Saprolegnia variabilis sp. nov. is described from litter (floating twigs, leaves, and roots) in a artificial polluted channel, near a petroleum refinery, in Buenos Aires Province, Argentina. The species is illustrated and compared with other species of the genus. It differs from S. australis in having mature subcentric oospores; the oogonia and the oospores are larger and more variable in shape and size, and the number of oospores is greater. The oogonial stalks are also variable in length and the zoosporangia are very much longer.Instituto de Botánica "Dr. Carlos Spegazzini

Elíades, Lorena Alejandra

Steciow, Mónica Mirta

New Zealand Journal of Botany

English

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679New Zealand Journal of Botany, 2002. Vol. 40: 679-6850028-825X/02/4004—0679 $7.00 © The Royal Society of New Zealand 2002
A new species of Saprolegnia (Saprolegniales, Straminipila), from a 
polluted Argentine channel
MONICA MIRTA STECIOW
LORENA ALEJANDRA ELÍADES
Instituto de Botánica Spegazzini
53 N° 477
(1900) La Plata
Buenos Aires, Argentina
Very little is known about Argentinian water 
moulds since the literature contains few references, 
principally about polluted habitats of Buenos Aires 
Province (Steciow 1988, 1993a,b, 1997). Previous 
contributions have been made (Steciow et al. 
2001a,b) about zoosporic organisms isolated from 
the above habitat.
Abstract Saprolegnia variabilis sp. nov. is described 
from litter (floating twigs, leaves, and roots) in a 
artificial polluted channel, near a petroleum refinery, 
in Buenos Aires Province, Argentina. The species is 
illustrated and compared with other species of the 
genus. It differs from 5. australis in having mature 
subcentric oospores; the oogonia and the oospores 
are larger and more variable in shape and size, and 
the number of oospores is greater. The oogonial 
stalks are also variable in length and the 
zoosporangia are very much longer.
Keywords Straminipila; Saprolegnia; Argentina; 
systematics
INTRODUCTION
During a survey of zoosporic organisms occurring 
in hydrocarbon-polluted water and organic matter 
floating in streams and channels, near the YPF- 
Repsol Petroleum Refinery, Partido de Ensenada, 
Buenos Aires Province (Argentina), we found a 
species which belongs to the genus Saprolegnia but 
with distinctive features, thereby separating it from 
other species in the genus; it is here named S. 
variabilis Steciow et Elfades. It belongs to the 
Kingdom Straminipila, Phylum Heterokonta, Class 
Peronosporomycetes (Alexopoulos et al. 1996; Dick 
2001).
B0/055; Published 28 November 2002
Received 5 November 2001 ; accepted 3 July 2002
MATERIAL AND METHODS
The methods described by Coker (1923), Sparrow 
(1960), and Seymour (1970) were used. Samples of 
brown decaying twigs and leaves and wood of the 
local dominant vegetation, collected from an 
artificial channel, were brought to the laboratory in 
separate sterile polyethylene bags. This channel is 
located at Partido de Ensenada, Buenos Aires 
Province, Aigentina. It receives the effluents of the 
refinery and of coke production, with principally 
aliphatic (3.642 pg L’) and aromatic (4.34 pg I-') 
hydrocarbons found in water samples (established by 
gas chromatography).
The samples were placed in water culture in 
sterilised Petri dishes containing several halves of 
hemp seeds (Cannabis saliva), for incubation at 
room temperature (15-20°C). After growth of the 
fungus on the seeds a single hypha or spore was 
isolated and transferred to cornmeal agar medium. 
After 3—4 days, a block of agar from the edge of each 
colony was cut off and placed in sterilised Petri 
dishes containing distilled water, and halves of hemp 
seeds were added in order to obtain new colonies. 
Measurements and observations were made on those 
colonies. Some colonies were incubated at 5,10, and 
25°C to observe the possible effect of temperature 
on the variation of sexual structures. Mean diameters 
of fungus colonies, diameters of oogonia, numbers 
of oospores per oogonium, and diameters of 
oospores were calculated from 50 counts of each of 
three replicates. The total percentage of type of 
antheridial branches was calculated from all these 
replicates.
680 New Zealand Journal of Botany, 2002, Vol. 40
'■
Fig. 1-6 Saprolegnia variabihs Fig. 1 Detail of zoosporangium renewal by internal proliferation, with development 
of a new one inside. Fig. 2 Zoosporangium with a long papilla with zoospores inside. Fig. 3 Filiform zoosporangium 
with zoospores. Fig. 4—6 Gemmae functioning as zoosporangia with some papillae for discharge. Scale bars: 
Fig. 1-3 = 100 pm; Fig. 4, 6 = 50 pm; Fig. 5 = 10 pm.
Fig. 7-14 Saprolegnia variabilis. Fig. 7 Mature pyriform oogonium with detail of subcentric oospores of different >■ 
size. Fig. 8 Obovate oogonium. Fig. 9 Spherical, pyriform, and fusiform oogonia. Fig. 10 Catenulate oogonia. Fig. 11 
Oval oogonium. Fig. 12-13 Intercalary and doliform oogonia with numerous oospores. Fig. 14 Clavate oogonium. 
Scale bars « 50 pm.
Steciow & Elíades—Saprolegitia variabilis sp. nov 681
682 New Zealand Journal of Botany, 2002, Vol. 40
Fig, 15-20 Saprolegnia variabilis. Fig. 15-16 Navicukte oogonia. Fig. 17-18 Pyriform and irregular oogonia.
Fig. 19 Filiform oogonium. Fig. 20 Long oogonial stalk tapering towards the end. Scale bars = 50 pm.
Fig, 21-28 Saprolegnia variabilis. Fig. 21 Pyriform oogonium with a short lateral projection. Fig. 22-26 Oogonia 
with spherical and ellipsoid subcentric oospores, variable in number and size. Fig. 27 Diclinous antheridial branches. 
Fig. 28 Oogonium with monoclinous antheridial branch. Scale bars; Fig. 21—26 = 50 pm; Fig. 27-28 = 100 pm.
Steciow & Elíades—Saproìegnia variabiìis sp. nov 683
684 New Zealand Journal of Botany, 2002, Vol. 40
The type specimen is deposited in the 
mycological herbarium of Spegazzini Institute (LPS) 
and its culture collection.
SPECIES DESCRIPTION
Saprolegnia variabilis Steciow et Eliades, sp. nov.
Fig. 1-28
Mycelium densum, cultura in seminibus Cannabis 
sativae 1.5-3 cm diam. Hyphae ramosa, pleraque 
25-56 pm late diam. ad basim. Sporangia in culturis 
juvenilibus, filiformia, fusiformia vel clavata, 
(127-) 137-407 (485) pm larga et 20-49 pm lata, 
renovata per proliferarionem internam. Ejecto 
sporarum pro genus typica, zoospori incystatis 
globosi 10-12 pm. Gemmae frequentis. Oogonia 
copiosa, pyriformia, sphaerica, cylindrica, obovate, 
naviculate vel apiculata, (39)51-92(153) pm diam. 
Paries oogonia laevis, ramulus lateralibus 
provenientia, 200-1000 pm. Oospori (1)3-18(60) 
per oogonium, subcentrici, (9)15-30(56) pm diam. 
Ramulus an th eri diales, ramosus, diclina (84% ± 9), 
monoclina (9% ± 7) et androgina (7% ± 3).
Mycelium extensive, denser near substratum, 2- 
week-old hemp seed colony, 1.5-3 cm diam.; 
principal hyphae stout, sparingly branched, 25- 
56 pm diam. at the base. Gemmae abundant, 
spherical, pyriform or irregular, single or often 
catenulate, functioning as zoosporangia with papilla 
for discharge. Zoosporangia filiform, fusiform, 
clavate or irregular; (127)137—407(485) x 20- 
49 pm; short or long, often with one or two papillae, 
usually terminal, renewal by internal proliferation. 
Zoospore discharge saprolegnoid. Encysted spores 
globose, 10-12 pm diam. Oogonia very abundant, 
terminal or lateral, often intercalary; variable in 
shape; pyriform, spherical, obovate, cylindrical, or 
often naviculate or with short lateral projections 
when terminal, or sometimes doliform or filiform
when intercalary; (39-)51-92(153) pm. Oogonial 
wall smooth; pitted or pitted only under point of 
attachment of antheridial cell. Oogonial stalks 
usually slender, frequently short to very long, 
tapering toward the end; straight or frequently bent; 
25-650 pm long, sometimes branched and helicoidal 
in old cultures. Oospheres maturing. Oospores sub­
centric, type I, filling or not filling the oogonium; 
spherical or ellipsoid; (1)3-18(60) in number; 
variable in size, (9)15-30(56) pm diam. 
Antheridia present, or very rarely absent. 
Antheridial branches slender, principally diclin­
ous (84% ± 9), occasionally monoclinous (9% ± 7), 
rarely androgynous (7% ± 3), branched. Anther­
idial cells simple or branched; attached by 
projections or laterally appressed. Fertilisation tube 
not observed.
holotypuS: Argentina, Buenos Aires Province, 
Ensenada, polluted artificial channel, on floating 
litter; April 2001, leg. M. Steciow, LPS N° 45649; 
culture collection N° 697.
ETYMOLOGY; referring to the variability in oogonial 
shape, oospore shape, oospore size, and length of 
oogonial stalks of this species.
DISCUSSION
Saprolegnia variabilis is closely related to S. 
australis Elliott (Elliott 1968; Seymour 1970). Both 
species have smooth oogonia, principally diclinous 
and also monoclinous and androgynous antheridial 
branches, and subcentric oospores. However, .S'. 
australis has immature subcentric oospores (type I 
or II), and the mycelial hyphae are more slender 
(30 pm diam. at the base).
In S. variabilis the oogonial stalk is very variable 
in length, slender, and tapering toward the end (up 
to 650 pm, 4 times the diameter of the oogonia), 
whereas in the original description for S. australis, 
the author failed to document the length of the
Table 1 Means and ranges of morphological measurements of Saprolegnia variabilis grown at 3 temperatures 
for 20 days.
Temp. °C
Colony 
diam. (cm)
Oogonia 
diam, (pm)
Oospores 
diam. (pm)
Oospores per
oogonium
Length of 
oogonial stalk
5 1.5-4.0 (40)51-77(87) (10)15-25(41) 3-15(60) (25)51-102(600)
10 2.0-4.0 (39)53-92(111) (9)15-30(44) (1)3-18(21) (51)121-300(650)
25 2.0-3.5 (40)51-81(153) (10)15-30(56) (1)3-17(25) (25)76-127(420)
Overall mean
±SD 2.5±0.4 67.1 ±6.0 25.4±4.6 9.2±2.7 174 ±8.8
Steciow & Eh'ades—Saprolegnia variabilis sp. nov 685
subtending hyphae (“two to many times the diameter 
of the oogonia in length”). Examination of the type 
slide has confirmed that this species is distinct in this 
respect.
In 5. variabilis, the zoosporangia are longer (up 
to 485 pm), 10 times larger than in 5. australis. They 
are cylindrical, filiform, fusifoim, clavate or irregular 
whereas in .S’, australis they are filiform or clavate. 
Both species have saprolegnoid internal 
proliferation. The oospores are subcentric, spherical 
and ellipsoid, type I, and (1)3-18(60) per oogonium 
and are of variable and lai ger size, (9) 15-30(56) pm, 
in S. variabilis, whereas the oospores are immature, 
type I or II, and the number and size of oospores are 
smaller, 6-12(30) and 22-24(27), respectively, in S. 
australis.
In the original description of S. australis, the 
oogonia showed variation in shape, pyriform to 
obovate, when the water culture was kept at 20 or 
25°C. In S. variabilis the oogonia also change shape 
at those temperatures; they are principally pyriform 
or spherical, doliform or filiform when intercalary, 
and larger in size at 25°C. The same increase in the 
size of the oospores appears with higher 
temperatures; however, the great number of oospores 
was developed at 5 °C. Measurements of 5. variabilis 
colonies, oogonia diameters, oospore diameters, 
oospores per oogonium, and length of oogonial 
stalks were made at three different temperatures 
(Table 1). We were unable to make the same 
measurements on S. australis for comparison 
because the type culture was no longer available (S. 
Lorraine pers. comm.).
Saprolegnia longicaulis from other freshwater 
environments in Argentina (Steciow 2001) is 
characterised by having a longer oogonial stalk (up 
to 1300 pm long) and subcentric oospores of type I 
but fewer in number (up to 26 oospores per 
oogonium), but it differs from the new species in 
having only diclinous and monoclinous antheridial 
branches, and smaller oospores (upto 34 pm diam.) 
which are constant in shape and size inside the 
oogonium.The zoosporangia are longer, up to 
700 pm.
ACKNOWLEDGMENTS
The author wish to thank Universidad National de La 
Plata and CON1CET for the financial support of these 
studies, and E. McKenzie for the loan of the type slide of 
S. australis, PDD 25944 from Western Springs, 
Auckland, New Zealand.
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A new species of Saprolegnia (Saprolegniales, Straminipila), from a polluted Argentine channel

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A new species of Saprolegnia (Saprolegniales, Straminipila), from a polluted Argentine channel

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