroidei).
(Smithsonian contributions to zoology ; no. 442).
Bibliography: p.
Supt. of Docs, no.: SI 1.27:442
1. Helogeneidae?Classification. 2. Catfishes?Classification. 3. Fishes?Classification. 4. Fishes
Latin America?Classification. I. Ortega, Hernan. II. Title. III. Series.
QL1.S54 no. 442 [QL638.H444] 591 s [597'.52] 86-600100
Contents
Page
Introduction 1
Methods and Materials 2
Abbreviations 2
Acknowledgments 2
Family HELOGENIDAE 3
The Adipose Dorsal Fin in the Helogenidae 4
The Caudal Skeleton in the Helogenidae 5
Genus Helogenes Giinther 6
Key to the Species of Helogenes Giinther 7
Helogenes gouldingi, new species 7
Helogenes castaneus (Dahl), new combination 9
Helogenes uruyensis Fernandez-Yepez, new status 12
Helogenes marmoratus Giinther 13
Literature Cited 19

The Catfishes of the Neotropical
Family Helogenidae
(Ostariophysi: Siluroidei)
Richard P. Vari
and Herndn Ortega
Introduction
The Neotropical catfish family Helogenidae is a distinc-
tive group of small-sized fishes typically inhabiting the
smaller blackwater and clearwater streams of the Atlantic
drainages of the Guianas, the Rio Orinoco tributaries flow-
ing off the Guayana Shield and the piedmont of the Colom-
bian Andes, and a variety of river systems within the Ama-
zon basin. The evidently spotty distribution of the family
within this broad geographic expanse is probably more
reflective of the secretive nature of the various species than
actually representative of the true range of its members.
Further collecting activities in appropriate habitats will un-
doubtedly both fill in gaps within the currently known range
of the family and extend those limits farther outwards, most
notably in the Orinoco and Amazon basins.
The first member of the family known to science, Helo-
genes marmoratus, was described by Giinther (1863:443)
from two specimens collected in the Essequibo River system
of British Guiana (the present Guyana). Giinther expanded
the originally very brief account of the species the following
year in his catalogue (1864:66). That more comprehensive
description was the basis for citations of the species by
Eigenmann and Eigenmann (1888:120, 1891:35) and Ei-
genmann (1910:398), and was paraphrased by Eigenmann
and Eigenmann (1890:312) in the description of the species
in their monograph on the catfishes of South America.
Forty-five years passed between the original report of the
species and its second collection by Eigenmann at several
localities in British Guiana during his expedition of 1908.
Those more extensive series of specimens served as the basis
Richard P. Vari, Division of Fishes, Department of Vertebrate Zoology, National
Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560;
Herndn Ortega, Museo de Historic Natural, Universidad Nacional Mayor de
San Marcos, Apartado 11434, Lima 14, Peru.
for the redescription 'of the species by that author (Eigen-
mann, 1912:207) and for the first illustration of the fish. In
the same publication Eigenmann removed Helogenes from
the Hypophthalmidae, to which it had been assigned pre-
viously, and described a new family, the Helogeneidae
(= Helogenidae, see family discussion), consisting of the
single contained species Helogenes marmoratus. That species
has subsequently been reported from localities in Surinam
(Steindachner, 1915:86; Boeseman, 1952:182, 1953:9,
1954:20), French Guiana (Mees, 1983:56), Brazil (Stein-
dachner, 1915:86), and Peru (Ortega and Vari, 1986:16).
The Helogenidae remained monotypic for nearly eight
decades until Delsman (1941:80) described a second nomi-
nal form, Helogenes amazonae, based on a single specimen
collected in the vicinity of Manaus, Brazil. Dahl (1960:303)
increased both the generic and specific taxonomic diversity
of the family with his description of Leyvaichthys castaneus
from the Rio Guayabero of southeastern Colombia. Helo-
genes was subsequently further expanded by the description
of a subspecies, H. marmoratus uruyensis (Fernandez-Yepez,
1967:166), from the Rio Uruyen of southeastern Vene-
zuela, and by the proposal of a third nominal species, H.
unidorsalis, from eastern Ecuador by Glodek and Carter
(1978:75). The anatomy of the Weberian Apparatus and
associated bones of Helogenes was described by Chardon
(1968:152). Lundberg and Baskin (1969) discussed aspects
of its caudal skeleton morphology, and Lundberg (1975)
described features of the cranial anatomy of the genus.
Our recent sampling of the ichthyofauna of the Rio
Madre de Dios drainage system of southeastern Peru re-
vealed populations of a helogenid species demonstrating
unexpected variation in some morphological features. This
variability leads us to an appraisal of the utility of some
characters in distinguishing nominal genera and species
within the Helogenidae. The most notable of the evidently
1
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
plastic characters found in these Peruvian populations in-
volved the size of the adipose fin, which covered the spec-
trum from relatively small, through very small, to being
totally absent. Such variability at the population level was
troublesome because the presence or absence of that fin
had been used to distinguish, wholly or in part, the genus
Leyvaichthys from Helogenes and to delimit H. unidorsalis
within Helogenes. Further examination of other helogenid
material from diverse regions of the Neotropics indicated
that the resolution of the question of the significance of this
variability, and other systematic problems, necessitated a
revisionary study of the family based on extensive, more
geographically encompassing series of specimens.
METHODS AND MATERIALS.?Counts of anal- and caudal-
fin rays were made on specimens and confirmed in many
cases by examination of radiographs. The two, or more
rarely three, anterior anal-fin rays are relatively small and
are not always readily apparent in external examination,
particularly in more recently collected specimens with
darkly pigmented anal fins. Damaged and regenerated cau-
dal-fin rays in some rare instances present externally spu-
rious fin ray counts, which can be resolved via examination
of radiographs. The vertebral count is the number of free
vertebrae posterior to the anterior vertebral (Weberian)
complex and includes the fused PU1+U1 complex as a single
element. That count does not include the five vertebrae
incorporated into that complex (Chardon, 1968:155; per-
sonal observation), which cannot be discriminated in radi-
ographs. The numbers in parentheses that follow a partic-
ular count of free vertebrae are the number of radi-
ographed specimens with that count. In the "Key" and
species accounts, subunits of the head are presented as
proportions of head length (HL). Head length itself and
measurements of medial mandibular barbel length and of
body parts are given as proportions of standard length (SL).
In the species descriptions the value of the holotype or
lectotype for a count, when available, is given in brackets.
The "Material Examined" section of each species account
is arranged in the following sequence: total number of
specimens of the species examined (in parentheses the num-
ber of specimens forming the basis for the presented mer-
istic and morphometric data, and the range of standard
lengths (in mm) for these specimens), collection locality of
the specimens, institutional abbreviation, register numbers,
number of specimens in the lot (in parentheses the number
of specimens in the lot from which counts and measure-
ments were taken, if less than the total number of specimens,
and the standard lengths (in mm) of those individuals). In
some instances anal-fin ray counts were taken from speci-
mens that were not used for other counts and measure-
ments.
The various helogenid species demonstrate a high degree
of morphological uniformity in numerous characters. In
order to reduce repetition in the species accounts, such
invariant characters are described in the family diagnosis,
but typically are not repeated in the subsequent species
descriptions.
ABBREVIATIONS.?The following abbreviations for insti-
tutions and collections are used.
AFY Augustin Fernandez-Yepez, personal collection
(material later transferee! to MAC, then to
MBUCV)
AMNH American Museum of Natural History, New York
ANSP Academy of Natural Sciences of Philadelphia
BMNH British Museum (Natural History), London
CAS California Academy of Sciences, San Francisco
FMNH Field Museum of Natural History, Chicago
IRSNB Institut Royal des Sciences Naturelles de Bel-
gique, Brussels
MAC Ministerio de Agriculture y Cria, Caracas (collec-
tions now at MBUCV)
MBUCV Museo de Biologia, Instituto de Zoologia Tropi-
cal, Universidad Central de Venezuela, Caracas
MZUSP Museu de Zoologia da Universidade de Sao Paulo
NMNH National Museum of Natural History, Smithson-
ian Institution, Washington, D.C.
NMW Naturhistorisches Museum, Vienna
UF University of Florida, Florida State Museum,
Gainesville
USM Museo de Historia Natural de la Universidad Na-
cional Mayor de San Marcos, Lima
USNM former United States National Museum collec-
tions deposited in the National Museum of Natu-
ral History, Smithsonian Institution, Washington,
D.C.
ZMA Zoologisch Museum, Amsterdam
ACKNOWLEDGMENTS.?We are indebted to the following
individuals and institutions for the loan and exchange of
specimens, information, hospitality during visits, and other
assistance: Donn E. Rosen, Gareth Nelson, and M. Norma
Feinberg (AMNH); Barry Chernoff and William Saul
(ANSP); P. Humphry Greenwood and Gordon J. Howes
(BMNH); William Eschmeyer, Tomio Iwamoto, and Pearl
Sonoda (CAS); Robert K. Johnson and Terry Grande
(FMNH); J.-P. Gosse (IRSNB); Francisco Mago-Leccia and
Antonio Machado-Allison (MBUCV); Heraldo Britski,
Naercio Menezes, and Jose Lima de Figueiredo (MZUSP);
Harald Ahnelt (NMW); George Burgess and Carter Gilbert
(UF); Han Nijssen and Isaac Isbriicker (ZMA); Michael
Goulding (Museu Paraense "Emilio Goeldi," Belem); Plu-
tarco Cala (Universidad Nacional, Bogota); and Gordon and
Sally Reid (Horniman Museum, London).
The collection of many of the series of specimens re-
ported in this paper was facilitated by the assistance of the
following individuals who participated in collecting expedi-
tions with the senior author in the cited countries: Lynne
R. Parenti (Surinam), Susan L. Jewett (Peru), and Antonio
Machado-Allison, Otto Castillo, Carl J. Ferraris, Jr., and
Justa Fernandez (Venezuela). Field studies undertaken as
part of this project were supported by the I.E.S.P. Neotrop-
ical Lowland Research Program and by the Scholarly Stud-
NUMBER 442
ies Program of the Smithsonian Institution. Research asso-
ciated with this study in Peru and at NMNH was funded by
the former program. Field studies by the junior author in
southeastern Peru were supported by the Instituto Veteri-
nario de Investigaciones Tropicales y de Altura of the
Universidad Nacional Mayor de San Marcos (UNMSM) and
the Instituto de Investigaciones de la Amazonia Peruana.
Research facilities and other assistance were provided by
the Museo de Historia Natural of UNMSM, Lima. Figures
3, 5, 6, 7, and 8 were prepared by Theophilus Britt Gris-
wald. Technical assistance at NMNH was provided by An-
drew G. Gerberich, Kurt A. Bruwelheide, and Ann M.
Williams. This paper benefitted from the comments and
suggestions of Dr. Stanley H. Weitzman, Dr. Wayne C.
Starnes, Dr. Isaac Isbriicker, Dr. Han Nijssen, Dr. John G.
Lundberg, Mr. Carl J. Ferraris, Jr., and an anonymous
reviewer.
Family HELOGENIDAE
DIAGNOSIS.?Small-sized fishes; largest individual exam-
ined 73.0 mm SL. Body naked, trunk and tail laterally
compressed, without bony plates; middorsal groove often
extending between posterior end of head and origin of
rayed dorsal fin. Dorsal fin length short, base constricted,
origin of fin located distinctly closer to hypural joint than
to tip of snout, with five rays. Dorsal and pectoral fins
lacking spines. Pectoral-fin margin rounded, moderately
developed; appressed fin reaching to region of vertical line
through origin of pelvic fin, with seven rays, lateral fin ray
unbranched. Anal fin elongate, margin straight or slightly
convex anteriorly, rounded posteriorly, base fleshy. Anal-
fin rays 32 to 49. Anterior two or three anal-fin rays small,
often enveloped by anteriorly fleshy basal portion of fin;
first and sometimes second ray not associated with a proxi-
mal pterygiophore. Anterior 15 or more anal-fin rays un-
branched. Origin of anal fin proximate to rear portion of
pelvic fins, distinctly anterior of vertical through origin of
dorsal fin. Pelvic fin relatively short, margin rounded, with
six rays, lateral fin-ray unbranched; posterior portion of
appressed fin reaching beyond origin of anal fin. Adipose
dorsal fin present or absent, when present small to minute;
with an associated basal cartilaginous element similar in
form to a proximal radial. Caudal fin forked, ventral lobe
larger and longer than dorsal lobe. Fifteen or 16 principal
caudal-fin rays; seven principal rays in dorsal lobe of fin,
eight or nine in ventral lobe of fin.
Head relatively wide, profile rounded; with thick, loose,
fleshy covering. Eyes small, dorsally located, orbital margin
not free. Gill opening extending far forward ventrally,
membranes free from isthmus. Six simple barbels, nares
without barbels. Maxillary barbel moderately developed,
extending posteriorly in a groove under eye. Mandibular
barbels moderately developed, medial pair usually longer
than lateral pair, sometimes subequal. Mouth relatively
wide. Upper jaw longer than lower, extending posteriorly
to beyond vertical through anterior margin of eye, some-
times to vertical through posterior margin of eye. Lips
fleshy. Margin of lower jaw crescent-shaped in ventral view.
Two rows of teeth on premaxilla in juveniles, inner row
lost in adults of some species, teeth of inner row smaller
than those of outer, often difficult to locate in fleshy lining
of mouth. Lower jaw with a band of cardiform teeth, teeth
of outermost row somewhat enlarged. Two separate patches
of teeth on vomer; teeth of pharyngeal tooth plates on
dorsal and ventral portions of gill arches unicuspidate,
conical. Gill rakers very short. Twelve or 13 branchiostegal
rays.
Five vertebrae in anterior vertebral (Weberian) complex;
free vertebrae posterior to complex 36 to 40; 36 and 40
relatively rare. Hypurals one and two fused, joined to
PUi+Ui; hypurals three and four and U2 autocentrum
fused into a single autogenous complex; hypural five autog-
enous (Figure 1). Secondary hypurapophysis present on
element formed by fused first and second hyurals. One
epural.
Overall coloration on head and body brown to dark
brown, dark pigmentation of body extending onto basal
one-third of caudal fin; dark coloration on caudal fin with
a discrete vertical posterior margin.
ECOLOGY.?Helogenes species typically inhabit clear or
blackwater streams either in rain or gallery forests.
REMARKS.?Giinther, in his original description of Helo-
genes (1863:443), did not assign the genus to a taxon of
higher rank. The following year in his "Catalogue of Fishes"
(1864:66) he placed Helogenes in his group Hypophthalmina
along with the Neotropical freshwater genus Hypophthal-
mus. The association of those two genera was continued by
Eigenmann and Eigenmann( 1888:120, 1890:312, 1891:35)
and Eigenmann (1910:398), who recognized a family Hy-
pophthalmidae that consisted of Helogenes and Hypophthal-
mus. In 1912 Eigenmann (p. 207) removed Helogenes mar-
moratus, the then only known species in the genus, to its
own family, the Helogeneidae (= Helogenidae). In his key
to the catfishes of British Guiana (1912:119) he noted a
series of differences between the Helogenidae and the Hy-
pophthalmidae (sensu stricto) but did not elaborate on these
characters in the text. Although he commented later in the
same work (p. 207) on the similarities between the two
families, particularly the relatively long anal fin and poste-
rior position of the rayed dorsal fin, he nonetheless con-
cluded that Helogenes "differed from it [Hypophthalmus] in
so many other essential characters that it is but remotely
related to that genus." Eigenmann did not hypothesize an
alternative phlyogenetic relationship for the Helogenidae.
A discrete family Helogenidae was subsequently recog-
nized by Regan (1911:573), Jordan (1923:150), Berg
(1940:449), Gosline (1945:53), and Greenwood el al.
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
(1966:396). Bertin and Arambourg (1958:2306), in a sig-
nificant systematic realignment, placed Helogenes in their
broadly defined Schilbeidae that also included the Old
World Pangasiidae and Schilbeidae together with the Neo-
tropical Hypophthalmidae. In his description of Leyvaichthys
castaneus, a new genus and species of helogenids, Dahl
(1960:304) suggested that the Helogenidae might be "phy-
logenetically allied" to the Neotropical family Cetopsidae.
Chardon (1968:152) described the anatomy of the Weber-
ian Apparatus and associated systems in Helogenes, and
noted similarities of that genus with the catfishes of the Old
World families Siluridae and Schilbeidae and the Neotrop-
ical families Diplomystidae and Trichomycteridae. In the
classification summarizing his conclusions, that author
(1968:225) created the superfamily Helogeneoidae for Hel-
ogenes and allied that taxon with the Old World superfami-
lies Siluroidae and Amblycipitoidae. The three superfami-
lies together constituted his Siluroidei. Lundberg and Bas-
kin (1969:14, 17, 41) discussed the caudal-fin osteology of
Helogenes marmoratus, but were unable to make a definitive
statement about the phylogenetic relationships of the spe-
cies based on information from that body system. Most
recently Gery (1984:358) suggested that the family is prim-
itive, but did not place that statement in an explicit phylo-
genetic context. In light of the divergent alternative hy-
potheses on the relationships of the family that have been
advanced by different authors, and in the absence of a
phylogenetic hypothesis based on derived characters from
multiple body systems, we prefer to retain a separate Hel-
ogenidae within the Siluroidei (sensu Fink and Fink, 1981)
without formally aligning the family with a more inclusive
taxon within that order.
Eigenmann (1912) in his original description of the family
used the name Helogeneidae, a practice followed by most
of the authors who published on the group during the
following seven decades. Steyskal (1980:174) pointed out
that Helogeneidae was an incorrect derivation of a family
name based on Helogenes, because "Names ending in -es
drop that syllable for their stems" in forming the family
name. As such the stem derived from Helogenes is "Helo-
gen," and the correct spelling of the family name is Helo-
genidae.
THE ADIPOSE DORSAL FIN IN THE HELOGENIDAE
In his original description of Leyvaichthys, Dahl
(1960:302) distinguished that genus from Helogenes partially
on the basis of the lack of the small adipose dorsal fin, the
possession of which was considered characteristic of the
latter genus. More recently Glodek and Carter (1978:77)
in their description of Helogenes unidorsalis distinguished
their species from other nominal taxa in the genus partly
due to the absence of an adipose fin.
The presence and degree of development of the adipose
dorsal fin is variable in the series of specimens of Helogenes
marmoratus we collected in the Rio Madre de Dios basin of
southeastern Peru (USNM 264030; USM 1595; USM
1596). Those 28 specimens collected in a small brook drain-
ing into the Rio Tambopata show a gradient in adipose-fin
size. Twelve individuals have relatively small adipose fins,
nine specimens have very small, reduced adipose fins, three
examples have greatly reduced, vestigial fins, and adipose
fins were completely lacking in the remaining four speci-
mens. These four classes of specimens are otherwise insep-
arable meristically and morphometrically (Table 1). This
continuum in adipose-fin size indicates that the presence or
absence of the fin is intraspecifically variable at least within
some populations of Helogenes marmoratus. In the Helogen-
idae such within-species variability in the relative size of the
adipose fin also occurs in populations of//, castaneus and it
is further hypothesized that the fin is absent in some mem-
bers of that species (see "Remarks" under H. castaneus).
Comparable intraspecific variability in the presence of a
small adipose dorsal fin occurs in the auchenipterid catfish
Auchenipterus nuchalis (Spix), which typically has an adipose
fin. Ceratocheilus osteomystax described by Miranda Ribeiro
(1918:644), and placed into the synonymy of Auchenipterus
nuchalis by Mees (1974:22), was originally delimited in part
by its lack of an adipose fin, a character that has on further
analysis proved to be intraspecifically variable. Intraspecific
variability in the presence or absence of an adipose fin
among other ostariophysans has also been reported within
the Characiformes for the lebiasinids Nannostomus eques
Steindachner (1876:126), N. harrisoni Eigenmann (Weitz-
man, 1966:6, 39), and the characid Klausewitzia aphanes
Weitzman and Kanazawa (1977:155). Such intraspecific
variability was also the basis for the description of the invalid
curimatid genus Curimatoides by Fowler (1940:255) (per-
sonal observation, R.P.V.).
The variability in the presence and size of the adipose
dorsal fin within populations of Helogenes marmoratus, H.
castaneus, and other Neotropical siluroids and characiforms
indicates that the presence or absence of the fin, particularly
when the fin is typically relatively small, is of questionable
utility in independently delimiting taxa at the specific and
supraspecific levels.
The variability in the presence or absence of the adipose
fin within Helogenes is apparently limited to populations
along the western rims of the Amazon and Orinoco drain-
age basins. Whereas Helogenes marmoratus typically has an
adipose fin, that structure is not developed in some individ-
uals from southeastern Peru (material cited above) and
eastern Ecuador (type series of//, unidorsalis, = H. marmor-
atus). Helogenes castaneus from eastern Colombia is hypoth-
esized to demonstrate comparable variability in the devel-
opment of the structure (see "Remarks" under that species).
This geographic pattern may, however, be primarily a con-
sequence of the relatively more intensive, though by no
NUMBER 442
TABLE 1.?Morphometrics and anal-fin ray count variation in specimens of Helogenes marmoratus with
different degrees of development of the adipose dorsal fin (number of specimens in parentheses). All
material from same stream in the Rio Madre de Dios system of southeastern Peru (USNM 264030, 19
specimens; USM 1595, 4 specimens; USM 1596, 5 specimens). (Standard length is expressed in mm;
measurements 1 to 11 are proportions of standard length, 12 to 16 are proportions of head length.)
Standard length
1. Snout to origin of dorsal fin
2. Snout to origin of pelvic fin
3. Snout to origin of anal fin
4. Length of base of anal fin
5. Distance between rayed and adipose dor-
sal fins
6. Greatest body depth
7. Depth of caudal peduncle
8. Length of medial mandibular barbel
9. Length of pectoral fin
10. Length of pelvic fin
11. Head length
12. Interorbital width
13. Snout length
14. Orbital width
15. Length of postorbital portion of head
16. Gape width
Anal-fin rays
Small
(12)
31.0-62.5
0.63-0.68
0.33-0.37
0.38-0.48
0.50-0.57
0.09-0.13
0.17-0.23
0.10-0.13
0.27-0.38
0.20-0.24
0.09-0.13
0.20-0.22
0.43-0.52
0.34-0.50
0.09-0.13
0.46-0.63
0.48-0.62
43-48
Reduced
(9)
50.9-65.3
0.64-0.69
0.33-0.37
0.43-0.45
0.54-0.58
0.10-0.13
0.19-0.24
0.12-0.15
0.28-0.33
0.21-0.23
0.10-0.13
0.18-0.22
0.46-0.53
0.31-0.45
0.08-0.12
0.49-0.59
0.54-0.68
43-46
Vestigial
(3)
39.1-47.9
0.66-0.67
0.35-0.37
0.43-0.45
0.54-0.57
0.10-0.11
0.17-0.21
0.11-0.13
0.29-0.34
0.21-0.22
0.10-0.12
0.20-0.21
0.48-0.51
0.35-0.42
0.09-0.13
0.54-0.57
0.57-0.59
43-45
Absent
(4)
42.2-63.0
0.63-0.66
0.36-0.37
0.39-0.44
0.55-0.56
-
0.20-0.23
0.11-0.12
0.23-0.32
0.19-0.24
0.11-0.13
0.17-0.21
0.46-0.49
0.33-0.39
0.09-0.12
0.51-0.58
0.52-0.60
43-46
means satisfactory, collecting efforts that have taken place
in the western portions of Amazonia and the Orinoco basin
than reflective of the true geographic limits of such mor-
phological variability.
T H E CAUDAL SKELETON IN THE HELOGENIDAE
Lundberg and Baskin (1969), in their analysis of the
caudal fin skeleton of various groups of catfishes, were
limited in their comparative studies of the Helogenidae in
having access only to specimens of Helogenes marmoratus
and by the availablity of only a single cleared and stained
individual of the species. Examination of a more extensive
series of cleared and stained specimens has revealed addi-
tional variability in one of the characters they discuss, and
indicates that the specimen they reported on was evidently
abnormal in the form of the element they termed the U2
autocentrum.
Lundberg and Baskin (1969:35, table 2) cite the Helo-
genidae as being characterized by the possession of 16
principal caudal-fin rays, with seven rays in the upper lobe
and nine in the lower lobe of the fin. Our examination of
more extensive series of specimens has confirmed that count
for Helogenes marmoratus Gunther and H. uruyensis Fernan-
dez-Yepez. The two other recognized species, H. castaneus
(Dahl) and H. gouldingi described in this paper, have the
number of principal caudal-fin rays reduced to 15, with
only eight principal rays present in the lower lobe of the
fin. If a decreased number of caudal-fin rays is indeed
derived (Lundberg and Baskin, 1969:34), then the presence
of only eight rays in the lower lobe of the caudal fin can be
hypothesized to be an advanced condition indicating that
H. castaneus and H. gouldingi are sister species.
Lundberg and Baskin (1969:17, table 1, fig. 7a) also note
that Helogenes is unique among the catfishes they examined
in having an autogenous Uj autocentrum, which is separate
from both the fused PU|+Ui and the single compound
upper hypural element (hypurals three and four). Exami-
nation of 12 cleared and stained specimens off/, marmoratus
from Guyana, Venezuela, and Peru, and an individual of
H. gouldingi, along with reference to radiographs of over
100 other specimens of all nominal forms has shown that
although the U2 autocentrum of helogenids is free from the
PUi+Ui compound centrum, it is, nonetheless, fused to the
compound upper hypural element derived from the third
and fourth hypurals (Figure 1). The specimen reported on
by Lundberg and Baskin was presumably aberrant in having
a totally autogenous Uj autocentrum. The form of the U2
autocentrum and neighboring ossifications in helogenids
rather than being unique among catfishes is instead com-
parable to the association of those elements reported by
those authors (1969:7, table 1) for most of the Neotropical
family Aspredinidae and some members of the Old World
families Amblycipitidae and Mochokidae.
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
-2
FIGURE 1.?Helogenes marmoratus, USM 1595, caudal skeleton (E = epural,
H = hypurals (1 to 5), HS = hemal spine, NS = neural spine, PH =
parhypural, SH = secondary hypurapophysis, U2 = second ural centrum).
Genus Helogenes Giinther
Helogenes Giinther, 1863:443 [type-species: Helogenes marmoratus Giinther,
1863, by monotypy].
Leyvaichthys Dahl, 1960:302 [type-species: Leyvaiththys castaneus Dahl, 1960
(= Helogenes castaneus), by original designation; new synonymy].
Levairhthys.?Glodek and Carter, 1978:76 [misspelling of Leyvaichthys].
DIAGNOSIS.?As for the family.
REMARKS.?Dahl (1960:304) in his original description
of Leyvaichthys distinguished his genus from Helogenes be-
cause "There is no vestige whatsoever of an adipose fin . . .
the position far back of the dorsal fin, the very large number
of anal rays and the peculiar dentition." As discussed above
(see "The Adipose Dorsal Fin in the Helogenidae"), the
presence of an adipose fin and its size, when present, are
variable at least within western Amazonian populations of
Helogenes marmoratus. The size of the fin is relatively vari-
able in some populations of H. castaneus from Colombia,
and it would appear that there is intraspecific variability in
the presence of the adipose fin in that species (see "Remarks"
under H. castaneus). The absence of the fin is consequently
not considered to be an appropriate basis for delimiting a
second genus within the family.
In his table detailing the morphometric values of the
holotype of Leyvaichthys castaneus, Dahl (1960) indicates that
the distance from the snout to the origin of the rayed dorsal
fin in that specimen is 0.665 of "skeletal length " (presum-
ably standard length). That value agrees well with the range
for that measurement in the material identified as Helogenes
castaneus in this study (0.65-0.71 of SL), but more signifi-
cantly relative to the question of the recognizability of
Leyvaichthys, that value is overlapped by the ranges for that
measurement found in examined specimens of Helogenes
marmoratus (0.52-0.71 of SL) from diverse portions of the
geographic distribution of that species. As such, that mor-
phometric character is not useful in delimiting those nomi-
nal species, let alone the two genera. The number of anal-
fin rays cited by Dahl (45 to 49) differed significantly from
the 37 to 40 listed by Eigenmann (1912:208) for Essequibo
River H. marmoratus, but overlapped the 41 to 46 anal-fin
rays cited for the species by Steindachner (1915:87), and is
within the range of anal-fin rays of H. marmoratus found in
this study (39 to 48). Thus anal-fin ray numbers also fail to
delimit Leyvaichthys from Helogenes.
Dahl characterized Leyvaichthys as having a single row of
teeth on the premaxilla, whereas Helogenes marmoratus has
two rows of teeth on that element. The specimens identified
as Helogenes castaneus in this study demonstrate what ap-
pears to be ontogenetic variability in the number of tooth
rows on the premaxilla. Specimens of approximately 36 to
42 mm SL have a complete outer row of dentition and a
less well-developed inner row of smaller teeth often limited
to the lateral margins of the jaw. The inner tooth row is
lacking in the 40 to 47 mm SL specimens of the species
examined. Because the type series reported on by Dahl
consisted of individuals of over 47 mm SL, the observed
lack of the inner premaxillary teeth in those specimens can
be assumed to have been a consequence of a similar process
of ontogenetic loss.
Dahl described the outer row of teeth in each jaw of
Leyvaichthys as having serrated edges. Such a modification
of the smooth conical teeth typical for most catfishes has
not been found in the specimens herein equated with Hel-
ogenes castaneus, nor are they present in any other member
of the family. In the absence of the type series of Leyvaichthys
castaneus on which we could confirm this character, and
given the evident lack of such dentition in catfishes, along
with the absence of tooth serrations in Colombian helogenid
material that otherwise fits the description of Leyvaichthys
castaneus, we assume that the reported presence of tooth
serrations on the outer tooth rows in that species represents
an erroneous observation.
The characters listed by Dahl as separating Leyvaichthys
from Helogenes either fail to distinguish even the single
contained nominal species at the specific level (absence of
adipose fin, relative length from snout tip to origin of rayed
dorsal fin, anal-fin ray count), delimit only the largest adults
(number of premaxillary tooth rows) or, in the case of the
reported tooth serrations, are considered to represent, in
the light of available information, an erroneous observation.
Only the absence of an inner tooth row on the premaxilla
NUMBER 442
of larger specimens distinguishes Helogenes castaneus from
the three other species in the family. We prefer not to
formalize this minor dentitional difference at the generic
level, given our current uncertainty as to the relationships
of the various helogenid species. Furthermore, the recog-
nition of Leyvaichthys for the species herein termed Helogenes
castaneus would mean that the genus Helogenes, thus re-
stricted to the three other species in the family, would be
defined by the retention of an inner row of premaxillary
teeth in the adults, a primitive character. Such a primitive
character is not an appropriate basis for advancing a hy-
pothesis that the genus Helogenes, in such a restricted sense,
would constitute a natural assemblage. Indeed the only
character uncovered possibly pertinent to the question of
intrafamilial relationships, the reduced number of principal
rays in the lower lobe of the caudal fin (see "The Caudal
Skeleton in the Helogenidae"), suggests that Helogenes cas-
taneus is more closely related to H. gouldingi than the latter
species is to the remaining members of the family. If that
hypothesis of relationships is correct, the separation of H.
castaneus in Leyvaichthys and the alignment of H. gouldingi
with H. marmoratus and H. uruyensis in Helogenes would
result in the latter genus being non-monophyletic, because
it would not consist of all descendants of the hypothesized
common ancestor. For these reasons Leyvaichthys Dahl is
herein placed into the synonymy of Helogenes Giinther.
Key to the Species of Helogenes Giinther
1. 15 principal caudal fin rays; with eight principal rays on lower lobe of caudal
fin 2
16 principal caudal fin rays; with nine principal rays on lower lobe of caudal fin
3
2. 39 to 43 anal rays. Distance from tip of snout to origin of rayed dorsal fin 0.57-
0.60 of SL. Snout length 0.36-0.40 of HL. Distance between rayed dorsal
fin and adipose dorsal fin 0.16-0.19 of SL H. gouldingi, new species
43 to 49 anal rays. Distance from tip of snout to origin of rayed dorsal fin 0.65-
0.71 of SL. Snout length 0.27-0.36 of HL. Distance between rayed dorsal
fin and adipose dorsal fin 0.11-0.15 of SL
H. castaneus (Dahl), new combination
3. 32 to 37 anal-fin rays H. uruyensis Fernandez-Yepez, new status
39 to 48 anal-fin rays H. marmoratus Giinther
Helogenes gouldingi, new species
FIGURES 2-4
DIAGNOSIS.?The possession of 15 principal caudal-fin
rays, with eight principal rays in the lower lobe of the fin,
distinguishes Helogenes gouldingi from both//, uruyensis and
H. marmoratus, which have 16 principal caudal-fin rays, with
nine principal rays in the lower lobe of the fin. The 39 to
43 anal-fin rays of Helogenes gouldingi further separate it
from H. uruyensis, which has 32 to 37 rays. Helogenes goul-
dingi and H. castaneus are separable in the number of anal-
fin rays (39 to 43 versus 43 to 49), relative snout lengths,
and relative distance between the rayed and adipose dorsal
fins. Differences in the relative distances from the snout to
the origin of the pelvic fin, and snout to the origin of the
anal fin, and relative lengths of the base of the anal fin, and
medial mandibular barbel further distinguish H. gouldingi
from H. uruyensis (see "Key," Figure 2, and Table 2).
DESCRIPTION.?Morphometrics of the holotype and par-
atypes are given in Table 2.
Dorsal profile of body smooth, slightly convex from snout
to dorsal margin of caudal peduncle. Ventral profile of
body gently curved from lower jaw to pelvic-fin origin. Base
30-
SD
20
30 40
SL
50
FIGURE 2.?Graph of distance from tip of snout to origin of rayed dorsal
fin (SD) against standard length (SL) for Helogenes gouldingi, new species
(A), and Helogenes castaneus (B) (both in millimeters, with regression lines
for each species; rj=0.97, regression lines significantly different [P=0.05]).
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
FIGURE 3.?Helogenes gouldingi, new species, holotype, MZUSP 28854, 46.5 mm SL; Rio Madiera,
Amazonas, Brazil.
TABLE 2.?Morphometrics of the species of Helogenes. (Standard length is expressed in mm; measurements 1 to 11 are proportions of standard length; 12
to 16 are proportions of head length. See "Material Examined" for each species for information on measured specimens.)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
II.
12.
13.
14.
15.
16.
Standard length
Snout to origin of dorsal Fin
Snout to origin of pelvic fin
Snout to origin of anal fin
Length of base of anal fin
Distance between dorsal and adi-
pose dorsal fins
Greatest body depth
Depth of caudal peduncle
Length of medial mandibular
barbel
Length of pectoral fin
Length of pelvic fin
Head length
Interorbital width
Snout length
Orbital width
Length of postorbital portion of
head
Gape width
castaneus
Range
23.2-46.6
0.65-0.71
0.32-0.34
0.40-0.42
0.57-0.63
0.11-0.15
0.20-0.23
0.11-0.13
0.27-0.40
0.20-0.22
0.08-0.11
0.18-0.21
0.39-0.51
0.27-0.36
0.10-0.15
0.51-0.56
0.45-0.57
X
0.685
0.327
0.413
0.592
0.124
0.212
0.123
0.339
0.209
0.097
0.191
0.467
0.335
0.118
0.544
0.497
uruyensts
Paratypes
Range
36.5-43.1
0.54-0.57
0.37-0.40
0.46-0.51
0.47-0.52
0.16-0.19
0.18-0.22
0.12-0.14
0.19-0.25
0.18-0.20
0.09-0.11
0.20-0.22
0.50-0.58
0.39-0.46
0.09-0.13
0.48-0.55
0.52-0.60
X
0.559
0.375
0.482
0.491
0.174
0.193
0.128
0.223
0.186
0.105
0.213
0.542
0.423
0.113
0.510
0.571
Lectotype
56.8
0.62
0.36
0.43
0.58
0.20
0.23
0.12
0.36
0.21
0.12
0.21
0.47
0.41
0.11
0.48
0.53
marmoratus
Non-types
Range
19.7-73.0
0.52-0.71
0.31-0.42
0.37-0.50
0.49-0.61
0.09-0.21
0.16-0.26
0.09-0.15
0.16-0.47
0.16-0.23
0.08-0.13
0.17-0.24
0.41-0.56
0.31-0.45
0.07-0.14
0.43-0.63
0.44-0.67
X
0.644
0.355
0.438
0.547
0.134
0.206
0.120
0.310
0.202
0.111
0.205
0.486
0.356
0.112
0.537
0.552
Holotype
46.5
0.58
0.32
0.44
0.57
0.18
0.22
0.11
0.40
0.20
0.12
0.21
0.44
0.36
0.12
0.56
0.47
gouldingi
Paratypes
Range
27.0-46.0
0.57-0.60
0.30-0.33
0.42-0.44
0.54-0.57
0.16-0.19
0.15-0.20
0.10-0.13
0.38-0.43
0.20-0.22
0.10-0.12
0.20-0.22
0.46-0.50
0.36-0.40
0.10-0.14
0.54-0.63
0.53-0.58
X
0.576
0.318
0.433
0.552
0.178
0.182
0.118
0.407
0.204
0.112
0.210
0.468
0.382
0.123
0.556
0.561
of anal fin slightly convex anteriorly, straight posteriorly.
Pectoral fin with seven rays, reaching posteriorly to vertical
through insertion of fourth to sixth anal-fin ray. Anal-fin
margin straight anteriorly, rounded posteriorly. Anal-fin
rays 39 to 43 [43]. Caudal fin with 15 principal rays; eight
principal rays in lower lobe. Dorsal fin small, with five rays.
Small adipose fin present in all examined specimens.
Two rows of teeth on premaxilla, inner series smaller,
less evident. Lower jaw with a band of cardiform teeth,
outer row distinctly larger.
Anterior and posterior nares well separated, anterior
nares slightly tubular. Maxillary barbel extending poste-
riorly to beyond end of pectoral fin. Medial mandibular
barbel extending to or slightly beyond middle of pectoral
fin. Lateral mandibular barbel distinctly shorter than me-
dial.
Five vertebrae in anterior vertebral complex; free verte-
brae posterior to complex 38 (6) [38].
COLORATION.?Overall coloration dark brown, mottled;
head distinctly darker dorsally. Dark body pigmentation
NUMBER 442
TABLE 3.?Frequency distribution of numbers of anal-fin rays in Helogenes uruyensis, H. castaneus, H.
gouldingi, and major geographic subunits of //. marmoratus.
Species 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 N
H. gouldingi
H. castaneus
H. uruyensis
H. marmoratus
Guyana
Surinam
Venezuela
Brazil
Ecuador
Peru
1 2
5
1
1
6
4
1
1
8
8
10
1
2
1
3
10
10
1
8
5
1
10
5
2
3
9
12
4
5
4
-
6
7
2
3
1
-
5
8
1
_
1
2
2
jt
1
1
1
7
42
9
25
40
35
11
5
31
41.14
46.12
36.14
41.32
43.22
43.48
44.91
45.20
44.58
FIGURE 4.?Geographic distribution of Helogenes gouldingi (star), Helogenes castaneus (circle with enclosed
star indicates type-locality, solid circle indicates localities of other examined specimens), and Helogenes
uruyensis (triangle) (some symbols represent more than one collecting locality or lot of specimens).
extending onto basal one-third of caudal fin, posterior
margin of pigmentation band very distinct, with a straight
or slightly wavy border. Rayed dorsal fin mottled, darker
at base. Caudal fin dark basally, mottled over posterior two-
thirds. Anal fin dark brown at base, mottled distally, more
so along posterior portion. Pectoral and pelvic fins ranging
from mottled, particularly basally, to dark brown.
DISTRIBUTION.?Known only from the type-locality (Fig-
ure 4).
ECOLOGY.?The type series was collected in a small black-
water tributary of the Rio Madeira.
ETYMOLOGY.?Named for Michael Goulding, the collec-
tor of the type series, in recognition of his contributions to
increasing our knowledge of the Amazonian fish fauna.
MATERIAL EXAMINED.?8 specimens (7, 27.0-46.5).
Holotype: BRAZIL. Amazonas: Igarape 15 km from Hu-
maita along the Rio Madeira, (7?31'S, 63?02'W), collected
by Michael Goulding, 7 Aug 1984, MZUSP 28854, 1 (46.5).
Paratypes: 7 specimens, taken with holotype: MZUSP
28855, 3 (27.0-37.4); USNM 269446, 4 (25.8-46.0; one
specimen cleared and counterstained for cartilage and
bone).
Helogenes castaneus (Dahl), new combination
FIGURES 2, 4, 5
Leyvaichthys castaneus Dahl, 1960:303 (type-locality: Colombia: Rio Guaya-
bero].?Cala 1977:11 [Colombia: Rio Guayabero system].
Levaichthys castaneus.?Glodek and Carter, 1978:80 [distribution; generic
name misspelled].
10 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
FIGURE 5.?Helogenes castaneus, ANSP 128703, 46.6 mm SL; Rio Meta system, Colombia.
DIAGNOSIS.?Helogenes castaneus is readily distinguisha-
ble from H. uruyensis in the number of anal-fin rays (43 to
49 in contrast to 32 to 37) and a number of morphometric
differences (Table 2). The presence of eight principal rays
in the lower lobe of the caudal fin of//, castaneus separates
it from H. marmoratus, which has nine principal rays in the
lower lobe of that fin. The 43 to 49 anal-fin rays of Helogenes
castaneus discriminate that species from H. gouldingi, which
has 39 to 43 anal-fin rays. Those two species are also
separable in various morphometric characters, most notably
their relative snout lengths and in the distance between the
rayed and adipose dorsal fins (see "Key" and Figure 2).
DESCRIPTION.?Morphometrics of the examined speci-
mens are given in Table 2.
Dorsal profile of body smooth, slightly convex from snout
to dorsal portion of caudal peduncle. Ventral profile of
body smooth, convex from lower jaw to origin of pelvic
fins. Base of anal fin straight to slightly sigmoid. Pectoral
fin with seven rays, extending posteriorly to beyond anus,
to or beyond vertical through origin of anal fin. Pelvic fin
with six rays, reaching to vertical through insertion of third
anal-fin ray. Anal-fin margin straight or slightly convex
anteriorly, concave posteriorly. Anal-fin rays 43 to 49 [hol-
otype reported by Dahl as having 49 rays]. Rayed dorsal fin
small, with five rays. Adipose dorsal fin present in examined
specimens [reported as absent in holotype, not seen by us],
of variable size in some population samples. Caudal fin with
15 principal rays; eight principal rays on lower lobe.
Premaxilla with two series of teeth in juveniles, outer row
larger; inner row lacking in specimens larger than approx-
imately 47 mm SL. Lower jaw with a band of cardiform
teeth, outer series enlarged.
Anterior and posterior nares well separated, both some-
what tubular. Maxillary barbel extending posteriorly some-
what beyond vertical through insertion of pectoral fin.
Medial mandibular barbel extending posteriorly to vertical
through origin of anal fin. Lateral mandibular barbel
shorter, reaching approximately to vertical through middle
of pectoral fin.
Five vertebrae in anterior vertebral complex; vertebrae
posterior to complex 36 (4), 37 (9), 38 (5), 39 (1).
COLORATION.?Overall coloration of head and body
brown, somewhat mottled, dark body pigmentation extend-
ing onto basal one-third of caudal fin; a darker horizontal
band extending from rear of head, along and above lateral
line for approximately one-third of body length. A series of
very lightly pigmented spots located along lateral stripe;
spots larger anteriorly, reduced to narrow lines posteriorly.
Rayed dorsal fin mottled, darker basally. Adipose fin mot-
tled. Caudal fin with basal one-third dark brown, region of
dark pigmentation with a discrete posterior border; margin
straight or somewhat wavy. Anal fin mottled. Pectoral and
pelvic fins mottled, darker basally.
DISTRIBUTION.?Rio Guaviare and Rio Meta drainages
of the upper Rio Orinoco in eastern Colombia (Figure 4).
REMARKS.?Dahl's description of Leyvaichthys castaneus
(1960:303) was based on three specimens collected in the
region of the southern Serrania de la Macarena of Colombia
in the upper Rio Guayabero, a tributary of the Rio Guav-
iare, which is an affluent of the Rio Orinoco. We have been
unable to locate the type series of the species in any repo-
sitory, and Dr. P. Cala, who has also attempted to determine
the depositories of all of the types of the species described
by Dahl, has been similarly unsuccessful (P. Cala, personal
communication). We thus assume that the specimens are
lost.
The available material of the family Helogenidae from
Colombia was ail collected in the basin of the Rio Meta, the
major drainage basin immediately to the north of the Rio
Guaviare. These Colombian specimens differ from the de-
NUMBER 442 I I
scription of Leyvaichthys castaneus in several details. The
differences are, however, either intraspecifically variable in
other helogenid species, and their utility in delimiting spe-
cies within the Helogenidae thus questionable, or in the
case of a dentitional character are based on an apparently
erroneous observation by Dahl.
Dahl stated that the anal-fin ray count and relative dis-
tance from the tip of the snout to the dorsal-fin origin
separated Leyvaichthys from Helogenes. A re-examination
reveals that those characters fail to distinguish Helogenes
castaneus from other species of helogenids (see "Remarks"
under discussion of Helogenes) and thus are not useful in
defining Leyvaichthys relative to Helogenes. The three most
significant of the characters purportedly diagnostic for Ley-
vaichthys, or that require discussion, are the presence or
absence of the adipose dorsal fin, the number of branched
rays on the caudal fin, and the number of rows of teeth and
the form of dentition on the premaxilla.
Although Dahl (1960:302) states that Leyvaichthys casta-
neus "differs in so many characters from Helogenes
Guenther, that it has been considered necessary to describe
it as the type of a new genus . . . ," the only character that
he specifically cited in the diagnosis of the new genus as
differing from the condition in the previously known Helo-
genes was the lack of an adipose dorsal fin. The available
specimens of//, castaneus demonstrate noticeable variability
in the relative size of the adipose dorsal fin. Furthermore,
as discussed above (see "The Adipose Dorsal Fin in the
Helogenidae") the presence or absence of an adipose fin is
intraspecifically variable among helogenids and of is ques-
tionable validity as the basis for discriminating taxa at the
specific, let alone generic levels, particularly in the absence
of other correlated differences. In light of the variability in
the presence of the adipose fin in Helogenes marmoratus, and
given the range in the relative size of that structure in
examined Colombian helogenids, we assume that the ab-
sence of the adipose fin in the type series of Leyvaichthys
castaneus represents intraspecific variation.
Dahl (1960:304) described Leyvaichthys as having "10
branched rays in the upper and 12 in the lower lobe" of the
caudal fin. Such a high branched caudal fin count is un-
known in any catfish (see Lundberg and Baskin, 1969:35,
for a summary) and differs significantly from the six rays in
the upper lobe of the fin and seven or eight in the lower
lobe found in examined material of the Helogenidae. Al-
though the specimens herein identified as Helogenes casta-
neus have six branched rays in the upper and seven
branched rays in the lower lobe of the caudal fin, they also
have four externally visible unbranched rays in the upper
lobe of the fin and five in the lower lobe of the fin. The
addition of the unbranched rays to the branched ray count
would bring the total number of caudal rays, branched and
unbranched, to the 10 plus 12 count cited by Dahl. Given
the unlikely nature of the number of branched rays cited
by Dahl and the equivalence between the count of total
externally visible caudal rays and the figures he presented,
Dahl obviously included the externally visible unbranched
rays in his count of branched caudal-fin rays.
Dahl (1960:303) stated that Leyvaichthys castaneus was
characterized by a single row of teeth on the premaxillary.
Helogenes, in contrast, has two series on that element, al-
though Dahl did not cite that difference. As discussed
previously (see "Remarks" under discussion of Helogenes),
the number of tooth rows in specimens herein considered
to be Helogenes castaneus are ontogenetically variable, with
two rows present in juveniles and only one in adults. An-
other dentitional character cited by Dahl as characteristic
of Leyvaichthys, the serrations on the premaxillary teeth, is
evidently otherwise unknown in catfishes and has not been
encountered in the examined material of the family. As a
consequence its cited presence in Leyvaichthys is presumed
erroneous.
In the absence of the type series of Leyvaichthys castaneus,
it is not possible to definitely determine whether our sup-
position about tooth serrations and adipose fin absence is
correct. We prefer to identify the Colombian helogenid
material we have examined as Helogenes castaneus. This
decision is based on circumstantial evidence from several
systems. If the caudal-fin ray count cited by Dahl does
represent the total number of externally visible rays in the
caudal fin, then his specimens of Leyvaichthys castaneus had
eight principal rays in the lower lobe of the caudal fin (seven
branched and one unbranched rays). Such a ray count
occurs in H. gouldingi and the specimens herein considered
as H. castaneus, but excludes H. marmoratus and H. uruyen-
sis, which have an additional branched ray in the lower lobe
of the caudal fin. The examined Colombian material comes
from a region proximate to the type-locality of Leyvaichthys
castaneus, with both being within the Rio Orinoco drainage
system. Helogenes gouldingi, the second species with eight
lower lobe principal caudal rays, in contrast, is known only
from the middle Rio Madeira system in the Amazon basin.
More significantly Leyvaichthys castaneus was described by
Dahl (1960:309) as having a total of 45 to 49 anal-fin rays,
a count in agreement with the 43 to 49 anal-fin rays found
in our material, but distinct from the 39 to 43 rays found
in Helogenes gouldingi. Finally, the larger of the Colombian
specimens we have examined are unique among examined
helogenids in having only a single series of teeth in the
upper jaw, a character noted by Dahl as distinguishing for
Leyvaichthys (= Helogenes) castaneus. Thus, the material we
identify as Helogenes castaneus best fits the original descrip-
tion of the species among examined specimens.
Hopefully further collections can eventually be made in
the type-locality to determine whether our assumptions
about variability in the presence of the adipose fin and on
tooth form are correct. The conservative course of action
in which we equate, for the present, the available specimens
12 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
from the Colombian portions of the Orinoco basin with
Leyvaichthys (= Helogenes) castaneus is preferable to the de-
scription of a new and most likely invalid species for these
distinctive specimens.
MATERIAL EXAMINED.?47 specimens (25, 23.2-46.6
mm SL).
COLOMBIA. Meta: Cano Angosturas, Hacienda Humacita
(03?58.5'N, 73?4.5'W), ANSP 128702, 1 (39.9). Cano
Enma, Finca El Viento, 33.5 km NE of Puerto Lopez
(04?08'N, 72?39'W), ANSP 128703, 2 (43.3-46.6). Cano
El Viento, Finca El Viento (04?08'N, 72?39'W), ANSP
128704, 1 (41.6). Quebrada La Venturosa, between La
Balsa and Puerto Lopez (04?05'N, 72?58'W), ANSP
128705, 1 (36.4). Tributary to Rio Yucao, approximately
4.7 km W of Puerto Gaitan, UF 33472, 41 (20, 23.2-38.8).
Rio Yucao, on dirt road paralleling Rio Meta, UF 33565,
1.
Helogenes uruyensis Fernandez-Yepez, new status
FIGURES 4, 6
Helogenes marmoratus uruyensis Fernandez-Yepez, 1967:166, pi. 2, pi. 3:
fig. 2, table 2 [type-locality: Venezuela: Guayana, Rio Uruyen near
Auyantepui].?Mago-Leccia, 1970:82 [citation].?Glodek and Carter,
1978:76 [in key).
DIAGNOSIS.?Helogenes uruyensis, the most distinctive spe-
cies in the family, can be distinguished from all other
helogenids in having 32 to 37 anal-fin rays in contrast to 39
to 49 in the remainder of the family. The possession of 15
principal caudal fin rays, with eight principal rays on the
lower lobe of the caudal fin, further distinguishes the species
from H. gouldingi and H. castaneus, which have nine prin-
cipal rays on the lower lobe of the fin and a total of 16
principal rays. Helogenes uruyensis is also separable from H.
castaneus and H. gouldingi by a series of morphometric
characters (see Table 2).
DESCRIPTION.?Morphometrics of the paratypes are
given in Table 2.
Dorsal profile of body smooth, slightly convex from snout
to dorsal portion of caudal peduncle. Ventral profile of
body slightly convex from lower jaw to anus. Base of anal
fin straight. Pectoral fin with seven rays, reaching to or
falling slightly short of vertical through insertion of pelvic
fin. Pelvic fin with six rays, reaching to vertical through
insertion of second or third anal-fin rays. Anal-fin margin
slightly convex anteriorly, concave posteriorly. Anal-fin rays
32 to 37. Rayed dorsal fin small, with five rays. Adipose
dorsal fin present in all specimens examined.
Premaxilla with two rows of teeth, inner smaller, largely
covered by fleshy lining of mouth. Lower jaw with a cardi-
form band of teeth, outer row enlarged.
Anterior and posterior nares well separated, anterior
tubular. Maxillary barbel extending posteriorly to slightly
beyond vertical through insertion of pectoral fin. Medial
and lateral mandibular barbels of same length or medial
barbel slightly longer; medial barbel extending posteriorly
to vertical through line approximately two-thirds along
length of pectoral fin.
Five vertebrae in anterior vertebral complex; free verte-
brae posterior to complex 38 (1), 39 (6).
COLORATION.?Overall coloration of head and body
brown, somewhat mottled. Dorsal portions of head and
nape somewhat darker. A series of unpigmented spots along
lateral line; spots more numerous anteriorly, nearly contig-
uous in that region. Dark body pigmentation extending
onto anterior one-third of caudal fin rays; posterior border
of dark pigmentation on caudal fin discrete, with somewhat
irregular margin.
Rayed dorsal fin mottled, somewhat darker basally. Adi-
pose fin mottled, with hyaline border. Caudal fin dark on
basal one-third, mottled on posterior two-thirds, borders
hyaline. Anal fin dark brown on fleshy basal portion, mot-
FICURE 6.?Helogenes uruyensis, paratype, USNM 219598, 43.1 mm SL; Rio Uruyen, Venezuela.
NUMBER 442 13
tied along medial one-third, distal one-third of fin hyaline.
Pectoral and pelvic fins mottled basally, hyaline distally.
DISTRIBUTION.?Known only from the type-locality, the
Rio Uruyen, which flows from the southeast of Auyantepui
in Guayana, Venezuela (Figure 4). The Rio Uruyen is part
of the Rio Caroni system, a southern tributary of the Rio
Orinoco. The map in Glodek and Carter (1978, fig. 2)
incorrectly indicates the locality as being in the Rio Cuyuni
system, a tributary of the Essequibo River.
REMARKS.?The original type series of Helogenes uruyen-
sis consisted of the holotype and nine paratypes divided
between the personal collection of Augustin Fernandez-
Yepez and MBUCV. Portions of Fernandez-Yepez's per-
sonal collection were later transferred to the Ministerio de
Agricultura y Cria (MAC) and subsequently to MBUCV.
Although all paratypes are accounted for (see "Material
Examined"), the holotype, a 49.5 mm SL specimen origi-
nally deposited in the personal collection (AFY 56613), was
not located in the MBUCV holdings.
Fernandez-Yepez in his description of Helogenes uruyensis
recognized it as a subspecies of H. marmoratus Giinther.
Helogenes marmoratus uruyensis was distinguished by Fernan-
dez-Yepez (1967:170) from H. marmoratus marmoratus by
differences in the length of the maxillary and mandibular
barbels, anal-fin base length and anal-fin ray count. Al-
though the two forms actually overlap in the lengths of the
medial mandibular barbel (Table 2), lateral mandibular and
maxillary barbels, and anal-fin base (Table 2), they do differ
in anal-fin ray counts (Table 3). Fernandez-Yepez's recog-
nition of his form as a subspecies rather than as a species
was evidently a consequence of what he thought to be close
similarity in anal-fin ray counts in the two forms (anal-fin
rays reported by Fernandez-Yepez as being 37 to 41 in H.
marmoratus marmoratus and 31 to 36 in H. marmoratus
uruyensis). Results of this study have shown that H. marmor-
atus has rather 39 to 48 anal-fin rays. The distinctly lower
count for that species reported by Fernandez-Yepez appears
to have been based on Eigenmann (1912:208), who listed
his material from the Essequibo system as having 37 to 40
anal-fin rays, perhaps as a consequence of his failure to
detect the very small anterior two rays. Re-examination of
portions of Eigenmann's material along with other material
from Guyana has failed to reveal any specimens of H.
marmoratus with less that 39 anal-fin rays. Given the gap in
anal-fin ray counts between Fernandez-Yepez's Helogenes
marmoratus uruyensis (32 to 37 based on our examination)
and Helogenes marmoratus (39 to 48), we recognize the
former as a distinct species, Helogenes uruyensis.
MATERIAL EXAMINED.?9 specimens (7, 36.5-43.1 mm
SL).
VENEZUELA. Bolivar: Rio Uruyen, south side of Auyante-
pui, USNM 219598, 1 (43.1, paratype of Helogenes marmor-
atus uruyensis Fernandez-Yepez; formerly MBUCV V-2615,
in part); MBUCV V-2615, 3 (36.65-40.0, paratypes of H.
m. uruyensis); MBUCV V-10852, 5 (3, 36.5-39.6, paratypes
of//, m. uruyensis, formerly MAC 56028 and AFY 56614;
anal-ray counts, but no other data taken from 2 other
specimens.
Helogenes marmoratus Giinther
FIGURES 7-9
Helogenes marmoratus Giinther, 1863:443 [type-locality: Guiana (= Guy-
ana)]; 1864:66 [expansion of species description, British Guiana (= Guy-
ana): Essequibo River].?Eigenmann and Eigenmann, 1888:120 [cita-
tion]; 1890:312 [description based on Gunther, 1864]; 1891:35 [cita-
tion].?Eigenmann, 1910:398 [citation]; 1912:207, pi. 22: fig. 2 [desig-
nation as type of family Helogeneidae (= Helogenidae); British Guiana
(= Guyana): Aruataima, Holmia, Potaro Highland, Tukeit Landing].?
Steindachner, 1915:86, pi. 11: fig. 6 [Brazil: Para, Santarem, Rio Branco
at Conceicao; Surinam: Albina].?Fowler, 1915:228 [British Guiana:
Holmia].?Jordan, 1923:150 [citation].?Gosline, 1945:53 [citation].?
Van der Stigchel, 1947:109 [British Guiana: Holmia].?Fowler, 1954:4
[literature compilation].?Hoedeman, 1952:X.30.31.76:1-2, fig. [pop-
ular account].?Boeseman, 1952:182 [Surinam: Bush Creek, Coppen-
ame River]; 1953:9 [Surinam: Nassau Mountains, Morawini Basin, Zan-
derij].?Hoedeman, 1953:253 [photo; aquarium notes]; 1954:244-245,
fig. 180 [popular account].?Boeseman, 1954:20 [Surinam: Para-
maribo].?Hoedeman, 1959:244-245 [popular account]; 1968:141-142
[popular account].?McAllister, 1968:76 [branchiostegal rays].?Char-
don, 1968:152 [Weberian Apparatus morphology].?Lundberg and Bas-
kin, 1969:14, 17, 41, fig. 7, table 1 [caudal skeleton anatomy].?Hoede-
man, 1974:388 [aquarium care, behavior].?Lundberg, 1975:70 [cranial
morphology].?Glodek and Carter, 1978:76, 79 [in key, distribution].?
Mees, 1983:56 [French Guiana: Mena River, Crique St. Anne; Crique
Vampire; comments on species distribution].?Ortega and Vari, 1986:16
[Peru: Amazon basin].
Helogenes amazonae Delsman, 1941:80 [type-locality: Brazil: Manaos (=
Manaus)].?Glodek and Carter, 1978:77, 80 [in key, distribution]. [New
synonymy.]
Helogenes unidorsalis Glodek and Carter, 1978:75, fig. 1 [type-locality:
Ecuador, Rio Bobonaza between Sarayacu and Montalvo]. [New synon-
ymy.]
DIAGNOSIS.?The possession of nine principal fin rays in
the lower lobe of the caudal fin of Helogenes marmoratus
distinguishes the species from H. gouldingi and H. castaneus,
which have eight principal rays on the lower lobe of that
fin. The 39 to 48 anal-fin rays of H. marmoratus separates
that species from H. uruyensis, which has 32 to 37 anal-fin
rays.
DESCRIPTION.?Morphometrics of the lectotype and
measured non-type specimens given in Table 2.
Dorsal profile of body smooth, slightly convex from snout
to dorsal portion of caudal peduncle. Ventral profile of
body slightly convex from lower jaw to anus. Base of anal
fin straight or very slightly sigmoid. Pectoral fin with seven
rays, reaching beyond vertical through insertion of pelvic
fin, sometimes to vertical through origin of anal fin. Pelvic
fin with six rays, reaching posteriorly to region bordered
by vertical through origin of anal fin and vertical through
insertion of fourth anal ray. Anal-fin margin straight or
slightly convex anteriorly, concave posteriorly. Anal-fin rays
40 to 48 [41] (see Table 3 relative to geographic variation).
Rayed dorsal fin small, with five rays. Adipose dorsal fin
14 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
FIGURE 7.?Helogems marmoratus, USNM 273057, 63.7 mm SL; Potaro River, Guyana.
FIGURE 8.?Helogenet marmoratus, USNM 264030, 62.3 mm SL; Rio Tambopata, Peru.
present or absent [present in lectotype], when present dem-
onstrating differing degrees of relative development.
Premaxilla with two rows of teeth, inner series smaller,
sometimes difficult to locate in fleshy lining of mouth.
Lower jaw with a cardiform band of teeth, outer row
enlarged.
Anterior and posterior nares well separated, tubular.
Maxillary barbel of variable length, typically extending
posteriorly to beyond vertical through pectoral fin inser-
tion. Medial mandibular barbel longer than lateral, devel-
oped to different degrees, extending posteriorly to region
bordered by vertical through posterior of head and vertical
through origin of anal fin.
Five vertebrae in anterior vertebral complex; free verte-
brae posterior to complex 36 (5), 37 (26), 38 (61), 39 (24),
40 (2).
COLORATION.?Overall pigmentation of head and body
dark, mottled to different degrees. Some individuals with
horizontal stripe of darker pigmentation extending from
rear of head along lateral line; stripe extending up to one-
third distance along lateral line. Rotund or horizontally
elongate spots of light pigmentation distributed along lat-
eral line, particularly on anterior portion of body where
they are nearly contiguous. Specimens from Essequibo
River with uniform dark pigmentation along middorsal
portion of body and proximate regions. Individuals from
other portions of species range with a variably intense dark
middorsal stripe that extends from rear of head to insertion
of dorsal fin. Middorsal stripe paralleled on each side by
stripe that extends from head to meet its counterpart prox-
imate to adipose fin. Dark body pigmentation extending
onto base of caudal fin, posterior margin of dark coloration
discrete; border ranging from straight to wavy.
Pectoral fin mottled in juveniles, particularly basally;
NUMBER 442 15
FIGURE 9.?Geographic distribution of Helogenes marmoratus (solid circles indicate localities of material
examined; stars indicate literature records; some symbols represent more than one collecting locality or lot
of specimens).
more uniformly pigmented in adults, often dark brown.
Anal fin dark basally in juveniles, mottled distally; more
uniformly dark in adults. Anal-fin margin hyaline in speci-
mens from Guianas and upper Rio Orinoco, pigmented in
individuals from Amazon, with a thin darker line of differ-
ing degrees of intensity paralleling distal margin of fin
approximately one-fifth of distance from fin margin. Rayed
dorsal fin dark basally in juveniles, uniformly dark in adults,
sometimes with tip or margin hyaline. Adipose fin mottled
in smaller individuals, dark in larger specimens. Caudal fin
dark on basal one-third, mottled on posterior portion; de-
gree of posterior mottling and extent of development of
pigmentation correlated with overall intensity of body co-
loration.
DISTRIBUTION.?Atlantic drainages of Guyana, Surinam,
and French Guiana, upper Rio Orinoco and Rio Negro
systems in Venezuela, Amazon basin in Brazil, Peru, and
Ecuador (Figure 9).
ECOLOGY.?Collections of Helogenes marmoratus in the
Corantijn River system of Surinam, tributaries of the upper
Rio Orinoco and upper Rio Negro in Venezuela, and in the
Rio Tambopata of the Rio Madeira system in southeastern
Peru indicate that the species is typically an inhabitant of
black or clear waters, usually in forest streams with moder-
ate to swift current flow over firm sand or gravel bottoms.
The only exception, one sample from Surinam (USNM
226152), was taken in an artificially impounded black water
pond with slow current. In rain-forest streams under more
open canopy, with a resultant greater degree of light pen-
etration, Helogenes marmoratus is typically found in clumps
of aquatic vegetation, whereas in well-shaded sites lacking
submerged or emergent aquatic vegetation, it has been
collected in leaf litter and debris.
Examination of the stomach contents of specimens from
Peru, Venezuela, and Surinam has shown that the species
feeds evidently exclusively on allochthonus terrestrial in-
sects, particularly ants, which presumably are blown or fall
onto the water surface.
VARIATION.?Helogenes marmoratus is the most geo-
graphically wide-ranging species recognized in this study,
with examined specimens originating in the vast expanse
from the Atlantic drainages of the Guianas to the upper
Rio Orinoco, to a number of localities along the main stream
of the Amazon and some of its major tributaries, including
the Rio Madeira, Rio Tapajos, Rio Negro, Rio Ucayali, and
Rio Marafton systems (Figure 9). These relatively small
fishes evidently live in discrete populations that are appar-
ently limited to smaller tributaries.
The species shows a significant amount of meristic, mor-
phometric, and coloration variability across its range, a
situation that is to be expected given the broad geographic
expanse involved and apparently somewhat disjunct distri-
bution of the species in black or clearwater tributary streams
rather than main rivers and Whitewaters. The degree of
intraspecific morphometric variability in H. marmoratus is
pronounced (Table 2), with the ranges of the relative dis-
tances from the snout to the dorsal-fin origin and between
the rayed and adipose dorsal fins being notably broad.
16 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
However, these proportions show significant overlap when
samples of the species from different areas are compared,
and as such they do not serve to subdivide the species into
less-inclusive subunits. Neither are any geographical clinal
patterns obvious in these characters.
Among meristic characters, only the principal caudal-fin
ray count, the number of vertebrae, and the anal-fin ray
count show variability within the family. The first of these,
the principal caudal-fin ray count, is constant within Helo-
genes marmoratus. Although that species shows variability in
the number of vertebrae, the modal count for each popu-
lation of the species is either 38 or 39, with large scale
overlap in the ranges of the values for members of each
population. That character does not show any recognizable
geographic pattern within the available material of//, mar-
moratus. Anal-fin ray counts do show a distinct pattern
(Table 3) although they do not serve to discretely subdivide
the species. Specimens of H. marmoratus from the type
region, the Essequibo River, have the lowest average num-
ber of rays (41.32). Individuals from Surinam and the
Orinoco basin in Venezuela have higher average anal-fin
ray counts (43.22 and 43.48 respectively). Those popula-
tions also have a greater range of anal-fin rays and higher
maximum anal-fin ray counts. Specimens from the Rio
Amazonas basin have yet higher average anal-fin ray counts
(43.58-45.20) and further increases in the value of the
lowest anal-fin ray count, most notably in the Ecuadorian
and Peruvian samples.
As noted in the description of coloration, there is geo-
graphic variability in pigmentation along the dorsal surface
of the body and on the anal fin. The form of the border
between the hyaline or mottled posterior portion of the
caudal fin and the dark pigmentation that extends from the
body onto the base of the fin also varies somewhat. A
straight demarcation is most common in the Guianas, but
that border is typically extremely wavy in specimens from
the upper Rio Orinoco. However, some individuals from
the Guianas have irregular borders, and nearly straight
borders are found in a few specimens from the Rio Orinoco
system. Although some of the pigmention differences ap-
pear to be geographically consistent and may delimit sub-
units of the species, we prefer not to recognize those group-
ings formally until more geographically inclusive collections
of the species are available for further analysis.
REMARKS.?The original description of Helogenes mar-
moratus (Giinther, 1863:443) was based on two specimens
from the Essequibo River. One of these specimens was
borrowed some years ago by another worker, but not re-
turned, and must be presumed lost. The remaining individ-
ual (BMNH 1864.1.21:83, 56.8 mm SL) is designated
herein as the lectotype of the species.
As discussed above, Helogenes marmoratus demonstrates
variability both in the presence or absence of an adipose
dorsal fin, and in the size of that fin when present. Refer-
ence to the description of Helogenes unidorsalis by Glodek
and Carter (1978:77) and the accompanying key shows that
the primary basis for the recognition of the species was the
absence of the relatively small adipose fin, an uncertain
character by which to delimit a species in light of the
intrapopulational variability of the development of that
structure in various species in the Ostariophysi.
The two other characters cited in Glodek and Carter's
diagnosis of Helogenes unidorsalis are the possession by the
species of 37 to 44 anal-fin rays and the presence of dark
pigmentation on the pectoral fins. Another evidently diag-
nostic character for the species not commented on by those
authors was their report of only six rays in the pectoral fin
rather than the seven typical for helogenids. Examination
of the available specimens of the type series of//, unidorsalis
(FMNH 80463, 80464) has shown that there are rather 44
to 48 anal-fin rays in those individuals, a count that falls
within the range of H. marmoratus (Table 3). Similarly the
type series has a constant value of seven pectoral-fin rays in
agreement with other helogenids and with the number of
rays shown in the illustration of the holotype (Glodek and
Carter, 1978, fig. 1). The degree of pectoral-fin pigmenta-
tion increases ontogenetically in all of the recognized helo-
genid species. Material of//, marmoratus from the Essequibo
River, the type region for the species, has pectoral fins that
range from hyaline with limited mottling in smaller speci-
mens, through individuals with some pectoral fin pigmen-
tation (e.g., Eigenmann, 1912, pi. 22: fig. 3), to larger fish
that have dark fins such as those reported for H. unidorsalis.
The specimens of H. unidorsalis are relatively large (59.4-
73.0 mm SL) and appear to have been poorly preserved,
with a consequent loss of pigmentation on the body, making
the pectoral-fin coloration even more obvious. In light of
the intrapopulational ontogenetic variability of the charac-
ter, the large size of the specimens, and the presence of
darkly pigmented pectoral fins in other helogenids, partic-
ularly larger individuals, that pigmentation character is not
considered useful in delimiting H. unidorsalis.
None of the characters cited in the original description
of Helogenes unidorsalis distinguish that species from //.
marmoratus. Neither have differences between the nominal
forms in other examined features been discovered during
this study. As a consequence H. unidorsalis is herein consid-
ered a synonym of//, marmoratus.
Delsman, in his brief original description of Helogenes
amazonae (1941:80), cited differences in anal-fin ray counts,
pectoral-fin length, and the location of the abrupt terminus
of the dark pigmentation that extends from the body onto
the base of the caudal fin as separating his nominal form
and H. marmoratus of Giinther. Helogenes marmoratus was
listed by Delsman as having 37 to 40 anal-fin rays contrary
to the 45 of H. amazonae. The low anal-fin ray count cited
for H. marmoratus was evidently taken from Eigenmann
(1912:208), a publication Delsman cited relative to the
NUMBER 442 17
perceived differences in pigmentation. Examination of por-
tions of Eigenmann's material along with other specimens
from the Guianas has failed to reveal any H. marmoratus
with fewer than 39 anal-fin rays. Giinther, in his original
description of the species, indicated that his material had
42 rays, and Steindachner (1915:87) lists 41 to 46 rays for
Surinamese and Brazilian specimens of the species. Material
examined during this study has 39 to 48 anal-fin rays, a
range bracketing the count of 45 in the holotype of H.
amazonae. The length of the pectoral fin and the position
of the posterior termination of the dark pigmentation on
the basal portion of the caudal fin in H. amazonae have
similarly been found to fall within the ranges of those
characters for H. marmoratus. None of the characters orgin-
ally cited as separating H. amazonae from H. marmoratus
distinguish the forms. Neither have any other features been
found during this study to delimit the nominal species.
Helogenes amazonae is consequently considered a synonym
off/, marmoratus.
Glodek and Carter (1978:81) raised the question of
whether the main stream of the Amazon might "act as a
barrier to the dispersal of these fishes" (helogenids) to the
southern portions of the Amazon basin. More recently Mees
(1983:57) noted that because Steindachner (1915:86) had
previously cited Helogenes marmoratus from Para and San-
tarem along the southern banks of the Brazilian Amazon,
such a hypothesis was invalid. We have also examined
specimens captured in the Rio Cururu, a tributary of the
Rio Tapajos, and have collected several series of individuals
in the upper Rio Madeira system in southeastern Peru
(Figure 9), with both areas being well south of the main Rio
Amazonas. A second species (H. gouldingi), described in this
paper from the middle Rio Madiera system, also occurs
distinctly south of the main portion of the Rio Amazonas
(Figure 4).
Material we examined of Helogenes marmoratus originated
from the Atlantic drainages of Guyana, Surinam, and
French Guiana, the Rio Tapajos, Para, Santarem, and vicin-
ity of Manaus in Brazil, northeastern and southeastern Peru,
eastern Ecuador, and both the upper Rio Orinoco and
upper Rio Negro in Venezuela. Within Brazil H. marmoratus
was also reported by Steindachner (1915:86) from the Rio
Branco near Conceicao (Figure 9).
MATERIAL EXAMINED.?312 specimens (99, 19.75-73.0
mm SL).
BRAZIL. Amazonas: Manaus, BMNH 1913.3.6:28-29, 1
(39.65); IRSNB 545, 1 (58.15, holotype of Helogenes ama-
zonae Delsman). Manaus, Reserve Ducke, IRSNB 19647, 1
(61.5). Turbinengraben, FMNH 70206, 1 (19.75; locality
uncertain). Para: Mission, Rio Cururu (probably mission
franciscaire du Cururu, cited by Collette, 1982:737),
FMNH 70114, 1 (33.7); FMNH 70115, 6 (4, 36.3-45.2).
Santarem, NMW 46356, 7; NMW 46357, 1. Santarem,
Uruara "brook" into Rio Amazonas, CAS 45776, 2 (30.65-
31.2). Lema, Rio Bern Fica (site could not located), NMW
46353, 14; NMW 46355, 1.
ECUADOR. Pastaza: Rio Bobonaza, between Sarayacu and
Montalvo, FMNH 80463, 1 (73.0, holotype of Helogenes
unidorsalis Glodek and Carter); FMNH 80464, 4 (59.4-
67.4, paratypes of//, unidorsalis; two of original six para-
types were not available for examination).
PERU. Madre de Dios: Reserva Natural de Tambopata,
between Rio Tambopata and Rio La Torre, small forest
stream draining into Rio Tambopata, USNM 264030, 19
(39.3-62.3); USM 1595, 4 (42.6-56.8); USM 1596, 5
(31.25-64.5). Loreto: Rio Ucayali basin, forest stream at
right bank of Rio Carahuayte, about 35 km SE of Jenaro
Herrera (04?55'S, 73?40'W), ZMA 116.987, 3. Rio Ucay-
ali basin, affluent of Rio Copal, 15 km from Jenaro Herrera
on road to Colonia Angamos (04?55'S, 73?40'W), ZMA
116.979,1.
GUYANA. Essequibo River, BMNH 1864.1.21:83, 1 (56.8,
lectotype of Helogenes marmoratus Giinther). Essequibo: Hol-
mia, AMNH 7113, 2 (49.4-57.45). Upper Potaro River,
Aruataima Falls, AMNH 27690, 1 (55.1); NMW 46359, 1.
Upper Potaro River, AMNH 27689, 2 (36.75-55.75);
USNM 273057, 10 (8, 21.0-63.7); ZMA 110.718, 1;
BMNH 1911.10.31:99-101, 2; NMW 46354, 1. Potaro
River, Kaieteur, BMNH 1972.10.17:693-732, 37. George-
town, Kurupung River, AMNH 8224, 1 (32.4). Essequibo
River, Morabelli, above Bartica, BMNH 1972.10.17:753-
804, 19(7,25.0-71.5).
SURINAM. No exact locality, NMW 46358, 2. Nickerie
District: Stream entering Corantijn River 2 km downstream
of Cow Falls, USNM 226149, 4 (25.45-47.1). Stream drain-
ing into Corantijn River at Mataway, USNM 226150, 7 (6,
21.7-63.0). Ramp Creek where crossed by road to Lucie
River, USNM 226151, 1 (39.25). Stream at Kamp Infras-
tructure, USNM 226152, 4 (2, 35.45-39.0). Stream drain-
ing into Kabalebo River near Kamp Anjoemara, USNM
226153, 4 (22.7-61.7). Tributary to Sisa Kreek down-
stream of where Sisa Kreek is crossed by road to Lucie
River, USNM 226154, 1 (32.1). Stream draining into Nick-
erie River, 12.5 km SW of Stondansie Falls, ZMA 105.828,
1. Para District: Carolina Kreek, approximately 10 km SE
of Zanderij, ZMA 106.531, 68. Saramaca District: Tributary
to Saramaca River (03?52'W, 56?55'W), ZMA 106.538,
1. Brokopondo District: Tapoeripa Kreek near Hermansdorp,
ZMA 106.532, 3. Tapoeripa Kreek, approximately 5 km
from Bronsweg, ZMA 106.533, 2. Tapoeripa Kreek near
Brokopondo, ZMA 106.534, 3. Dabikwen Kreek, approxi-
mately 5 km from Afobaka, ZMA 106.535, 2. Marowijne
District: Maka Kreek, 10 km S of Stoelmans Island, ZMA
106.536, 3. Stream draining into Morawijne River 36 km
N of Stoelmans Island, ZMA 106.537, 3.
FRENCH GUIANA. Cayenne: Oyapock River basin, Yawapa
Creek near Trois Sauts (02?15'N, 52?53'W), ZMA
107.824, 1. Crique Balate, affluent to lower Maroni River,
18 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
10 km SSE of St. Laurent (05?26'N, 54?02'W), ZMA
116.893, 10.
VENEZUELA. Territorio Federal Amazonas: Pozo de Lucas,
tributary of Rio Orinoco, 7 km from San Fernando de
Atabapo, MBUCV V-12989, 4 (32.1-58.4). Upper Rio
Orinoco, Burned Mountain Creek (in vicinity of Mount
Duida, see LaMonte 1929:1), AMNH 9626, 3 (47.9-60.7).
Stream draining into Rio Orinoco, where crossed by high-
way from Puerto Ayacucho to Samariapo, 25 km S of Puerto
Ayacucho, USNM 269975, 14 (10, 24.7-43.3). Park along
road from Puerto Ayacucho to Samariapo, 3 km S of Puerto
Ayacucho, FMNH 83867, 4. Stream 32 km S of Puerto
Ayacucho where crossed by road from Puerto Ayacucho to
Samariapo, FMNH 83868, 13 (2 specimens cleared and
stained). Rio Mawarinuma, 5 km above Cerro de la Neblina
base camp (0?55'N, 66? 10'W), AMNH 56096, 1.
Literature Cited
Berg, L.S.
1940. Classification of Fishes both Recent and Fossil. Travaux de Vln-
stitute Zoologique de I'Academie des Sciences de I'URSS, 5:87-517.
[Reprinted in English, 1965, Bangkok: Applied Scientific Re-
search Corporation of Thailand.]
Benin, L., and C. Arambourg
1958. Supra-ordre des Teleosteens. In P. Grasse, Traiti de zoologie,
13(3):2204-2500. Paris: Masson et C" Editeurs.
Boeseman, M.
1952. A Preliminary List of Surinam Fishes Not Included in Eigen-
mann's Enumeration of 1912. Zoologische Mededelingen,
31(7): 179-200.
1953. Scientific Results of the Surinam Expedition, 1948-1949, Part
II: Zoology, No. 2: The Fishes (I). Zoologische Mededelingen,
32(l):l-24.
1954. On a Small Collection of Surinam Fishes. Zoologische Mededelin-
gen, 33(3): 17-24.
Cala, P.
1977. Los peces de la Orinoquia Colombiana: Lista preliminar anotada.
Loiania (Acta Zoologica Colombiana), 24:1-21.
Chardon, M.
1968. Anatomie comparee de I'appareil de Weber et des structures
connexes chez les Siluriformes. Annales Musee Royal de I'Afrique
Central, Sciences Zoologiques, 169:1-277.
Collette, B.B.
1982. South American Freshwater Needlefishes of the Genus Potamor-
rhaphis (Beloniformes: Belonidae). Proceedings of the Biological
Society of Washington, 95(4):714-717.
Dahl, G.
1960. Nematognathus Fishes Collected during the Macarena Expedi-
tion, 1959, Part I. Novedades Colombianas, l(5):302-317.
Delsman, H.C.
1941. Resultats scientifiques des Crosieres du Navire-ecole Beige "Mer-
cator," III: Pisces. Memoires du Musee Royal d'Histoire Naturelle
de Belgique, series 2, 31:47-82.
Eigenmann, C.H.
1910. Catalogue of the Fresh-water Fishes of Tropical and South Tem-
perate America. In Reports of the Princeton University Expeditions
to Patagonia, 1896-1899, 3(4):375-511.
1912. The Freshwater Fishes of British Guiana, Including a Study of
the Ecological Grouping of Species and the Relation of the Fauna
of the Plateau to That of the Lowlands. Memoirs of the Carnegie
Museum, 5:1-578.
Eigenmann, C.H., and R.S. Eigenmann
1888. Preliminary Notes of South American Nematognathi. Proceedings
of the California Academy of Sciences, series 2, 1(2):119-172.
1890. A Revision of the South American Nematognathi or Cat-fishes.
Occasional Papers of the California Academy of Sciences, 1:1 -509.
1891. A Catalogue of the Fresh-water Fishes of South America. Pro-
ceedings of the United States National Museum, 14:1-81.
Fernandez-Yepez, A.
1967. Resultados zoologicos de la expedicion de la Universidad Central
de Venezuela a la region del Auyantepui en la Guayana Vene-
zolana, Abril de 1956, 6: Primera contribucion al conocimiento
de los peces, con description de dos especies y una subespecie
nuevas. Acta Biologica Venezuelica, 5(10): 159-177.
Fink, S.V., and W.L. Fink
1981. Interrelationships of the Ostariophysan Fishes (Teleostei). Zoo-
logical journal of the Linnean Society, 72(4):297-353.
Fowler, H.W.
1915. Notes on Netnatognathos Fishes. Proceedings of the Philadelphia
Academy of Sciences, 67:203-243.
1940. A Collection of Fishes Obtained by Mr. William C. Morrow in
the Ucayali River, Peru. Proceedings of the Academy of Natural
Sciences of Philadelphia, 91:219-289.
1954. Os peixes de agua doce do Brasil (4.a entrega). Arquivos de
Zoologia do Estado de Sao Paulo, 9:1-400.
Gery.J.
1984. The Fishes of Amazonia. In H. Sioli, editor, Monographiae biolo-
gicae, 56: The Amazon, Limnology and Landscape Ecology of a Mighty
River and Its Basin, pages 353-370. Dordrecht: W. Junk Publish-
ers.
Glodek, G.S., and H.J. Carter
1978. A New Helogeneid Catfish from Eastern Ecuador (Pisces, Silur-
iformes, Helogeneidae). Fieldiana: Zoology, 72(6):75-82.
Gosline, W.A.
1945. Catalogo dos Nematognatos de agua-doce da America do Sul e
Central. Boletim do Museu National, Rio dejaniero, Zoologia, 33:1 ?
138.
Greenwood, P.H., D.E. Rosen, S.H. Weitzman, and G.S. Myers
1966. Phyletic Studies of Teleostean Fishes, with a Provisional Classi-
fication of Living Forms. Bulletin of the American Museum of
Natural History, 131 (4):341 -455.
Gunther, A.
1863. On New Species of Fishes from the Essequibo. Annals and Mag-
azine of Natural History, series 12, 3:441-443.
1864. Catalogue of the Fishes in the British Museum. Volume 5, xxii +
455 pages.
Hoedeman, J.J.
1952. Encyclopaedie voor de Aquariumhouder. Amsterdam: De Regen-
boog. [Looseleaf edition.]
1953. Importen . . . voor de lens. Het Aquarium, 23(1):253.
1954. Aquariumvissen-encyclopaedie (Aquariumbibliotheek). 527 pages.
Amsterdam: De Bezige Bij.
1959. Aquariumvissen-encyclopaedie (Biologische BiblioUek). 728 pages.
Amsterdam: De Bezige Bij.
1968. Elseviers Aquariumvissen Encyclopaedie. 186 pages. Amsterdam:
Elsevier.
1974. Naturalist's Guide to Freshwater Aquarium Fish. 1152 pages. New
York: Sterling Publishing Company.
Jordan, D.S.
1923. A Classification of Fishes Including Families and Genera as Far
as Known. Stanford University Publications, University Series, Bio-
logical Sciences, 3(2):i-x + 77-243.
LaMonte, F.
1929. Two New Fishes from Mt. Duida, Venezuela. American Museum
Novitates, 373:1-4.
Lundberg, J.G.
1975. Homologies of the Upper Shoulder Girdle and Temporal Region
Bones in Catfishes (Order Siluriformes) with Comments on the
Skull of the Helogeneidae. Copeia, 1975(l):66-74.
19
20 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
Lundberg.J.N., andJ.N. Baskin
1969. The Caudal Skeleton of the Catfishes, Order Siluriformes. Amer-
ican Museum Novitates, 2398:1-49.
Mago-Leccia, F.
1970. Lista de los peces de Venezuela. 283 pages. Caracas: Ministerio de
Agriculture y Cria.
McAllister, D.E.
1968. Evolution of Branchiostegals and Classification of Teleostome
Fishes. Bulletin of the National Museum of Canada, 221:i-xiv +
239 pages.
Mees, G.F.
1974. The Auchenipteridae and Pimelodidae of Suriname (Pisces, Ne-
matognathi). Zoologische Verhandelingen, 132:1-256.
1983. Naked Catfishes from French Guiana (Pisces, Nematognathi).
Zoologische Mededelingen, 57(5):43-58.
Miranda Ribeiro, A. de
1918. Tres generos e dezesete especies novas de peixes brasilieros.
Revista do Museu Paulista, 10:629-646.
Ortega, H., and R.P. Vari
1986. Annotated Checklist of the Freshwater Fishes of Peru. Smithson-
ian Contributions to Zoology, 437: 25 pages.
Regan, C.T.
1911. The Classification of the Teleostean Fishes of the Order Ostar-
iophysi, 2: Siluroidea. Annals and Magazine of Natural History,
series 8, 8:553-577.
Steindachner, F.
1876. Ichthyologische Beitrage (V), 2: Ueber einige neue Fischarten
insbesondere Characinen und Siluroiden aus dem Amazonen-
strome. Sitzungsberichte der Akademie der Wissenschaften, Wien,
Mathematisch-Naturwissenschaftliche Klasse, 74:49-240.
1915. Beitrage zur Kenntnis der Flussfische Siidamerikas, V. Denk-
schriften der Akademie der Wissenschaften, Wien, Mathematisch-
Naturwissenschaftliche Klasse, 93:15-106.
Steyskal, G.C.
1980. The Grammar of Family-group Names as Exemplified by Those
of Fishes. Proceedings of the Biological Society of Washington,
93(1):168-177.
VanderStigchel.J.W.B.
1947. The South American Nematognathi of the Museums at Leiden
and Amsterdam. Zoologisches Mededeelingen, 27:1-204.
Weitzman, S.H.
1966. Review of South American Characid Fishes of Subtribe Nannos-
tomina. Proceedings of the United States National Museum,
119(3538): 1-56.
Weitzman, S.H., and R.H. Kanazawa
1977. A New Species of Pygmy Characoid Fish from the Rio Negro
and Rio Amazonas, South America (Teleostei: Characidae). Pro-
ceedings of the Biological Society of Washington, 90(1): 149-160.
REQUIREMENTS FOR SMITHSONIAN SERIES PUBLICATION
Manuscripts intended for series publication receive substantive
review (conducted by their originating Smithsonian museums or
offices) and are submitted to the Smithsonian Institution Press
with Form SI-36, which must show the approval of the appropriate
authority designated by the sponsoring organizational unit. Re-
quests for special treatment?use of color, foldouts, case-bound
covers, etc.?require, on the same form, the added approval of
the sponsoring authority.
Review of manuscripts and art by the Press for requirements
of series format and style, completeness and clarity of copy, and
arrangement of all material, as outlined below, will govern, within
the judgment of the Press, acceptance or rejection of manuscripts
and art.
Copy must be prepared on typewriter or word processor,
double-spaced, on one side of standard white bond paper (not
erasable), with 1 VA" margins, submitted as ribbon copy (not
carbon or xerox), in loose sheets (not stapled or bound), and
accompanied by original art. Minimum acceptable length is 30
pages.
Front matter (preceding the text) should include: title page
with only title and author and no other information, abstract page
with author, title, series, etc., following the established format;
table of contents with indents reflecting the hierarchy of heads in
the paper; also, foreword and/or preface, if appropriate.
First page of text should carry the title and author at the top
of the page; second page should have only the author's name
and professional mailing address, to be used as an unnumbered
footnote on the first page of printed text.
Center heads of whatever level should be typed with initial
caps of major words, with extra space above and below the head,
but no other preparation (such as all caps or underline, except for
the underline necessary for generic and specific epithets). Run-in
paragraph heads should use period/dashes or colons as neces-
sary.
Tabulations within text (lists of data, often in parallel columns)
can be typed on the text page where they occur, but they should
not contain rules or numbered table captions.
Formal tables (numbered, with captions, boxheads, stubs,
rules) should be submitted as carefully typed, double-spaced copy
separate from the text; they will be typeset unless otherwise
requested. If camera-copy use is anticipated, do not draw rules
on manuscript copy.
Taxonomic keys in natural history papers should use the
aligned-couplet form for zoology and may use the multi-level
indent form for botany. If cross referencing is required between
key and text, do not include page references within the key, but
number the keyed-out taxa, using the same numbers with their
corresponding heads in the text.
Synonymy in zoology must use the short form (taxon, author,
year: page), with full reference at the end of the paper under
"Literature Cited." For botany, the long form (taxon, author,
abbreviated journal or book title, volume, page, year, with no
reference in "Literature Cited") is optional.
Text-reference system (author, year:page used within the text,
with full citation in "Literature Cited" at the end of the text) must
be used in place of bibliographic footnotes in all Contributions
Series and is strongly recommended in the Studies Series
"(Jones. 1910:122)" or "...Jones (1910:122)." If bibliographic
footnotes are required, use the short form (author, brief title, page)
with the full citation in the bibliography.
Footnotes, when few in number, whether annotative or biblio-
graphic, should be typed on separate sheets and inserted imme-
diately after the text pages on which the references occur. Exten-
sive notes must be gathered together and placed at the end of
the text in a notes section.
Bibliography, depending upon use, is termed "Literature Cited,"
"References," or "Bibliography." Spell out titles of books, articles,
journals, and monographic series. For book and article titles use
sentence-style capitalization according to the rules of the lan-
guage employed (exception: capitalize all major words in English).
For journal and series titles, capitalize the initial word and all
subsequent words except articles, conjunctions, and prepositions.
Transliterate languages that use a non-Roman alphabet according
to the Library of Congress system. Underline (for italics) titles of
journals and series and titles of books that are not part of a series.
Use the parentheses/colon system for volume (number):
pagination: "10(2):5-9." For alignment and arrangement of ele-
ments, follow the format of recent publications in the series for
which the manuscript is intended. Guidelines for preparing bibli-
ography may be secured from Series Section, SI Press.
Legends for illustrations must be submitted at the end of the
manuscript, with as many legends typed, double-spaced, to a
page as convenient.
Illustrations must be submitted as original art (not copies)
accompanying, but separate from, the manuscript. Guidelines for
preparing art may be secured from Series Section, SI Press. All
types of illustrations (photographs, line drawings, maps, etc.) may
be intermixed throughout the printed text. They should be termed
Figures and should be numbered consecutively as they will
appear in the monograph. If several illustrations are treated as
components of a single composite figure, they should be desig-
nated by lowercase italic letters on the illustration; also, in the
legend and in text references the italic letters (underlined in copy)
should be used: "Figure 9b." Illustrations that are intended to
follow the printed text may be termed Plates, and any components
should be similarly lettered and referenced: "Plate 9b." Keys to
any symbols within an illustration should appear on the art rather
than in the legend.
Some points of style: Do not use periods after such abbrevi-
ations as "mm, ft. USNM, NNE." Spell out numbers "one' through
nine" in expository text, but use digits in all other cases if possible.
Use of the metric system of measurement is preferable; where
use of the English system is unavoidable, supply metric equiva-
lents in parentheses. Use the decimal system for precise meas-
urements and relationships, common fractions for approximations.
Use day/month/year sequence for dates: "9 April 1976." For
months in tabular listings or data sections, use three-letter abbre-
viations with no periods: "Jan, Mar, Jun," etc. Omit space between
initials of a personal name: "J.B Jones."
Arrange and paginate sequentially every sheet of manu-
script in the following order: (1) title page. (2) abstract, (3) con-
tents, (4) foreword and/or preface, (5) text, (6) appendixes, (7)
notes section, (8) glossary, (9) bibliography (10) legends, (11)
tables. Index copy may be submitted at page proof stage, but
plans for an index should be indicated when manuscript is sub-
mitted.
i