PHYCOLOGIA
Lloydiella, a
new
10(1), 1971
genus of the Zygnemaceael
A. AHMAD AND M. E. GOLDSTEIN
Botany Department, McGill University, Montreal, Quebec, Canada
Accepted September
28,
1970
The new genus an� species Lloy�iella kankensis was isolated into culture from a dried mud sample col­
l�cted at Kanke, �I}dla. The vegeta�lve and se�ual morphology were described in detail under controlled en­
vlronm�ntal c.ondltJo�s. The .genus IS characterIzed by the presence of two axile plate-like plastids per cell with
pyrenOlds as In certa�n species of Moug�otia . .With. respect to conjugation, Lloydiella lacks specialized features
such as progam�tanglal cells, cytoplasmiC residue .In gam�tangia following plasmogamy, a gelatinous sub­
stance surroundL�g zygospores, and a zygosporanglUm .as In .Mougeoti.opsis. The characteristics of Lloydiella
are com'p�red with othe.r genera of Zygnemaceae with axtle plate-hke plastids and the species Lloydiella
kankensls IS compared with other species of the family.
Phycologia, 10(1):
1-6
(1971)
Introduction
In the first monographic treatment of Zy­
gnemaceae, Transeau (1951) recognized 13
genera in the family. In two succeeding mono­
graphs of Zygnemaceae, Randhawa (1959)
and Gauthier-Lievre (1965) recognized the
same genera as Transeau. However, following
a detailed study of the types of gametes and
zygo�pore formation primarily in Japanese
species of Zygnemaceae, Yamagishi (1963)
proposed a revised system of classification for
the. family which included 15 genera, ten of
which were recognized by the above authors.
The ten genera were Mougeotiopsis Palla De­
barya Wittrock, Mougeotia Agardh, Te'm no­
gametum W. and G. S. West, Sirocladium
�andhawa, Spirogyra Link, Sirogonium Klitz­
mg, Zygnema Agardh, Zygnemopsis (Skuja)
Transeau, and Zygogonium Klitzing. With re­
spect to the remaining three genera: Pieurodis­
cus Lagerheim was placed in synonomy with
Zygogonium, Hallasia Rosenvinge was includ­
ed i� Zygnemopsis, and Entransia Hughes was
conSidered of doubtful taxonomic status. The
five addi�ional genera recognized by Yamagishi
(196�) mclude Gonatozygon de Bary, Geni­
cuiana de Bary, Temnogyra Lewis plus two
new genera Mougeotiella Yamagishi and Neo­
zygnema Yamagishi. More recently Bourrelly
lInvestigation supported by the National Research
Council of Canada.
(1966), in his taxonomic treatment of the
green algae, recognized 12 of the 13 genera of
Transeau (1951). Like Yamagishi (1963),
Bourrelly placed the genus Hallasia in synon­
omy with Zygnemopsis and expressed doubt
about the taxonomic status of Pieurodiscus and
Entransia. With respect to Temnogyra ' Mou­
geotiella, �nd. fl! eoz�g,!ema, Bourrelly doesn't
regard their dlstmgUlshlllg features as important
enough to w�rrant their taxonomic recognition.
Thus, accordmg to recent taxonomic treatments
of t� e Zygnemaceae, at least 18 genera are rec­
ogn.lzed and distinguished primarily on the
baSIS of chloroplast structure and certain fea­
tures of the conjugation process.
Until now all of the existing genera of the
Zygnemaceae have been described on the basis
of studies of natural collections. In the course
?f isolating numerous clones of Zygnemaceae
III culture from mud samples collected in India,
the au�hors were unable to identify one clone
a.ccordlll� to the existing taxonomic descrip­
!lOns. With respect to its vegetative morphology
It pos�essed two . axile plate-like plastids per
cell With pyrenolds as in certain species of
Mouge<:tic:. However its sexual morphology was
mos� s�mllar to Mougeotiopsis in lacking the
speCIalIzed features of conjugation found in
Mougeotia, Mougeotiella, Debarya, and Tem­
nogametum. Following a detailed study of the
vegetative �nd sexual morphology under con­
trolled envlfonmental conditions, it was found
AHMAD AND GOLDSTEIN: Lloydiella
PHYCOLOGIA, VOL. 10(1), 1971
female gametangia and not enclosed in zygo­
sporangia.
to possess a combination of characteristics un­
like any described taxon in the Zygnemaceae.
Therefore, the purpose of this paper is to pre­
sent the description of the new genus and
species Lloydiella kankensis, the genus being
named in honor of the late Professor F. E.
Lloyd of McGill University. The authors wish
to thank Dr. Hannah Croasdale for the Latin
diagnosis.
Filamenta non ramosa; cellulae vegetativae maturae
duos chloroplastos axiales taeniaformes habentes;
omnis chloroplastus aliquot pyrenoidibus dispersis
praeditus; plastides per pontem cytoplasmicum qui
nucleum continet connexae.
Coniugatio scalariformis, anisogamica; protoplasma
totum gametangiorum velut gameta fungitur, ita nul­
IUJIl residuum cytoplasmicum in gametangiis manet:
dissepimenta inter gametangia coniugentia, ad porum
,
parvum efficlendum, per quem gametum masculum
abit� ex; parte dissolvuntur; zygota in gametangiis
femlenels formata, necque in zygosporangiis inclusa.
Materials and Methods
Upon rewetting a dried mud sample col­
lect �d in 1965 from a rice field in Kanke,
IndIa, strain 304 of Lloydiella kankensis was
isolated into culture using a fine glass pipette.
Cultures were maintained in half-pint milk
bottles containing Pringsheim's soil-water me­
dium without CaCOs (Starr, 1964). The light
source consisted of banks of standard cool­
white fluorescent tubes controlled by an auto­
matic clock device to provide 16 hr of light and
8 hr of dark daily. Illumination received was
250 ft-c intensity and the temperature was
maintained at 20 (± 1) C.
Conjugation could be observed in soil-water
medium 8-10 weeks after subculturing, but
could also be induced readily following the
technique of Allen (1958). Filaments from
three-week old cultures were placed in Petri
dishes containing sterile 1.5 per cent distilled
water agar and placed under illumination of
250 ft-c intensity. Within 2-3 days conjugation
was initiated and in 4-6 days zygospores were
formed.
A culture of strain 304 has been sent to the
Culture Co�lection of Algae, Indiana University,
and herbarIum specimens deposited in the Mc­
Gill College Herbarium (MTMG).
L10ydielJa kankensis
sp. nov.
Mature vegetative cells long and narrow,
19-23 f.t wide and 140-275 f.t long, with two
ribbon-like axile chloroplasts, connected by a
cytoplasmic bridge containing nucleus; plastids
with several pyrenoids; chloroplasts occupy al­
mos! the whole length of the cell except a small
portIOn on one end of the cell where the va­
cuole is evident.
Conjugation scalariform, anisogamous, ho­
�othallic, dioecious; male filaments fragment
lI� to one- or two-celled (rarely many-celled)
pIeces; female filaments remain intact; develop­
ing female gametangia longer than the male
gametangia and show conspicuous unilateral
swelling prior to contact with the male; male
gametangia geniculate before contact with fe­
male; no conjugation tube formed; entire proto­
plast of the male gametangium migrates into
the female gametangium through a small pore
�ormed betwe�n adjacent walls of the conjugat­
illg gametangIa; zygote formed in the female
ga�etangium and not enclosed in zygospor­
angmm; zygospores spherical to ovoid, bound­
�d by a single wall; wall smooth and yellowish
ill color. DISTRIBUTION: Kanke (Bihar) India.
Strain. ORIGIN: dried mud sample collected
from rice field, Kanke, India, 1965.
Results
L10ydiella
gen. nov.
Unbranched filaments; mature vegative cells
w! th two ribbon-like axile chloroplasts, each
WIth several scattered pyrenoids; plastids con­
nected by cytoplasmic bridge containing nu­
cleus.
Conjugation scalariform; entire protoplast of
gameta?gia serv� as gametes, thus no cytoplas­
. reSIdue left ill the gametangia; the walls be­
mIC
t�een the conjugating gametangia dissolve par­
tially to form a small pore through which the
male gamete migrates; zygotes formed in the
Cellulae vegetativae maturae longae angustaeque
19:-23 fL 1a�., 140-275 fL long. , duos chloroplasto�
aXlales taema�ormes, per pontem cytoplasmicum qui
nucleum co�tJ.net connexos, habentes; plastides ali­
quot pyrenOldlbus praeditae; chloroplasti fere totam
cellulae longitudinem, nisi partem parvam in unam
extremitatem ubi vacuola apparet, occupant .
. Con\ugatio scalariformis, anisogamica, homothal­
hca, dIOeca; filamenta mascula in particulas uni-vel
bicellulares. (rar? multocellulares) se frangunt; fila­
menta femmea mtacta manent; gametangia feminea
evolventia longiora quam gametangia mascula necnon
infiationeI?
unilateralem. manifestam
priusquam
gametangia . mascula .contIgunt praebent; gametangia
mascula gemculata pnusquam gametangium femineum
2
AHMAD AND GOLDSTEIN: Lloydiefla
PHYCOLOGIA, VOL. 10(1), 1971
inclusa; zygosporae sphericae ad ovatus, per singu­
lum stratum membranae definitae; membrana levis
atque subflava . ORIO: Species in exemplo luti exsiccati
ex agro oryzae, in loco Kanke, India dicto, 1965,
lecti.
contigunt; tuba coniugationis nulla; protoplastus totus
gametangii masculi in gametangium femineum per
porum parvum qui inter dissipimenta contigua game­
tangiorum coniungentium formatur abit; zygotum in
gametangio femineo formatum non in zygosporangio
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FIG. 1-6. Lloydiefla kankensis Ahmad and Goldstein. FIG. 1. Recently divided vegetative cell with single axile
plate-like plastid; note nucleus appressed to plastid; X 125. FIG. 2. Mature vegetative cells with two axile
plate-like plastids with nucleus between in cytoplasmic bridge; note vacuole at one end of cells; X 45. FIG. 3.
Swelling of female gametangia in central region prior to contact with male gametangium; X 50. FIG. 4. Early
stage in scalariform conjugation; note the one-celled geniculating male gametangium comes in direct contact
with swollen female gametangium; no conjugation tube formed by either gametangium; X 50. FIG. 5. Later
stage in conjugation; note plasmogamy is physiologically anisogamous; X 50. FIG. 6. Conjugation complete,
smooth single-walled, ovoid zygospore formed in female gametangium; note the absence of cytoplasmic
residue in both gametangia; X 50.
3
AHMAD AND GOLDSTEIN: Lloydiella
PHYCOLOGIA, VOL. 10(1), 1971
portion of its gametangium. Following gamete
fusion the zygote is formed; it is spherical to
ovoid in shape and is bounded by a single
smooth yellowish wall. No cytoplasmic residue
is left in either gametangia after the zygote is
formed. The zygote lies in the female game­
tangium (Fig. 6) and as yet zygote germina­
tion has not been observed.
With respect to vegetative morphology, it
was found that recently divided cells of Lloy­
diella kankensis are almost identical to mature
vegetative cells of most Mougeotia species (Fig.
1). These cells contain a single plate-like axile
chloroplast with several scattered pyrenoids.
The nucleus is located in the center of the cell
to one side of the chloroplast. However, as the
cell matures it elongates and the chloroplast
divides into two. Following division, the nu­
cleus is found in the cytoplasmic bridge be­
tween the two chloroplasts (Fig. 2).
Conjugation is scalariform, homothallic and
dioecious. Vegetative filaments are indistin­
guishable until the process of conjugation is
initiated. The male filaments can be distin­
guished because they fragment into small seg­
ments containing one or two cells, and very
rarely more than this number (Fig. 4). The
male gametangia undergo geniculation even be­
fore they make contact with the female fila­
ments. At this time, the female filaments gener­
ally remain intact and the cells are usually
noticeably longer than those of the male fila­
ments. The developing female gametangia then
swell considerably in the central region, par­
ticularly on the side which will come in con­
tact with the male gametangium (Fig. 3). When
contact is made, a conjugation tube is not
formed by either gametangia, but they are at­
tached directly (Fig. 4). A small pore is
formed in the wall where the two gametangia
meet. The entire protoplast of the two game­
tangia form the two gametes. The male gamete
then passes through the narrow pore into the
female gametangium (Fig. 5) and fuses with
the female gamete which lies in the swollen
Discussion
The genera of Zygnemaceae with axile plate­
like plastids are distinguished by the presence
or absence of the following combination of
characteristics (Transeau, 1951; Randhawa,
1959; Gauthier-Lievre, 1965; Yamagishi,
1963) : pyrenoids in the chloroplasts, progame­
tangial cells, cytoplasmic residue in gametangia
following plasmogamy, gelatinous substance
surrounding zygospores, and a zygosporangium.
Czurda (1932) would disregard these charac­
teristics and place all the genera with axile,
plate-like chloroplasts into the single genus
Mougeotia. However, many notable phycolo­
gists (Fritsch, 1935; Transeau, 1951; Smith,
1950; Randhawa, 1959; Yamagishi, 1963;
Gauthier-Lievre, 1965; Bourrelly, 1966) re­
gard these characteristics as significant both in
the taxonomy and phylogeny of the genera of
Zygnemaceae. Based on the above character­
istics, Table 1 presents a resume of the dis­
tinguishing features of the six genera, including
the new genus Lloydiella, presently recognized
in the Zygnemaceae with axile plate-like plas­
tids.
On the basis of the resume in Table 1 it can
be seen that the last three genera listed are dis­
tinguished by the presence of a single charac-
TABLE 1
Resume of the distinguishing characteristics of the 6 genera ot the Zygnemaceae
with axile plate-like plastids (- characteristics absent; + characteristic present)
pyrenoids
Genera
Cytoplasmic
residue
Zygosporangium
Gelatinous
substance
surrounding
zygospore
Progametangial
cells
Mougeotiopsis Palla
L/oydiella Ahmad and
Goldstein
+
Mougeotiella Yamagishi
Mougeotia Agardh
Debarya Wittrock
Temnogametum W. and G. S.
+
+
+
West
+
+
+
+
+
+
4
AHMAD AND GOLDSTEIN: Lloydiella
PHYCOLOGIA, VOL. 10(1), 1971
to type VI "inflated on conjugating side" pro­
posed Jao (1935). The male gametangia in
Lloydiella do not swell, but prior to contact
with the female gametangia the male filaments
fragment generally into one- or two-celled seg­
ments, geniculate, and make direct contact with
female gametangia, with neither gametangia
forming a conjugation tube. The dissociation of
female gametangia after conjugation is known
in certain species of Spirogyra (YamagIshi,
1963), and fragmentation of both male and
female filaments during conjugation is known
for Zygnemopsis minuta Randhawa (Rand­
hawa, 1959). However, as far as we are aware,
fragmentation of male filaments only appears
to be unique among the Zygnemaceae. Geni­
culation is a common phenomenon in many
species but the absence of a conjugation tube
appears to be known only for species of Siro­
gonium and Sirocladium (Randhawa, 1959).
Lastly, Lloydiella kankensis is physiologically
anisogamous and the zygospore is formed only
in the female gametangium. This is a relatively
common phenomena in many species of Zygne­
maceae, and in fact species of Spirogyra and
Mougeotia are known to be physiologically
isogamous or anisogamous (Yamagishi 1963).
In conclusion, it seems clear that the new
genus Lloydiella is most similar to the mono­
typic genus Mougeotiopsis. Both share similar
sexual characteristics regarded as diagnostic for
the genera of Zygnemaceae, but differ in chloro­
plast morphology, particularly with respect to
the presence or absence of pyrenoids. Support
for the use of presence or absence of pyrenoids
as a generic characteristic is found in the clas­
sification of genera in the Ulotrichaceae (Smith,
1950) and more recently in the study in culture
by Starr (1955) on genera of the Chlorococ­
caceae. According to the recent taxonomic
treatments of the Zygnemaceae, this difference
is regarded as significant and justifies the de­
scription of the new genus Lloydiella.
teristic not found in the other genera. Mougeo­
tiella is distinguished from the closely related
Mougeotia by the absence of zygosporangia,
and Mougeotiopsis is distinguished by the ab­
sence of all the characteristics. Lloydiella, like
Mougeotiopsis, lacks all the above sexual char­
acteristics, but is distinguished from Mougeoti­
opsis by the presence of two axile plate-like
. plastids with pyrenoids. However, there are at
least two species of Mougeotia, M. capucina
(Bory) Agardh, and M. prona Transeau
(Transeau, 1951) which possess similar chloro­
plast morphology to Lloydiella. However, on
the basis of their reproductive morphology, the
species are unquestionably species of Mouge­
otia. Therefore, Lloydiella is easily distin­
guished from the other genera of Zygnemaceae
with axile plate-like chloroplasts.
Evolutionary relationships of the genera
within the Zygnemaceae have been discussed
by several authors (Fritsch, 1935; Randhawa,
1959; Yamagishi, 1963) but we regard the
scheme proposed by Yamagishi as the most
comprehensive and lucid to date. It is not our
wish at this time to discuss in detail the com­
plexities of the evolutionary relationships in the
family, but simply to suggest that Lloydiella,
like Mougeotiopsis (Yamagishi, 1963), ap­
pears to represent a "primitive" generic type
among the genera with plate-like plastids. Both
genera lack the specialized characteristics of
the conjugation process found in the other
genera with plate-like plastids, and therefore
possess the Spirogyra-type of gamete and zygo­
spore-formation (Yamagishi, 1963). The
Spirogyra-type of gamete- and zygospore-forma­
tion is characterized as follows: ordinary vege­
tative cells without cell division form game­
tangia, the entire protoplast of each game­
tangium produces a gamete, the lumen of the
conjugating cells form no gelatinous substance,
and no zygosporangium is produced. Accord­
ing to Yamagishi (1963), the Spirogyra-type
of gamete- and zygospore-formation represents
the simplest mode of conjugation in the Zygne­
maceae.
References
ALLEN, M. A. 1958. The biology oj a species com­
plex in Spirogyra. Ph.D. Dissertation, Indiana
Univ., Bloomington, 240 p.
Lloydiella kankensis possesses interesting as
well as possible unique characteristics among
the species of Zygnemaceae. In the develop­
ment of female gametangia in Lloydiella kan­
kensis, swelling was localized in the central re­
gion primarily on the conjugating side. This
type of development appears to be most similar
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AHMAD AND GOLDSTEIN: Lloydiella
PHYCOLOGIA, VOL. 10(1), 1971
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6
Rep.
Tokyo
Kyoiku
Daigaku,
11: