DE\'ELOPMENT OF DC'vlOXTlA COSTORT;" 351
productjv(' organ~ of reel ,algae. IV. On lJtmumlw <JIn!)ln
CotlOn. Bill!. F(IL Filii. H(lkknld" Uni,?.1 !i:n~-8.
L:me~aki, I. 1967. The ld'dsporophyt,t' of S"rnn/wll 1'"nn;(Illa rt'
Sur. R",,?.?4./Rol. 9: 19-24.
-- 1972. The life hi'lor~' of H)'alrJ.litJluw;a J."af.I!JII".W (Ou?
montiaceae, Rhoelophyta). I Jim. Bol. 47:278-87.
West.], A. 1972. The life hiswrl' of Pf'lmulr,/)'(wr;w/lw Sel.chell
and Gardner. Dr. Phywl. j. 7:299-308.
Wesr? .I. A.. Polanshek, A. R. & Guir\'. M. D. 1977. The life
histor)' in culture of Pdrf/{,I'h, crlll'll/aJ. Agardh (Rhodophyta)
from Ireland. Br. Ph.\'I'O/. .J. 12:4!i-53.
J. Ph)((>l, 20,351-361 (I 984}
Wt'~l. J. A.. Polanshek. A. R. & Sht?.. lin. n. F.. j 978. Field and
culLUre ~LUdit'~ all GigtlrlllWl1gllfdhll (Rhndnphpa). I Plmo{.
14:416-26.
Womersle)', H. B. S. &: Shepley. E. A. 1982. Sourhern Au~traJian
specit'S or HYf!(Igl'l,I.lUm (Oeles;,t'ria('eae, Rhnd"phVla). :\1"/)'.
j. B'I/. 30,321-46.
Zinnva, A. D. 1955. Op),,,'rJ)'III~{jkm,"I,w/r,'ndortl.,I.?j '''''I'nI.Wit tIItJr~j
SSSR, Akad. Nauk SSSR. Mo;,b-:I. pp. 1;7-9.
SEXUAL PROCESSES IN THE LIFE CYCLE OF C;YRODISfUJ,f USCATE.\'['A!
(DINOPHYCEAE): A MORPHOGENETIC OVERVIEWI
D. H'a,YlII) Coals
Chesapeake Bay ltmiwte. Th~' Johm Hnpkill~ l'niversity. Shady Side. Maryland 20764
:~J(J1"Y A. Tvler
College or Marillt' Studje~. tlni\'l'nity of j)(?laware. Lewe~, j)da\\'are 19958
and
Donald i\if. A,I/(lerson
Bi()log~' Deparuut'nT. Woods Hole On"ailO$I"aphIC Inslitution. Wood~ Hole, Massachusetts 02:l-l3
ABSTRACT
Srxual Proft'SSI'S ill Ihl' t~fl' I),rte oj the rIillojlal{l'lIalr
Gyrodinium unralenum Hulburt U't're imll'Jtigaled ill
isola/cd field /JOjJulalirm.l. lUOIpJw!ogirll! and morpho?
/{t'ul'lir asprrt.\ of gail/pIp In?ot!llrtion. IJlnno:ygo{1' jorma?
tion, t'nr)'I{lI/ent. pxc.n/JllI'nI, (j ud planomeiocyfl' dh.'lsiun
an' dr.\rri/Jt'd from oIHf/w/ti(lHS of Iii 'i 1/1( .lIJt'cimn/s. Pro?
largo! sillier impTl'g1J(lf,rd malrria! and .~rmmil1g rlrrlron
micro!ico!JI' IJre})(/ rations. TlU! .~f.'l:U(l! cyrtf' Wfl.\ in/tialn! b."
gamde pJrmaliOll u'hifh im'oh'I'd hm (/,ll'xlIal dir'Bions rJr
tlrl' 7'f'gf'lativf' organism. Calnl'tl's wpr(' flllt)' difjrl'l'ntialn!
jollou'iug the S/'umd dii'isi,m ami imml'diflfr(\' m!Hlb!1' of
forming pairs. Eilht'T iSt/gamoll., or aniwgamou.,' pain
were JOT/lI/'(1 Ii)' Ihe mid-tlrn/rat union o/wnnl'le.l. Comfit's
im'(J riably joined wilh flagf'llar bO,H'.1 in do.\/' jux/al}!)"i ?
lioll. Com/dell' fusion OIK(wU'If'~ reqllirl'll fa. I h. im'oh'ed
plas/1/ogamJ follo'wed b)' karyIJgnm,\' {{nd resulted ill (I
quadriflagrtloled plnuozygotl'. Pia nozJgol/' I f'lll)'slfd ill
24-48 h /0 yil'ld (J h)'1moz.ygolr ml}(1b{e oj 01 'rr..I'inIf'ring
ill ntutl rine s"dimt'lils. H.."pnoz)'WJ/rJ rollull?d /J'om SNJi?
rtlrnt in la/r winln /"tladil)' e.'l:(~"!ill'd UPOIl I'xpusure 10 It'm?
/)1' ra lures abot't' JJO C. A sing'l' qUti rl riflagl'ltalert pia11?
omeilJ(J'lI' emerged from (h(' 1)'.11 Gnd limit'/' rul/ure
conditions dh,jr/nl one to l;tIo days lain. Thrfour{fagrlJa
iNre not t'l't'rI(1' liisiribult'd at t.llI' fint di7?i.\/on ami both
bi- and /I'i-{fagfllatNI daughli'" crt(, U'l!reformnl.
I Arrrplnl: J5 Frl>nwr.~ /984.
Key illdf'x u'/mh' f1l()'.1/1rI1'1l/; rxcy~tml'Ht; j;(l/TII'/e: Gr?
rodinium uncatenum; h.'fpno~yglJll': IJlano/flf'iof'yI/':
I)/a noz)'gfJ if'
The existence of <i sexual phase in the life cycle
of dinoAagel1:ues, while a source of conrroversy for
some time, has in the past twO decades been well
documented in numerous species. Much of this ef?
fort has focused on identifying various develop?
mental stages and characterizing the sexual cyc1~'
(von Stosch 1965, 1973, Cao Vien 1967. 1968. Zing?
mark 1970, Pfiester 1975. 1976, 1977, Turpin el
a!. 1978, Walker and Steidinger 1979). However,
several investigations have employed cytological and
uItrast.ruclural techniques to examine specific as?
pects of the sexual process in greater detail (Sko?
czylas 1958. von Stosch 1964, 1972, Spector et al.
1981, Chapman ef al. 1981, 1982). \Nith rare ex?
ception (Bibby and Dodge 1972, Chapman et al.
1982), knowledge ofdinoflagellate sexualil), has been
derived from observations of c:ultured organisms.
The lack of comparable obs(~rv,,-tiom for fi'e1d pop?
ulations may, as sUJl,:gested by Chapman fOt a1. (1982),
result from the sexual process being a short lived
phenomenon or occurring in only a few cells at any
given time.
The recognition of a resting stal{e (hypnozygote)
352 D. WAYNE COATS ET AL.
as pan of the sexual cycle stimulated additional in?
terest in dinoflagellate sexuality. The significance of
nypn07.ygotes as seed populatiom for establishing
dinoflagellate red tide blooms is recognized (An?
derson and Wall 1978, Anderson and Morel 1979),
and attempts are being made to identify environ?
mental factors which stimulate development of var?
ious sexual stages (Anderson 1980. Watanabe et al.
]982, Pfiester and Anderson 1984).
Recently, we reported the effect of hydrography
upon the deposition of GJl"odinium !Wea/fllUm cysts
in estuarine sediments (Tyler et al. 1982) and have
examined factors effecting encystment in culture
(Anderson, unpublished observat ions) and germi?
nation of seed bed populations (Tyler, unpublished
observations). Here we repon on morphological and
morphogenetic aspects of sexuality in isolated field
populations of G. Ullwimum.
~ATERIALS AND METHODS
To examine eveJlt~ It''ading io encysr.ment. a 57 L Nalgene
cylindrical tank was filled with water taken by bucker from a
~urface G),rotlilllulfl lwcalmllrll bloDm IOGlled in Baltimore Har?
bar, Maryland (39?1 r,' N; 76?34' W). The population was isolatl"d
al 09:30 h August 18,1980 and held on deck where it was exposed
tel the natural Iigh. regime and maintainf"d al ambient temper?
:iture (ca. 259 C) by continuously bathing I.h?" outside of the wok
with baywaler. Tht:' isolated population was thorrlup;hly mixed
immediately prior to sampling by repeatedly thruslinp; the broad
end of a 2 L graduated cylinder IOward lh(" b.mom of the lank.
This method of agitation simulated shaking. avoided the pro?
ductinn nf a large vortex as in slirring and resulted in an even
dispersal of organisms. Samples wcre arbirr-arily drawn from the
upper half of t.he tank at 30-60 min intervals fm 48 hand th ...n
less regularl)' for an additional 52 h. At each ~mp1ing interval,
20 m L aliquots were preserved in a modifi('d Bouin's fixative
(Coats and Heinbokel 1982) and refUrned to .he laboratory for
subsequent staining by either the Bodian protargoI silverlech?
nique (Tu/frau 1967) or a regrt':\~ive alum hematoxylin procedure
(Galigher and Kozloff 1971), F.,tirnates of cell concemrations were
obtained by counting the indi\'iduals presem in single l-mL ali?
quots of presened samples. PeTTentages of di,'iwng cells and
fusing gametes were determin..d from hematoxylin stained ma?
t('rial. The firs! 500 individuals encountered in each sample were
tallied as nondi\'iding cells. dividing cells or fusing gametes. Early
and latt' developmental stages wen'" given ...qual weight and thus
even "figure-S" slages. whelher dhidillR L'ells or fusing gamet("s,
were counted as single indh?iduals. The JWTt'eIHage of cells as
pl;lJloz~'gotes was similarly deri\'ed from .Protargol preparations
with 100 individuals being enumerated lor each sample. Stained
specimells were examinf"d and photographed 011 a Zeiss micro?
scope equipped ",-jlh phase contrast opl.ics and an Olympu~ OM?
2N camera. Cell measurements ""ere made of ProtargoI stained
specimens using a calibrated ocular micrometer.
Excystment ill G)'rtldinilll1l IwminWIfI was invcstig-.tted \,Ising
hypllOl.ygotes isolated from sediment OIl (:a. 4? C during Fe-hrua!)'
1982. Sediment from Parish Creek (38?50'44" N; 76?30'31" W)
was collected using a Petersen dredgC" and c!t:'alled by Ihe method
of Wall and Dal.. {l90S}. Sedimellt was disaggrcg-.lled bv pulse
sonicar.ioll for 1 min using a Branson Snnifier Cell Disrupt..r 200
that delivered 30 W at 0.5-s inl.ervals. Hypnozygn[("s were cul?
h.-ctecl by sie\'ing the resulting slurry through 64-20 IJm Nite"
nyloll screens. Cleaned hypn07YRott?s were Iransferree! to In'h
"'1/2" phytoplankton growth medium (Guilla rd and R}'lhf'r 1962)
producing a 2 L "culture" of ca. 100 G. 100miOlutli I?YSr.S mL ".
The "culture" was incubated at 20? C on a 12: 12 h light-dark
cycle usinll General Electric Cool-White fluorescent bulbs with
lig-ht intensity of IOOIlE?m"?s?'. Twemy-milliliter aliLJuots were
Laken al varying iuten'al:; and processed ;IS desnibed above.
ObservaTions of ('ultured G"'rodmmlll t"'mlrltlllll ",ereura strain
isolated from the Potomac Rh'er in the summer of 1979and main?
lained at room temperature (20-239 C) on 15 and 30~ "1/2"
phylOplankton growrh media. The isolaH' was unialgal but not
axenic or donal.
For scanning electron microscopy. oTj~anisms were prt"sened
in a variel.y of solutions withnsmium tetroxide-aqueous mercuric
chloride fixative (Parducz 1967) producing the bl'S! l'esuhs. Pre?
served specimens were transferred through multiple distilled water
washel', freeze dried using a P('arse-Edwards tissu(' c1rye'T, coated
with a gold?palladium allo), and examined on an A:\1R IOOOA
scanning electron microscope.
RESL:LTS AND D1SCL'SSION
Sf'.'>;lUdif)' and I'1H'i'Jtmeni. To determinE' the de\'e1?
opmcntat" events associated with encystment. GJm?
dinium u-ncaimUJn from a bloom was transferred [0
a large container and routinely monitored for sev?
eral days. Subsequent to tapture, a large proportion
of the G. unrtltf'llran cells began the sexual life cycle
phase, thus permitting close examination of mor?
phological and morphogenetic aspens of sexuality.
At the time of isolation (To), G. unratPl1um numbered
ca. 750- mL -I and resembled the species description
of Hulburt (1957). Protargol stained specimens av?
eraged 33 x 29 ~m with individuals ranKing through
a two-fold difference in size (see Table 1). Trophic
organisms possessed a spherical to slightly ovoid nu?
deus with condensed chromosomes and generally
two (range 1-5) nucleoli (Fig. 1). Cells had the typ?
ical dinoflagellate complement of two flagella with
the striated strand and flagellar bases (= basal body)
also staining deeply (Figs. 1. 2, 8, 9).
Early in the experiment, G. uncutenum increased
significantly in size and had more than doubled in
volume by T Ir, (see Table I). Other than their larger
size, T lr, cells were indistinguishable from those of
Til' During this period, G. ullwlnwm reproduced
asexually and numbered ca. 930'mL -I at TJ~' Di?
viding cells were infrequently encountered bet'ween
Til and T 15 and never comprised more than 37f of
an~' sample. In the following ten hours (T,>-T2~)'
the abundance of dividing c.'ells was considerably
higher and Protargol staining revealed the division
sequence summarized in Figure 12. The first indi?
cadon of division was the replication of Aagdlar
bases resulting in four basal bodies arranged in two
pairs (Fig. 12b). Elaboration of new flagella ensued
immediately after basal body replicat ion and was
completed by mid-division. As cytokinesis pro-?
ceeded, flagellar hases moved apart and each daugh.
ter cell received one old and one new basal bod ....?
flagellum complex (Figs. 3, 4, 12c-e). Nuclear and
nucleolar elongation accompanied flagellar separa?
lion, and mitosis occurred as described in other free?
living dinoflagellates (Dodge 1963). By late division,
cells were loosely auached al the epicone and f1a?
gellar bases of the two daughter c.ells were widely
spaced (Figs. 5, 12f). .
353
T~~l\LF I. C~/f m.l' mu/ ,ltu/"Ilr ch<1r11(/~ri.,llnuf d,w/"lmIFlllnl,ta/{t" luwrillird with "Ilf)?.<lmnll ItI Ih~ I.",hrlfrl Gyrndinium UI1Gl!l'nUm b/"'l/IJ
p"/lIIlati/JII.?
~~lomalil ~1.utt".1t '\itltL'"11Ii c~11
"'~Ilum.?'"r.
I. W
"
W 11 ......
"
~ I( 10' f;ifU")
TTI:lphic <:dl~ (To) X 33.3 28.6 ~\() 13.1 10.5 30 2.1 30 1.4
Range 24.7-40.2 21.6-:~6.1 9.3-15.4 7.2-15.4. 1-3
S 3.67 !I.6R [,fl6 2.08 0.[,:1
Sf 0.67 0.67 0.28 0.38 0.10
Pre-division !!"Ophir: X 49.2 42.0 30 14.2 15.3 30 2.2 30 4.:'
cells (T,,) RanKe 36.0-64.9 31.9-56.6 11.3~18.5 11.:~-18.!i 1-3
S 7.01 6.02 1.48 1.81 0.55
Sf 1.28 1.10 0.27 0.33 0.10
Gamete~ (Td X 31.2 21.4 60 12.4 9.8 60 2.1 35 1.0
RanKe 21.6-41.2 13.4-28.8 8.2-20.6 7.2-11.3 1-4
S 4.34 3.29 1.78 0.93 0.47
Sf 0.56 0043 0.23 0.12 0.08
Planor,gores ("r~~) X 43,4 38.7 30 15.1 13.9 30 4.2 24 3.4
Range 33.0-50.5 27.8-45.3 13.4-17.5 11.3-17.5 3-6
S 4.71 4,49 1.10 1.75 0.83
SE 0.86 0.82 0.20 0.32 0.17
f'lan()1.rg{)!e~(T.,;) X 44.6 37.0 30 14.7 13.3 30 4.8 30 3 'l.~
Range 38.1-50.S 28.8-46.4 12.4-16.5 11.~-15.4 3-7
S 3.67 4.:-13 0.93 0.93 0.99
SE 0.67 0.79 0,17 0.17 0.18
Newly rormcd cy~l;~ X 48.2 38.8 30 9.3' 30 4.1 30
(T t?? l) Ran~(" 41.2-54.6 33.0~H.3 8.2-11.3 3-0
S 3.94 3.07 0.80 0.71
SF. 0,72 0.56 0.15 0.13
? All observations are of PrOtilrgo! ,i1vt'r slalnt'd specimens,
" Cell volume~ were approximated llsinl\ the hlrmula for a prulate ~pheroid and m("an length?widlh mea~t1remenls.
, Measuremt"nLS rf'pn'sem the diameter of the spherical cpt nudeu?.
The elevated period of divisioll between T I~. and
T2~ displayed two distinct pubes with each spanning
4-5 h and peaking with 15-20% of the population
as dividing cells (Fig. 13). Cell density increased rap?
idly during this time and had almost doubled by the
end of the first division pulse (1'21)' Apparently most
individuals had completed one fission prior to the
second diVision pulse. Cell counts continued to in?
crease during the second pulse and reached ca. 2100?
mL -1 at T2~' That Gwodilli!un numbers more than
doubled from T I~ to -1'2. suggests that at least some
(:e1ls had divided twice. Following the sewnd divi?
sion peak, the number of CymdinillJn dropped to ca.
1800'mL- l thus showing a net two-fold increase over
1'1" cell density.
Near the end of the first division pulse, several
pairs of G. UI1ClllnllWI were observed loosely joined
equawrially rather thar"J apkally as in late cell divi?
sion, Cytological staining revealed such pairs as rep?
resenting the earliest stage of gamett' fusion. Ga?
metes were smaller (ca. 0.25 of the cell volume of
T.>, cells) and rather variable in size but otherwise
indistinguishable from pre-division trophic individ?
uals (see Table 1). Since vegetative organisms and
gametes had very similar morphologies, nnly those
cells which had begun fusion could be unt~quivocally
identified as gametes. Therefore, meaSLlTemelll.s for
gametes presented in Table 1 were taken from cells
in very early stages of fusion, Most coupled gametes
were of relatively equal size (Fig. 6), but a few were
anisogamous. Anisogamous pairs were particularly
abundant in old laboratory cultures and occasionally
observed in field samples (Fig. 7). Paired gametes
were typicaIly oriented as mirror images, but their
longitudinal axes were occasionally skewed to per?
pendicular as reported for Ptychorlisrul br!'1.'is (Walker
1982). Asymmetric confiRurations were common in
cultures, and gamete pairs were observed where the
epicone of one cell was acUacent to the partner's
hypocone. Misaligned gametes of Wolos:.)'lukia a/li?
eulata are reported to become reorientt,d prior to
fusion (von Stosch 1973). The same appears true fOT
G. unca/nlum since gametes of later fusion stages
were always aligned as mirror images,
Following the first division pulse, fusing gametes
became progressively more numerous and peaked
at ca. 22/k of total motile cells mid.way through the
second division pulse (Fig. 13). The nearly simul?
taneous rise in second division cells and coupled
gametes suggests that gametes are fully differen?
tiated and capable of fusing immediatel~' after the
second of two sequential divisions. Fusing g'J.ffietes
were abundant for ca. 7 h (1'22-T29) but persisted in
verr low numbers until T~lj' Cytological staining per?
mitted close examination of gamete fusion. and the
morphological events leading to planozygote for?
mation are illustrated in Figure 14. The inilial union
of p;ametes occurred midvemrally at the location of
354
------
5
D. WAYNE COATS ET AL.
Non-: scales - 10 ~m [or figures and:' JJm for figure insels.
FI(,'o. 1-7. CJrot/lllllltfl l//lra/PIlIIIn_ FIG, I. Four l'romrgol :o.,ilvrr stained \ eg~lali\'(' t.elhl. Each orgalll1<.m has a :tingle Ir3n.s\Crse Aagdlum
(tf) ""uh stri:ued sirand (arm\\s) and a decpl) slaining nucleus (n). IIl~t: Protargol statnt."d trophic nucleussho\\ ing the I) picaIcomplement
of two nucleoli. FI(.. 2. Ilrolargol stained trophic cell shoh'ing the single poslcnor ftagellum (pi) alld the two f1ag'ellar base:> (arrows).
FIl?. 3, An earl)' stage in asexual di\?jsion \'Iith oolh scu of paired bas-'ll bodies (bb) in focu'!. Also e\-idem IS the paremal poslerior
flagellum (pi) and a nascent lr.U1s\'er!te Aagel1um (arrow): Protargo\ stain, Fu;. 4. A mid-asexual dl\isioll slaKc sno\\'lng an increased
separalion bc:lwccn the lWO sets of bJ.531 bOOies (arro\\'s): Prolargul qain. fiG. 5. Kanokinc'il.'i is nearl)' l"ompleted in lhill late division
specimen and the basal bodies (arrows) of the IWO daughter cells arc \\'idel) spaced. FIC:,. 6, A n'ry e:lrly stage ur Hamclc ru!>ion. Gametes
are or equal size and aU<r.ched J1lld?v~tralh' al the !oc,Jtioll or the basdl bodies (bb). The tran!>\'crse flaRdlum (If) and pmll'rior 1t:lgdtllm
(pf) or t:ach t.ell'lre also discernible: Prot:trgo] Slain. FIG, i. t\ pilir of anisoKamous G. 'I1Im/"III11I/ gametes isolalcd from Parish Creek.
Phase contn'ISl of li\?jng malt?rial.
SEXUAL l'ROCESSES LN CrnODIXIL'.\f 355
FIG'?. 8-11. G)rodHUUHI mlwtt'num. fit... Scanning electron micrograph of a trophic cell showing the lvpica! bod.. )hape and the
lrans\'erse A3~ellum (If) displaced frum the girdle (g) during fixation. fIG. 9. PU~lerior vie.... or 3: \t"geI311\t:' cell ",ith the posterior
Itagellum (pI) emerging from decp in the ..ulcus; trans\crse flagellum (I I). fiG. 10. A recentl~? excyslcd IllanomelOC) It' "uh fWO posterior
flagl"lla. The tWO trans\er~ flagella were losl durinR s~imen prepar.lli(m. FIt.>. II. High magnific..nion of the t"O tr.mSH'NC flagella
(arro.... .) ofa planomcioqlr.
Lhe Aagellar bases (Figs. 6 and 1?la). From the onseL,
basal bodie of fusing gameLes were in close prox?
imiL " in comra Lto lhe "figure-S" sLage 0 cell di?
vision (Fig. 12f). The nuclei of early rusers were
elongaLed to"'ard and linked to the basal bodies by
an argemophyllic maLrix, At lhis sLage, the connec?
tion between the twO gamete was similar to the
fertilization tube of Pl'ridin;um tillclulIl f. OVop/llllum
(SpecLor eL aI. 19SI); however, ka ryog-d my occu rred
much later as reported for several other dinofla?
gellaLe species (von SLosch 1973, Pl'eisler 1976, 1977,
Walker and Steidinger 1979). As plasmogam)' pro?
ceeded.lhe (wo longitudinal flagella became aligned
and in living ?pecimens were seen to function in
unison. SimuILaneousl)', the tranwerse Aagellum of
one gamete migrated OUL 01' the girdle and eV'en?
tually lay adjaCenllO the (r3llSVerse fiagellum orthe
oLher gameLe (Figs, 14 b-d and 15-17). pon com?
pletion of c),toplasmic fusion, rorming L)'goLes pos?
sessed twO trailing flagella, twO transverse Aagdla
beating together within the single girdle and two
nuclei (Figs. 14d and IS). PlanOZ)gOle rormation was
finalized by the I'll ion 01' the Iwo nuclei 10 produce
a nucleus usuall), containing 4 or 5 (range 3-7) nu?
cleoli (Figs. l4e-f, IS inseL. 19 and 20).
PlanozygOle occurrence lagged behind and c1osel)'
356 D. WAYNF. COATS ET AL.
~':!J .. ~.': . b
~'($.; .:;C,'ii' \-..! .: r
ft(;. 12a-f. Semi-diagramm'llit: camera lucida drawingsuf
asexual division in Gyrodiuillm ,nwI/mum as revl'alecl by Prnt<trfi(0J
silver S1aining.
fig. 14a-f. Semi.diagrammatic camera lucid.. illustrations of
gamt'tt." fusion in Protargol Maineci Gymdi1ri'llm .mea/mum.
FIG. 13. The events associated with pl<tnozygote fGnnation in
the isolated G}rodi,,,ulI/ Ullwlmurn population are graphically de?
picted. Abundances of major devdopmcmal ,rage. an' expressed
as percentages of tne population (left vertical axis). Percents 01
dividing cells and fusing gormetes were derivl?d from alum he?
matoxylin prf'paraliom with n ~ 500. The frt'quency nf plano?
zygotes was obtained after Prolargol stail1inll witn n = J00. Pop?
ulation densities. shown on the right \'ertital <lxis, represent sinKlc
counts of I-mt volumes. NumbeFS of genornes. comput('d as
explained in the texl.are shown in pal"entheses next 10 ce!l counts.
Black areas indicate the inwnal betwf-en suns{'1 ami sunrist'.
paral1eled the increasing abundance of fusing ga?
mete pairs (Fig. 13). Between T2:~ and TIro the per?
centage of cells as planmygotges increased rapidly
before leveling out to 80-85~ of the population.
The narrow gap between increasing percentages of
pairt'd gametes and planozygotes indicates that plas?
mogamy occurred quickly and required ca. I h for
completion. Furthermore. the l'ailure of total cell
numbers to increase dramatically during the second
division pulse is explained by the swift coupling and
transformation of gametes into planozygotes. Since
fusing gametes and planozygotes represem devel?
opmental stages endowed with two nuclear comple?
ments, the number of genomes present in samples
can be obtained by appropriately adjusting total cell
count; i.e. no. ofgenomes = no. ofcells'mL-1 + (no.
ofcells' mL-1).(9( fusing gametes + '1c planozygotes).
Manipulating the data accordingly produces the val?
ues shown in parentheses on Figure 13. Thus, be?
tween Tit, and T!O. the total number of genomes
showed a 3.6-fold increase from 930 to 3300?mV 1 ?
This nearly four-fold increase in genomes supports
the concept that gamete differentiation requires two
successive divisions. While other explanations are
possible (viz. some cells dividing once with others
dividing 2. 3, or mOTe times), the former is consistent
wilh the double peak in division frequency and with
gametes having about one-fourth the cdl volume of
pre-division (T,~) cells.
Planozygotes averaged 43 x 38 ~m shortly after
fonnat.ion (T~~), persisted without significant growth
for several days and then encysted. Cysts were first
evident at T~I' but accumulated slowly at first and
only comprised ca. J7f of the population at T~I)'
Encystment proceeded more rapidly thereafter, with
the population consisting almost entirely of hyp?
nozygotes at 1'100' Planozygote maturation prior to
encystment required 60-80 h. However. the timing
of this period is rather variable and dependent upon
environmental conditions (Anderson, unpublished
observations). The anual encystment process ap?
pears more conservative and, once initiated. re?
quired slightly under 24 h for completion.
As discussed in Tyler et a!. (1982), encysting plan?
ozygotes become less motile, lose much of their pig?
mentation. and round up. Eventually, the flagella
are lost. clear storage granules form, and red pig?
ment granules develop. Newly formed cysts from
the isolated bloom population averaged 48 x 39 j..lm,
possessed a spherical nucleus with four (range 3-6)
nucleoli and three cYSl walls Crable 1, Figs. 21, 22).
The outer wall was looselv attached to the cyst and
often removed by proced~res lIsed in c1eani;lg and
collecting cysts from sediments. By comparison. the
middle wall was durable and rather rigid. The inner
aoo
'800
1001)
~ooo
'.200
~
1400 ~
~
&
1200 -J:
..
[HDII
.---. "'lJmb.r ~ ml+l
PIIJc....d ~ -UM:IUftllII!I 0.'
+-+ D(i;"~dltt1;l ~.lIrr
a-a flol'~I'IQ plI'unrr pOi",".
.. - .. P~~"''\I~ff.
..
(11M)'
,.i
',1101.
'0 ~ ZO ~ ~ " 40 ~! ~
E.lnp!l't!!lj T,me iHI~~
",,1
I
i1.
rD?
Q ~OJij;!!
u
~
'?1""~
u
U
c% ~o?
~
0;
OJ
'I JO
15
EXUAL PROCESSf:S IN GY//OD1.v1L'.1I
16
357
17
18
19 20
FICs. 15-20. Crroc/wuon U."rotnlllln Flc.... 15-17. This through.fucoIl ~rie:,> of a mid-:Ol=tge In g:.amt'u? fu!Oiun ..ho", Iht" proximil) of
the ' ....'0 rosal bod~ pairs (" hitc arrov.s) and the lack. of a connection between the (..,'O nuclei. The posterior flagella (pI) are ~n in dose
associallon. The Iran..-.. crS{' flagellum ofone cell (arro"') j!j displac-ed lrom i,<; girdle .....hHe Iht" other remain" firmh positioned: Protargol
$Iain. Flc. 18. In this ad\'anccd stage of plasmogamy the twO gametic nuclei Temalll disunct and app<tTcntl)' ulljoinl'd. (mel: A (aler
slage in ru~ion "here k:lr)og-dmy has bt:gun. ~olice the presen e of four nucleQli: PrOiargol Slain. Fit,. 19, The- I\\'U lr:uling fbKella 3rt.'
evidem in lh,<; plano7ygOlt: 'whose nucleus (inset) ha .. almo~t complC'tcd ru:-ion: Prot.argol "lain. FlC~. 20. A group oj p1:1Il0/H{OICS ""hne
each cdl bt';.trs IWO Iram\'('rse flagella (arrow.!I). The Slri'llcd 5lr.llld often Sl311lS lightly and IS not \l~ihle il1l1l{:~e spe(lInem: Prmargol
11l3in.
358 D.II"AYNECOATS ETAL.
FIC~. 21-27. C... ,odnllum Imratt'num. FI{;. 21. H"pnU/\golelt with dear storage granule~ !iurrounding the dark or,lOge-red pigment
globulo (pg). The thr~ la\'ered nature of the CYSl ""'all IS apparelll at the whitt' arrows: bright field, li\ e specimt?ns. Fl(,. 22. PrOiargol
:.tained qSl5 sho","?jng the densely stained nucleus (Il) and three cY~1 wall~ (arrow~). fuscl: A CYSt nucleus containmg four nucleoli. FIG.
23. A cell nearing t'xq''ilmelll. Formation of the sulcu'l and the girdle are well advanced. red pigment globuleli 3fC' pr~", posteriorh'
and numerous large clear grdnules afe dlsper\ed in rht- c)lOplasm: brighl field. live specimen. FIG. 24. Phast' COntrolSl of a lIewl) exC)'sled
planomejoc)'u~ wilh red pigmelll Klobult-s Stilt prcM:"n1 subequ;ltoriall): li\'c specimen. Fit?. 25. PrOlargol i<oUlill of a recL"llll) cxc\sled
planomeioc)"lC:' !>ho'A'ing four nucleoli IOC:lled pe:ripheralh "ilhllllhe l1uclcu~. Fit .. 26. A planomcioc)'lf' nearrng the firsl meiolic di,"ision.
Tht> enlarged nucleus conlaim a single nucleolus and large' cil:.tint:t chromo:.omo: I)rolargol ~L:.Iin. fl(;. 2i. Lale in the firs! meiUlu.'
division. alice the 1\0,'0 posterior nagclla of Ihe lo\\er daughler cell and the elongalcd chloroplasts (arro....'!o): pha.se COll1ra"L Ii\(.
!lpecimen.
SEXUAL PROCESSES.l~GrROfJI.V[(';\J 359
Surrl~jll\
I. w
"
L \"
9.!i'?
8.2-11.:\
0.88
0.16
Cyst~ approaching
excvstmem cr??)
ReH'11 tl \. ex t:\'sled
mt"ioc'yle ('1"-0)
PrI'.Qj \'isi un
meicX'yle (Tsu)
X
RanK"
S
Sf:
X
RanK('
S
SF.
X
Range
S
SF.
46,7
38.1-59.7
4.66
0.85
35.0
29.9-42.2
:1.31
0.60
34.6
30.9-40.2
2.44
0.45
38.2
29.9-:10.5
4.55
0.83
28.2
24.7-35.0
2.60
0.47
:H.O
23.7-36.0
2,98
0.54
30
30 IVl
10.;1-17.5
1.46
0.27
17.0
13.4-20.6
2.16
0.39
11.4
~1.3-14.2
1,09
0.20
14.5
12.4-17,5
1.24
0.23
30
30
3.B
3-6
o,n
0.14
:~.Il
2-6
0.9:.
0.17
1.4
I-:i
0.70
0.13
30
30
? All obsen-alions arc of Jl.mlilrgol silver slaillt~d spetimt'ns.
" Measuremems represent The diamett'r of tht' spht'rical cyst nucleus.
F!(;. 28. Abundanct' of" major dewlopnwmal ~talol('s an:um?
panying excysUnenl in G."r~di1mHllll>lmlpntl/li. PlanomeieX'ytes with
"Knaud"-stage nuclei (o) weredetcrmiTlt'd from prulargol ~lained
samples (n = ~O). The percentages of G,v'odinil<;n a~ hypnD~rgnle~
(e), dividing cetl~ (a) and IOtal plallomt"iuc~?t('s Wt."re de[el'mined
from tixed unstained samples (n = 100). Planomeioq'tes withuul
'"Knauel"-stag'-' Ilu(:lei (X) wen' ('(,mpult'd by sublraninn.
~;:~--'.')~-' d
~".~t::'.~" '.~',' "~i :. 11~-;~._-~.~.""I\.:?~~_'~~, J.: :~ r
~,~,':'-7.~';.1<'.: Ij b
~:~~.-, ?
to?',. .J".... ?
cystmem progressed and flagella wert" elaborated.
Just prior to excystment, germinating cells still con?
tained red pigment globules and numerous Clear
storage granules (Fig. 23). With development of fla?
ge lla , zygotes became active within the cyst and
eventually exited through ruptures in the middle
and. when present. outer cyst walk
Excystmelll began at ca. T."" where Til = time of
transfer to 20? C, and proceeded steadily until ea.
957r. of the cells Wf'I'e free swimming at T,(I' After
excysting, G. lfllCllil'1lU11J had fc?w storage granules
and little cytoplasmic coloration. but red pihrment
globules generally persisted il1 a subequatorial po?
sition (Fig. 24). The nuclei of these organisms were
spherical to ovoid, slightly larger than those of cysts
andusually contained four (range 2-6) nucleoli (Ta?
ble 2, Fig. 25). Recently excysled G, lIl1m/fllum are
presumably meiocytes, since planozygotes did not
divide prior to encystment and only one cell emerged
from the cysr. [n addition, the persistence of four
nucleoli from planozygote formation through cyst
germination argues against the existt'Ilce of nudear
reorganil..ation during encystment. Like planozy?
goLes, the meiocytes of G, IIllfalnlllm had two pos?
terior and two lransvnse flagella (Figs. 10, II). and
FIG. 29a-g, Semi-diagrammatic ('amera lucid;i iIIuslrations of
[he sequenti<ll stage~ in planumeio(:yte dt,w!opmenl. from eJ<:?
cplmentthrough the first cell division: (a) recenth exc>'~led plal1?
omeiocyle: (b) "Knauet"?stage: (c-g) fir~t meiotic division.
/\
~
.,
.(
~ \ ~.,
"~,
10
u '0
.0::
"
"0
..
0. 30
'"~ lo
? 10
U
~
wall, which may represent the cell membrane(s), was
flexible and often crenulated after staining and de?
hvdration.
,Exc:,:simrnl awl plmw1fl/>iol}'fi' dil'i,ion. Cysts collect?
ed from sediment in late wimer readily excysted
upon exposure to temperaLUres above 15" C. Aspects
of cySt and meiocyte development were examined
by stimulating freshly collected cysts to germinate,
These cysts were morphologically consistem with
those formed in the isulated bloom population. Pig?
ment accumulations, storage granules, nucleoli
number. and nuclear and somatic size were com?
parable for the two cyst populations (compare Ta?
bles 1 and 2). Many of the overwintered cysts lacked
an outer wall which was presumably lost during sam?
ple preparation.
The earliest indication of excystment was visible
30-35 h after cysts were transferred to 20" C. Mor?
phological changes included a widening of the gap
between the middle and inner cyst walls and slight
indentations at the developing sulcus and girdle.
These features became more pronounc('d as ex-
360 D. WAYNE COATS ET AL.
following the recommendation of von SlOsch (1973)
would be appropriately termed planom(?iocyr.es. ]n
the 24-48 h following excystmem. planomeiocytes
lost their red pigment globules, developed lal'ge
chloroplasts characteristic of G. 1I11((/lrIW/II, and took
on an even reddish-brown coloration. During this
time, the nucleus dramaticallv increased in silt' and
eventually occupied much ot the anterior ponion
of the cell (Fig. 26, Table 2). Enlarged nuclei pos?
sessed only OIle nucleolus and large. wt'll defined
chromosornf's which wert.' often paired. This con?
dition represents the "Kn<luelstadium" described by
Borgert (] 9] 0) and later associated with nuclear cy?
closis and postzygotene phase of meiosis (Skoczylas
1958, von Stosch 1964, 1972). G)'l'odinit//11 with
"Knauel"-stage nuclei appeared about 24 h after th('
start of excystment (Fig. 28). Cells whose nuclei con?
tained a single nucleolu~ soon comprised ca. 65';k of
the population and thell decreased in abundance
with the onset ofmeiosis. Dividing cells were present
in low numbers ca. 15h after the development of
"KllalJeI"-stage nudel and reached a peak frequency
of II o/c at T 91 : thereafter, dividing organisms re?
mained in low numbers.
The first and second meiotic divisions in G. 101?
rafl'111WI were not closely associated in time. and only
cells in first division stages were enc()untered in
stained preparations. Figurt' 29 illustrat(~s the de?
velopment of the planomeiocyte through the first
meiotic division, as revealed by Prolargol silver
staining. Following nuclear reorganization, cell di?
vision began with one of [he transverse flagella sep?
arating from the remaining three fl,agt'llar bases (Fig.
29c). Two new argentophyllic granules then formed
in association with Lht' isolated flagellar base, which
resulted in a tmal of six granules arranged in two
sets of three (Fig. 29d). The set of three "parental"
flagella and basal bodies are destined for one daugh?
ter ct,'II, while the other receives one "parental"
transverse flagellum and differentiates a new pas?
[{'rior flagellum (Figs. 27. 2ge-g). In late division
stages, the cell with t .....o flagella contained variably
two or three argemophyllic granules, but ouly two
bases appeared to persist after cytokinesis. Whether
the niflagellated daughter resorbs one of its pos?
terior flagella or returns to the vegetative nmfigu?
ration at the second division is unknown. As flagella
were being redistributed. the already enlarged nu?
cleus elongated and the single Ilucleolus usually di?
vided twice, thus furnishing each daughter cell with
the normal complemenr of two nucleoli.
The Protargol silver staining: technique is rou?
tinely used in the study of ciJiated protozoa. but is
infrequently applied 10 flagellates. The procedure
is somewhat tedious but simultaneouslv revt'als nu?
clear and cortical structures. In the p~esem study,
Protargol staining proved useful in elucidating cy?
tological aspects of sexualit}, in G. IlI/('a/f'llUm and
provided valuable markers for the identifi':ation and
enumeration qf sexual stages in experimelHal and
field populations.
Research was supported by National Scient'e Foundation Gram
OCE-80111139. Contribution no. 281 ur the Ches;lpeake Bav In?
stitute, The Johns Hopkins t.:niversity. no, 176 01 the l'ni\'ersitr
of Delawan' and no. 5474 of I.he WliOds Hole OCt',lIlogniphic
Institution. We thank Dr. E. M. Hulbu.rt for spe('il:'S identificatinn:
Mr. T. K. Maugd and th.. Laboratory for liltrastmctural Re?
sean:h, Depanmem of Zoolog}" Lini\'l:'rsit> of Maq?land, College
Park for lISt~ of thdr fadlity: Mrs. C. Q. Eisner f(lr re.:hnka[ help:
Ms. L. A. Reid fot graphic ill ustrariOll5: and tht' Caplain and ('re\\'
of the R/V Warfield for ship operations and on?dcrk assistance.
Anderson, D. M. 1980. ?1?('("(s of temperature wndil.loning (In
de\'c!opme'lll and germinatioll of G/)//.~?tltllll,\ Imllllrt'lui,1 (Di?
[lophy<:eae) hypno1.ygotes. j. Plwol. 16: 166-72.
Andersun, D. M. 8.: Morel. f. M. M, 1979. The M'f'ding of t\\'u
red tide blooms by tht? germinali.m of benthic GOII.Wlt/lux
IUlllllrt'lI:li, hypnocpl5. E.,IIU/rine COfl\(al .Hrlr. Sn. 8:279-93,
Andersun, D. M. 8.: Wall. D. 1978. Potential importance of ben?
thic cysts of GUIIYllu/ax 1/l1Iwrnais and G. ".wut'IlIIJ in initialing
toxic dinoflagellat(' blooms. j. Ph.\'tol. 14:224-34.
Bibby, B, T. 8.: Dodge.]. D. 1972. The ellrystmenl (If a fresh?
water dinotlagellau~:alight and electron-mirrosmpit'al Mud)'.
Br. P/ry(l){. I 7:85-100.
Borgert. A. 1910. Kt'rn? and Zdlteilullg bei marinen Ceratit'n?
Arten. :\1"(11. P",li.'(I',tkt/. 20: 1-4t:i.
Cai) Vien, M. 1967. Sur I'existence de pht'nomi'ne~st'xuels dwz
un peridinien libn-. I'AmflhulilllWIl far/at. C. R. H,'bd, S~a1lCf5
lJ,md. Sci. Sa. [) S(i Nat. 264: I006-8.
-- 1968. Sur la germinal ion du zygote el sur un modt' par?
tJculier d" multiplication vegetative (hc7 Ie p.'ridinicn [ibn'
?.lam/,hl/futrum rarll'ri, C. R. up/uJ. S,'nlru, ..1?(l(J. Sn Sa. D, SrI.
'vat. 2r37:701-3.
Chapman, D. V., Dl)dge, J. O. & Heant'y. S. I. 1982. CVSl I'm?
mation in the freshwater dinoHagdlatt' CI'fIJII(lm II/nmdil[,>/flt
(Dinophyceaf'). [>h,wulrJgill 18: 121 ~9,
Chapman, D. V., Living:ilone. D. & Dodge?./- D. 198 L An elec?
tron microscope study of the excystment and early de\'el?
opment of tht? dinoflagellate CfI"rlllUI1l Jllrwu/illflill. Dr. Phyrol.
j. 16:183-94.
Coal.~. D. W. & Ht>inookel, J. F. 1982. A study nl" reprorluction
and other Iil"e cyde plwnomt'n3 in planktonic protists using
an acridint;" or-lIlgt' Huorescencl' technique. Mil,.. Bi/ll. (B",./.)
67:71~9.
Dodge. J. D. J963. The nudeus and nuclear di ... isirll1 in the
Dinophyceae. Arch. Protistmhd. 106;442-52.
Galigber. A. E. & KOlloff. E. 1'<. 1971. [:sUlllilJ/, ,1 Pmrllfld '\-11'
crQ(Uhlll!(IU. 2nd ed. Le-.I. and Febiger, Philadt'lphia. 531 pp,
Guillard. R. R. L. &: Ryther,J. H, 1962, Studies of marin/" plank?
tonic dialom~. I, C.\?r/",..tfllulttlll Jtustedt and D"'oul/la nmfrr.
]?Il ..~a ((;Ie...,,) Gran. CU,I. J. .\Ji<:TQl>i,,1. 8:229-39.
Hulburt. F.. M. 1957. Tht' taxonomy ofunarmOl't"d Dinoph}'('('ae
of shallo..... embaymt'l1ts on Cape C:od. ~assacll\uetls. Bull.
Bull. (W"ad.? 1I0fO 112: 196-219.
ParduCl, B, 1967, Ciliary mO\'ement and coordination in ciliat('s.
1111. Rn.?. Cw~J. 21 :91-128.
Pfiester, L. A.' 197~. Sexual reproduction of PrrulmlU1Jl ,;lIl"lu/II
f. IT/.'oplll,/U/ll (Dinophyceae). j. Ph.,'m/. I 1:259-65.
-- 1976. Sexual reproduni')TJ uf PI'r"Ji"ilwlwi/Jfl (Oinophr?
ccae). j. PhmJI. 12:234~8,
-- 1977, Sexual reproou<:tiol1 of PnidillitHII gll/llIlt"'.'" (Oi?
nnphyfcae). j. Ph)",?"I. 13:92~5.
Pfie51er, L. A. & Anderson, D. M. 1984. DilloflaKdlate life 9'de~
and their environmental ccHllmJ.lt, Ta~?lor. f.J. R.IEd,1 Th,'
Bi"lrig)"if I/.( Dir"'flllf~dll1/('.\. Blackwell Scientific Publications,
Ltd.? Oxford, (in press).
Skoczylas. O. 1958. l:ebcr dit, MiloSf' Hili Ca(l/IIIIII mrmstulII und
einigen ande-ren ?eridinieen. ,41'& Protlll...llrd. 103: 19:1-228.
SEXUAL PROCESSES IN GrRODlXn'M 361
Spf'~?tor, D. L., Pfiester, L.. A. & Trit?mer. R. E. 1981. Ultra?
slrunure of the diT1Clflagellat", Prndiijl'lW' (inrtutll r. I1l'nl'/'"
?m1/!. 11. Light and e1enrun micrust:opic obsen'at.iuns on fer?
tilization. Am. j. BM. 68:34-43.
TufTrau. M. 1967. Perfeniollnt'rnentset prdtiquf'dt'la lechnitfue
d'impregnation au protargol dt?s infusoires cilies. Pru/i,llil",
gu" 3:91-8,
Turpin. D. H., DolH:-1. P. F.. R. &: Ta~?lnr, F. J. R. 1978. St'xualiry
and q Sl filrmat ion in PadIiot rai liS ufthe lOX ic di no Iia gella te
GD11}(W/(/X Ifl11wrrJl,j,. j. Pltyro( 14:235-8.
Tyler,M.A.,Coats.D.W.&Andf'rsoll.D.M, J982. En{,\,slm~nl
in a dynamiC' ('nvirO/unen!: dt'p'lSitiull of dinofiagt'll~le('~'SlS
b}' a Irollial convergencf'. Alar. Eml. Prog. Sn. 7:163-78.
\"lin SloSt:h, H.?A. 1964-. Zum Pl'Ublem cler sl'xllt'llen Furtpflall'
wng in cit'f P~ridineengal.tLl1lgCrmlill/1/, Hrlgu/. Wi." . .Hu?
rUlI1l1rn. 10:140-52.
-- 1965. Sexualitat bei Crm/rum conlulum? .\'fJlltru}J'j~n"dl{ljl?
Til 52; 112-3.
-- 1972. La signification cywlogique cit' la "C'ydnse IlU?
di:aire" dan~ Ie.' erelt' elf' \'ie dt's dilloH;lgl'lli~. Mrlll. S'/L Bill.
Fr. 1972:201-12.
j. Ph~'cDI. 20,361-368 (1984)
-- 1973. Obsel'V;llions on H'Kelalive reprudunion ,HId Sf'X'
ua[ lifecydes of IWll fresll\..aref dinuflal'l"ellatn, Gym,ro,lillium
p.,,,u,/"!)(II1lJITt' and Wa/rJ>~YI,kill 11/Jimla/a sp. nov, 8r. Ph}(ol.
j. 8: 105-34,
Walker. L M. 1982. E\-idenct" for a sexual cycle in the Florida
n~d tide dinoflagellate, P('i<'h"di;cU< brt>t?l.i (=G_WlltIotlIIltUm b"~'f')'
TTflIH. Alii ..'vlICTO.\t. Soc. 101:287-93.
Walker, L. M. & Steiding~r. K. A. 1979. S(~xual reprudunioll
in lh(' loKi,? dinoflaW'llate (;rlIlyJII/IIX mOlll/iJ./a j. Ph)wl. Ei:
312-5.
Wall, D. & Dale, B. 1968. Mnc1ern dinolbgdlalf' "p15 and evo?
lution of thf' Peridiniale5. Mirmplllm/lIt,log;i 14:265-304.
Walanabe, M. M., Watanabe, M. & Ful<.u~?o. Y. 1982. El1l:yslme11l
and f'xcptment of red lide flagellates, L [nclu(!ion of en?
('yMnH'Ul of Sm!,/wdltJ IrocJlOldra. Nat.. (Jpll.) l11sL Environ.
Swd., Res. Rep. :'\io. 30: Eltlr,.plura/iml fmd [{cd Tid~; HI tlte
Cn(/.,f/ll Mal'ltlc Elwhow'U?'II. pp. 27 -42.
Zingmark, R. G. 1970. Sexual rf'prUdU('liol1 in lht' dirlOHauellate
.Vorll/rH?11 mi/lllri.\ Suriray. j. Phyn>l. 6; 122-6.
OBSERVATIONS ON NORTH AMERICAN GO,\IPH01I./E/S (BACILLARIOPHYCEAE).
I. VALVE ULTRASTRUCTURE OF G. AVtAIMILLA WITH COMMENT ON THE
TAXONOMIC STATUS OF THE GENUSJ.2
John P. Kociolf'R and Ba 1'1)' H RO.H'I/.~\??l
Great Lakes ReSt'art'l1 Di\'i~ion, The Uni\'t'nil)' of Midligan. Ann Arbor. Michigan 48109
ABSTRACT
RpCi'nl qUl's!iOl/.S ronunlinK Ihl' taxonomic Jlatus of tIll'
din/um genw Gomphoneis Clrt'/' haVf jJl'Ompll'd ai/iral
exami/wliOlI oj Ihe mh'nr mOll)holof!J' oj a species ol'igi?
nail)' inrluded ill Jhe gPl/l1.\. Light (lnd fleftrotl mi(ro.~l'Oj)if
o/wm.'alioll.l Oil G. mammilla (Elrr.) C/. shmt l that IIU'
charartrristio put forth b)' Cl",'E' to dl'linratf Ihl' gnws
ar/' /Jresl'Ill ill tlti.. taxon. Striaf com/Jasnl of two mu's oj
sImpl/' arl'ola.e lorall'd in d('pl'I'Hion"~ on thr <'a/;'I' and
longitudinal line.~.fim"nl II.'? (J hroad inlel'1!al f1xial/)lall'
lUI'I' ohJPI'7.'l'f1 ill G, mammilla. The Prl'.IPllff oj (-l1.'O apical
spiPH!) ollthi' headpolf' and lllf ,1(l'llctU 1'(' ola hilobi'd apical
jJ(}rr field ll/tnted at the fuol/Nll' are lieu-yilti'd, in addition
to oth.rr valveft'aturl's. \'11/<'1' morpJwlog." (JIG. mammilla
iJ t.:omparE'd wi/II. that 0/ dOl/Uy"punctate Gomphonema
JPUIfJ u,jth the r('sutt thai U'f l'('romml'lUl thl' two f!,nll'ra
I"l'maln Jepamtr.
Ke,l' index u'ol'rh: axial pIalI'; diatomu!tnutruc/uye:
Gomphoneis: Gomphonema: longitudinal tilll'.l; (ax?
OIwmy
I :\rcrpud: n Frlmul1)' 1984.
? Contribution number 382 of I.he Crt'at Lakt,s Rf'search Di?
\?isiOTl.
? Department of Botany. Ohio State Vnh'erlSly, Columbus, Ohio
43210.
? Pr['~en. Address: Departmf'nl of BiololO'. Virginia Common?
wealth l:nh'ersil~', Richmund, Virginia 23284.
The. diatom genus Gomphollei,i was erected by Cleve
in 1894 to segregate forms prtoviously placed in the
genus Gampho/l.l'lna, but which differed in having
striae composed of two rows of puncta (i.e. doubly?
punctate striae) and a shadow line running longi?
tudinally on each side of the axial area (i.e. longi?
tudinal lines). Cleve (1894) originally transferred
three species from Gomplwnnna to Gom/J!wm'ls. mak?
ing the new combinations Gomj/lwlll'iJ I'hga f/S (Crun.)
CL, G. hl'mdeailll (F.hr.) CL and G. 11/(/I1/1l1illo (Ehr.)
CI. Since that timl.'" additional Coml)hotlris taxa have
been described by Schmidt (1899), SkVOrlZOW and
Meyer (1928) and recently by Stoermer (in Reimer
(982).
Observations with light and electron microscopy
have revealed species in the genus Gompluml'ma which
also possess doubly-punctate striae. Hustedt (1942)
described G. inlt'l'medium as possessing striae com?
posed of twO rows of pun(:ta. Studies using electron
microscopy have shown that taxa such as G. olit'rlceu/lt
(Lyngb.) Klitz. (Drum 1969, Helmcke and Krieger
1953. Dawson 1974), C. fjuadripulI((atum (0str.) WisL
(Dawson 1974) and C.curlam (Lange~Berlalot 1978)
also have this characteristic. Striae characteristics
led Dawson (1974) and Lange.Bena!o( (1978) to
transfer these taxa to the genus Gom/)lIoIlPiI.
A reexamination of the GomphnnfmalGomphonl'is
question by Lange-Bertalot (1980) led him to sug-