THE FOUR-CELLEDSPECIES OF GONIUM", 2
JANET R. STEIN
ABSTRACT
STEIN, JANET R. (U. California,Berkeley.) The four-celledspecies of Gonium. Amer. Jour.
Bot. 46(5): 366-371. Illus. 1959.-A review is given of the 4-celled species of Gonium 0. F.
Muller 1773 (Volvocales). From a study of clonal isolates, it has been possible to distinguish
2 distinct species, G. sociale (Dujardin) Warming 1876 and G. sacculiferum Scherffel 1904.
The formermay be divided further,on the basis of vegetativemorphologyand sexual reproduction, into 2 varieties: var. sociale and var. sacculum var. nov., and a possible third variety,var.
majus Hansgirg 1888. A brief discussion of morphologyand sexual reproduction (reported for
the firsttime in G. sociale var. sacculum and G. sacculiferum) is presented as is a key to the
species and varieties.
celledspeciesof Goniurm.
He was aware of Warming's workbut chose to call the alga G. tetrasA.
Braun because Braun,as earlyas 1847, had recognized the 4-celledalga as a species of Goniun. In
1888 Hansgirgplaced G. tetrasA. Braun ex Cohn
1877 in synonomywith G. sociale (Dujardin)
Warming1876. As recentlyas 1902, the invalid
nameG. tetraswas stillused by someworkers(e.g.,
Snow,1902).
Even thoughWarmingrecognizedthe 4-celled
alga as an autonomousspecies,he thoughtit not
unlikelythatit was a stagein thelife-history
of the
16-celled Gonium pectorale 0. F. Muller 1773.
Since Warming'spublication,it has been shown
thattheredefinitely
is a 4-celledspecies (Hansgirg,
1888; Migula,1890; Chodat,1894; Lemmermann,
1897; Pascher, 1927; Smith,1930; Starr, 1955;
Pocock, 1955) as well as a 4-celleddevelopmental
stage of G. pectorale. This developmental
stage is
thegermcolonyproducedby meiosisduringgermination of the zygospore(Schreiber,1925; Stein,
1958b).
HISTORY.-Themost familiar4-celledspecies is
In 1896, W. and G. S. Westdescribeda 4-celled
Gonium sociale. As early as 1841 Dujardin de- Gonium-like
alga as a newgenusTetragoniun,with
scribed a 4-celledmotile colonial alga which he the single species T. lacustre; but G. S. West in
named Cryptomonas(Tetrabaena) socialis. He 1904 placedthespeciesin Gonium.Pascher(1927)
thoughtthatit mightbe a speciesof Goniurn(sensu did not considerG. lacustrean autonomousspecies
Ehrenberg,1838) but the colonyappearedto lack and placed it in the speciesG. sociale. The Wests
a sheathand each of the cells seeminglypossessed believedthattheirorganismwas a different
species
only I flagellum.Braun in 1847 (according to because the 4 cells divergedmarkedlyfrom one
Cohn, 1877) and in 1875, Freseniusin 1856, and anotherand the long flagella(2 per cell) vibrated
Archerin 1865 also noted a 4-celledGonium-like onlyat theirtips owingto the presenceof a thick
alga, but Warmingin 1876 was the firstto referit gelatinousmatrix. Korshikov(1940) in studying
to the genus Gonium. In his notes,Warmingre- coloniesof G. sociale notedthatin his materialthe
ferredto the alga as G. quadrijuga, but, aftersur- matrixsometimes
was quitethick.He believedthis
he concludedthatthe organ- to be the resultof environmental
veyingthe literature,
conditions,possisocialis bly low pH. The divergenceof the cells of the
ism describedby Dujardin as Cryptomonas
was identicalto his manuscriptspecies. He there- colonyof G. lacustre probablyis not a significant
G. sociale (Dujar. enough characterto warrantrecognitionof this
foremade thenew combination,
din) Warming.
taxon as an independentspecies,althoughit may
In 1877, Cohn publisheda descriptionof a 4- represent
a varietyof G. sociale.
The second4-celledspecies,Goniumsacculiferum
December4, 1958.
'Receivedforpublication
Scherffel1904, is less well-knownand there has
2 This studywas startedat Indiana University,
Bloomington, while the author was the holder of the Fanny Bullock beensomediscussionas to its validityas a separate
entity.Chodat(1894), who originallyillustrated
WorkmanFellowship awarded by Wellesley College.
it,
366
IN
THE
COLONIAL
volvocalean
genus Gonium
0. F. Muller,the cells are arrangedin a square,
slightlycurvedplate. The coloniesconsistof 4, 8,
16, or 32 cellswiththenumberusuallyconstantfor
a givenspecies. Since colonieswith8 or morecells
sometimestend to fall apart,at timesforming4to recognizea
it is oftendifficult
celled fragments,
true 4-celledspecies withoutfirstmaintainingthe
alga in clonalculture.The presentstudywas undertaken with the purpose of establishingwhether
criteriaexistwherebythese4-celledspeciescan be
delimited.
At present,two 4-celledspecies of Goniumare
recognized:G. sociale (Dujardin) Warming1876
Scherffel
1904 (fig.
(fig. 1-4) and G. sacculiferum
sub-divided
5-8). Goniumsociale has been further
into severalvarieties.The cells of all the 4-celled
taxa containa singlebowl-shapedchloroplastand
generallya singlepyrenoid,a small anterioreyespot,2 anteriorcontractilevacuoles and 2 flagella
thatarise on eitherside of an anteriorpapilla.
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May,1959]
367
STEIN-GONIUM
2
Pascher (1927), who probablynever observedit,
and Smith(1930), who may or may not have seen
it,all have consideredit to be a growthor developmentalstageof G. sociale. However,whilestudying
livingmaterialScherffel(1904), Conrad (1937),
TABLE 1. Source of cultures of 4-celled species of Gonium
Species
G. sacculiferum
Strain
number
70.5
123a
Fig. 1-9.-Fig. 1, 2. Gonium sociale var. sociale. ca.
X500.-Fig. 1. Side view.-Fig. 2. Polar view.-Fig. 3, 4.
Gonium sociale var. sacculum var. nov. ca. X800.-Fig. 3.
Side view; note presence of parental cell wall or sac at
base of colony.-Fig. 4. Polar view, showing 1 cell wall
connectionat upper right.-Fig. 5-8. Goniumsacculijerum;
fig. 5, 6 ca. X800; fig. 7, 8 ca. X 1250.-Fig. 5, 7. Side
view; note presence of parental cell wall, or sac.-Fig. 6,
8. Polar view.-Fig. 9. Gonium sociale var. sacculum var.
nov. ca. X725. Living zygospores showing reticulate cell
wall; zygosporeat right showing only 1 pyrenoid,optical
section; left zygospore showing wall reticulations,surface
view. All photographsfromliving material; fig. 1-8, colo.
Locality
P. Biebel INDIANA, Brown
Pond
near Yellowwood
Reservoir Dam.
TA,
R. Norris M I NNESO
Clearwater County: Pond on Twospot Trail, '/2
mile west of Middlewest trail;
Itasca State Park.
J. Stein CALIFORNIA, Solano
County:
Roadside ditch,
41/2 miles north
of US Highway
40 on road north
of Green Valley
Country Club.
.6a"County:
.7 a
.13a
76
G. sociale
var. sociale
Collector
Cam7a
R. Starr ENGLAND,
Jesus
(IU No. (& isolator) bridge:
Creek on grounds
14)
of Jesus College.
J. Stein ILLINOIS, Douglas
71
County: Pasture
runoff, 5 miles
south of Tuscoloa
on west side of
US Highway 45.
R.Norris MINNESOTA,
75
Clearwater County: Pond on Twospot Trail, Y2
mile west of Middlewest Trail;
Itasca State Park.
8a
M. Hart- GERMANY, Berlin
(as G. tetras
mann
(IU No.
(& isolator) Hartmann nomen
197)
nudum)
122.4a
G. sociale
.6 a
var. sacculum
nov.
var.
J. Stein
CALIFORNIA, San
Joaquin County:
Pasture-land de4.4
pression,
miles north of
Clements on east
side of State
Highway 88.
a In Culture Collection of Algae, Indiana University
(IU), Bloomington.
nies suspended in India ink to emphasizegelatinous sheath;
fig.7, 8, courtesyR. C. Starr.
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368
[Vol. 46
AMERICAN JOURNAL OF BOTANY
10~~~~~~~~~~~~~~1
;r9~~~~~~~~~~~~1
~~~~~~~~~~~~~~~
7
18
'
*
15
12
,..~~~~~~~
~~~1
~16
21
2
t <22
var.nov.ca. X1500.-Fig. 10-13. Vegetative
colonies.-Fig.10.
Fig. 10-22.-Fig. 10-16. Goniumsocialevar.saccitlium
Emerging
colonystillattachedto parentalcell wall,or sac.-Fig. 11. Parentalwall thathas been shedby a colony. Fig.
of cell walls,opticalsection.-Fig.13. Colonyshowingcell
formedby protuberances
12. Colonyshowingconnections
wall connections
and posterior
locationof parentalcell wall,side view.-Fig. 14. Fusinggametes.-Fig.15. Planozygote
withreticlatecell wall,opticalsection.-Fig.17-22. Goniumsacculibeforefusionof chloroplasts.-Fig.
16. Zygospore
coloniesshowrelationof cells to parentalcell wall,
ferum;fig.17 ca. X1000; fig.18-22X150Q.-Fig. 17, 18. Vegetative
orsac; notelack ofwall connections
polarview.-Fig. 18. Side view.-Fig. 19. Akinete
betweencells.-Fig. 17.Flattened,
beforefusionof chloroplasts.-Fig.
withreticulate
wall; notepresenceof only1 pyrenoid.-Fig.20. Planozygote
21, 22.
culture(No. 76); fig.22. Formed
Zygospores
withreticulatecell walls,opticalsection.-Fig.21. Formedby homothallic
culture(No. 70). (All drawingsfromlivingmaterial.)
by heterothallic
otherwisenoted,all isolationswere made by the
author. The clones were maintainedin Pringsheim'ssoil-water
medium,withor withoutthe addition of calcium carbonate (Starr, 1956), at
18.50C. ? 1.50, on a 16-hr.light-8-hr.
darkcycle.
During active growththe culturesreceivedabout
200-300 ft.-c.intensity
of light; stockculturesreceived about 75 ft.-c.intensity.Transfersof the
stock cultureswere made every2 mo., and optimal growthoccurred7-14 days aftertransferto
new medium. It was duringthis time of optimal
growththatthe observationswere generallymade
and thatculturesof compatiblematingtypeswere
mixed. To establishwithcertainty
the presenceof
a gelatinoussheath,colonieswereplaced in a drop
MATERIALSAND METHODS.-The techniques used of India ink on a microscopeslide and observed
to secureclonal culturesfromfieldcollectionshave withthelightor phase contrastmicroscope.
OBSERVATIONS.-Starr
(1955) studied sexual rebeen fullydescribedby the author (Stein, 1958a,
1958b) with regardto othercolonial Volvocales. productionin Goniumsociale and noted that his
The clonesstudiedare listedin table 1, and unless isolate was homothallic,producingnaked isogam-
Korshikov (1938, 1940) and Skuja (1955) have
recognizedit as a separatetaxon. Skuja considered
it differentenough to erect for it the genus
Basichlamys.
In Goniumsacculiferum,
the4 cells of thecolony
are held togetherby the parentalcell wall and by
the presenceof the gelatinousmatrix.The cells
themselvesare not connectedone to anotherby
protuberances
of thewalls,as in all otherspeciesof
Gonium,includingG. sociale. This connectionof
thecell walls,is a characterincludedin thegeneric
diagnosisas emendedby Prescottet al. (1949), although not mentionedin either 0. F. Muller's
(1773) originaldescription,
or Ehrenberg's(1838)
emendation.
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May, 1959]
STEIN-GONIUM
369
enoughto justifygivetesthatfusedto forma planozygotewhichsettled not appear to be significant
between
down,becominga zygosporewitha reticulatewall. ing themvarietalstatus. The differences
It has been possible in this studyto confirmhis G. sacculiferum and the 2 varieties of G. sociale
usingthesameisolate (No. 7) as well (var. sociale and var. saccu,lum) are marked
observations,
as twoothers(No. 71, No. 75). Since Starrdid not enough,however,to justifyrecognitionof G. sacit culi/er-um(fig. 5-8, 17-22) as a separate species,
discussthe fateof the pyrenoidsor chloroplasts,
should be notedthat in the planozygotethereare but not as a separategenus,in the opinionof the
2 chloroplasts
whereasin the ma- presentauthor.
and 2 pyrenoids,
turezygosporeonly 1 chloroplastbut 2 pyrenoids The culturecollectionof algae at Indiana Unia versitycontainsanother4-celledcultureof Gonium
are present. During the presentinvestigation,
clone was also obtained (No. 122). (IU No. 197) whichwas isolatedby Max Hartmann
heterothallic
clone also produces isogametes and purifiedby HerbertMeyer (Starr,1956; and
This heterothallic
zygospore(fig. personalcommunication).
thatfuseto forma reticulate-walled
Hartmanncalledthisor9 14-16) ; however,thereis a slightvariationin ganismG. tetras,but no descriptionof it can be
theformof thevegetativecolony. The parentalcell foundin the literature;also, the binomialis prewall generallyremainsattachedto the gelatinous emptedby G. tetrasA. Braun ex Cohn 1877. The
rnatrixof the new daughtercolony,trailingbehind alga in questionis morphologically
quite similarto
thecolony(fig.3, 10, 13). UnlikeG. sacculiferum, thetypicalG. sociale and is consideredrepresentathecells of thecolonyare connectedto one another tiveof G. sociale var. sociale.
of the cell walls (fig.4, 12, 13).
by protuberances
Hansgirg (1888) describeda smallerform of
As the retentionof the sac is quite consistent,it Goniumn
sociale as G. sociale var. majus. This vaseems desirableto recognizethis taxon as a sepa- rietyhas not subsequentlybeen collectedand its
rate variety,G. sociale var. sacculum(fig. 3, 4, 9, statusis uncertain.
10-16). The homothallicform,lackingthe sac, is
A keyto theknown4-celledspeciesand varieties
the typevarietyand shouldthus be knownas G.
of each are as follows:
and a description
of
sociale var. sociale (fig. 1, 2). It is this latterva- 1. Gonium
Cell walls connected with one another; parental wall
in
rietythatis probablymoregenerallyencountered
presentor absent; cells ovate, colonies brightgreen,the
collections.However,Smith (1930) probablyobsociale 2
cells compact-G.
servedthenewvarietyin materialcollectedin Cali- 1. Cell walls not connectedwith one another; parental wall
fornia.
As mentionedpreviously,the retentionof the
parental sac is also characteristicof Scherffel's
whichprobablyhas
species,Goniumsacculiferum,
often been confused with G. sociale var. sacculuin.
always present; cells elliptic-elongate; colonies pale
sacculiferum
green, the cells spreading-G.
2. Parental ivall never present in daughter colonies;
sexual reproduction,as far as known, homothallic
--------------------------------G. sociale var. sociale
2. Parental wvallpresent in immaturecolonies, present
or absent in dividing colonies; sexual reproduction,
as far as known,heterothallic
-----------------------------G. sociale var. saccculum
GONIUM sacculiferumScherfiel (1904) (fig. 5-8.
collectedin IndiClonal culturesof G. sacculiferum
ana, Minnesota,and Californiahave been isolated
and studiedto determinethe statusof this taxon.
Skuja's (1955) main reasonforerectingthe genus
Basichlamyswas the lack of wall connectionsbetweenthecells,thecellsbeingheldtogetheronlyby 17-22). Basichlamyssacculifera(Scherfiel)Skuja
the parental sac and the envelopinggelatinous (1955): B. sacculifera var. rhomboidea Skuja
matrix(fig.5, 7, 17, 18). Since thecellsare notat- (1955).
tached to one another,the colony appears more
Description.-Colonies11-42, in diameter,pale
spread-outand thecellsfartherapart (fig.6, 8, 17, green, consistingof 4 cells always enclosed by
18); however,the vegetativecells of G. sacculi- gelatinousmatrix,or sheath,withprobablecentral
than those of G. opening; cells not connectedto one anotherby
feritmare more elliptic-elongate
sociale and, therefore,
the entirecolonyis smaller. protuberances
of cell walls but ratherheldtogether
to sac-likeparentalcell wall and
The Indiana isolate (No. 70-series) of Gonium bytheirattachment
isogamous and pro- by surroundinggelatinoussheath; cells ellipticsacculiferumis heterothallic,
ducesreticulate-walled
zygospores(whichat maturi- elongate,9-18, long by 4-13 ,uwide,containinga
ty contain1 chloroplastand 2 pyrenoids,fig.21) bowl-shapedchloroplast,1 pyrenoid,anterioreyein exactlythesamemanneras G. socialevar. sociale spot,2 contractile
vacuoles and 2 flagellainserted
and G. sociale var. sacculum (fig. 16). In fact, on eitherside of the anteriorpapilla; in asexual
it is impossibleto tell reproduction,all cells dividing at approximately
duringsexual reproduction,
The Minnesotaisolate (No. 76) is the same time to produce four 4-celleddaughter
the difference.
homothallicand also producessimilarzygospores coloniesthatremainpermanently
attachedto trail(fig. 22). This Minnesotaclone and the one iso- ing parentalwall; cells at timesformingreticulateeitherhomolated fromCalifornia(No. 123) readilyproduce walled akinetes;sexual reproduction
akinetes(fig.19) whichresemblethezygosporesas thallic or heterothallicand effectedby naked
to form,but containonly 1 pyrenoidat maturity. isogametesproducingquadri-flagellate
planozygotes
The differences
betweenthese various isolates do that settledown to formzygosporeswith heavy
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370
AMERICAN
JOURNAL OF BOTANY
[Vol. 46
reticulate
walls; germination
ofzygosporeuniknown.by gelatinousInatrix,or sheath,usuallywithouta
Distribution. In UnitedStates (Indiana,Minne- centralopening;cells connectedto one anotherby
sota, California) in fresh-water
ponds,pools, tem- protuberancesof cell walls; in immaturecolonies
poraryroadsideditches.Also reportedfroma pond cells held togetherby parentalcell wall which at
is separatedfromthe cells but is retained
in theBotanicGarden,Budapest,Hungary(Scherf- maturity
fel, 1904); Karsee, Alps, Switzerland(Conrad, in gelatinousmatrix;cells ovoid, 11 It long by 9 tu
1 pyre1937); Kovda, near Kharkovin Karelia District, wide,containinga bowl-shapedchloroplast,
vacuoles,and 2
and Biological Station, Gorki University,Gorki noid,anterioreyespot,2 contractile
District, Ukraine (Korshikov, 1940); Abisko, flagellainsertedon eitherside of anteriorpapilla;
in asexualreproduction
all cellsdividingat approxiSwedish-Lappland
(Skuja, 1955) .
matelythesametimeto formfour4-celleddaughter
GONIUM sociale (Dujardin) Warming (1876)
coloniesthattemporarily
remainattachedto trailvar. sociale (fig. 1, 2). Cryptomonas
socialis Du- ing sac-likeparentalcell wall; sexual reproduction
jardin (1841): GoniumtetrasA. Braun ex Cohn heterothallic,
as far as knownl,and effectedby
(1877): TetragoniumlacustreW. & G. S. West nakedisogametesproducingquadri-flagellate
plano(1896): Goniumlacustre(W. & G. S. West) G. S. zygotesthat settledown to formzygosporeswith
West (1904): G. tetrasHartmannnomennudum heavyreticulatewall; germination
of zygosporeun(Indiana UniversityNo. 197, CambridgeUniver- known.
sityNo. 32/3).
Type in HerbariumUC; also in CultureCollecDescription.-Colonies 20-48 /u in diameter, tionof Algae,Indiana University.
brightgreen,consisting
of 4 cellsgenerallyenclosed
Distribution.-Typelocality:a temporaryfreshby gelatinousmatrix,or sheath,withor withouta waterpond on pastureland in San Joaquin
centralopening; cells connectedto one anotherby California,4.4 mi. northeastof ClementsCounty,
on
of cell walls; cellsovoid,9-22, long side of StateHighway88. Also collectedby G.east
protuberances
by 5-16 /A wide, containinga bowl-shapedchloro- Smith(1930, p. 367) from"outdoorgold fish M.
pool
plast, 1 or 2 pyrenoids,anterioreyespot,2 con- at the home of Prof. J. I. W. MacMurphy[Palo
tractilevacuoles,and 2 flagellainsertedon either Alto, California]." Future studieswill probably
side of theanteriorpapilla; in asexual reproduction showthatthisvarietyis widespread
throughout
the
all cells dividingat approximately
thesame timeto world.
formfour 4-celledcolonies that completelybreak
awayfromtheparentalcolony;sexualreproduction GONIUM
sociale (Duj ardin) Warmingvar. majus
homothallic,
as faras known,and effected
by naked Hansgirg(1888, p. 105) .
isogametesproducingquadriflagellate
planozvgotes Description.-"Veget. Zellen vor der Theilung
that settle down to formzygosporeswith heavy meist15 bis 18 /A,
seltenerbis 21 ,udick,fastkugelreticulatewall; germination
ofzygospores
unknown. rund oder eif?rmig,am vorderenhyalinenEnde
undmit2 Cilienversehen,
Distribution.-Cosmopolitan
in temporary
fresh- kurzzugespitzt
Pyrenoide
waterponds and lakes, oftenin pools on pasture 4 bis 6 /ugross (sonstwie die typischeForm.).`'
land or in those receivingdrainagefrompasture
Distribution.-". . . bisherblos in den Schranzland.
grabenhinterdemgew. Kornthor1885 im November massenhaft,das Wasser schmutziggrin farGONIUM sociale (Dujardin) Warmingvar. sacbend! "
culum var. nov. (fig.3, 4, 9, 10-16).
Description.3-Colonies 20-40 / in diameter, Species excludenda.-Gonium tetrasphaerium
brightgreen,consistingof 4 cells always enclosed Schrank1803 - Euastrumsp.
GoniumtrichinaPritchard1834
Scenedesmus
'The Latin description
was preparedby Dr. Hannah sp.
Croasdale.
DEPARTMENT OF BOTANY
GoNIUMSOCIALE (Dujardin) Warmingvar. sacculum
UNIVERSITY OF CALIFORNIA
var nov.
BERKELEY 4, CALIFORNIA
Coloniae 20-40,u diam. nitido-viridesconstantese
quattuorcellulis,matricevel vaginagelatinosa,plerumque
LITERATURE CITED
sine apertura centrali,semper inclusis; cellulae per
ARCHER,W. 1865. In Minutes of Dublin Microscopical
protuberantias
e membranisconnexae; cellulae coloniClub, 16 March 1865. Quart. Jour. Microsc. Sci. ser.
arum immaturarum
per membranam
parenteminter se
2, 5: 234-235.
coniunctae,
in coloniismaturisa cellulisseiuncta
membrana
sed in matricegelatinosaretenta; cellulae coloniarum BRAUN, A. 1875. In Sitzungs-berichtder Gesellschaft
11,ulong.,9 Itlat.,ovatae,chloroplastum
maturarum
crateriunumpyrenoideum,
formem,
duas vacuolas
stigmaanterius,
contractiles
et duo flagella,
utriquelateripapillaeanterioris nudos, planozygotumquadriflagellatumproducentes,effecta,
inserta,continentes;
per reproductionem
asexualemomnes planozygotumquiescit ad zygosporam,membrana crassa
cellulae, ad quattuorcolonias-filias
quadricellularespro- reticulataquepraeditam,formandam;germinatiozygosporae
ducendas,quasi simul se dividentes,coloniis-filiabus
ad ignota.
membranam
cellulae parentisvesiculiformem
Typus in Herbario Univ. Californianae; cultura type in
quae post
coloniamtrahitur,
temporaliter
adhaerentibus;
reproductio collectione culturarum algarumnUniv. Indianana, consersexualis,quantumsciripotest,heterothallica,
perisogametas vatur.
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May,1959]
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A. A. 1938. Volvocineae. In Viznachnik
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E. 1897. Beitrag zur Algenflora von
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