Saprolegnia - The iLumina Digital Library

(see this species) also produce oogonia with imperfectly developed oospores
(Willoughby, 1971a). While the oospores of S. australis are subcentric, those of S. diclina
are predominantly centric. Both species have pitted, generally obpyriform oogonia that,
in S. australis are primarily terminal, but are predominantly lateral in S. diclina. These
two species are thus separable on few characters, and those that may be used show
degrees of variation that encompass features of both. Further study of additional
isolates may show the two to be variants of one species.
Padgett (1978b) demonstrated that Saprolegnia australis is capable of actively
invading mesohaline estuarine waters (see Chapter 3). The fungus also has been found
associated with fish (Pickering and Willoughby, 1977, on Perca fluviatilis; Hatai, Egusa,
and Nomura, 1977, on fingerlings of rainbow trout); such a habitat further relates
Elliott’s species to S. diclina (which includes S. parasitica sensu Kanouse).
The chief experimental work with Saprolegnia australis has been that by R. F.
Elliott (1968). She propagated the species under a variety of culture conditions noting
that oospore number and colony and oogonium sizes could be modified. On the other
hand, oospore structure and the origin and degree of branching of the antheridial
filaments were not changed by manipulating the environmental parameters during
incubation. At 25 o C colonies of S. australis produced larger oogonia containing more
oospores than did isolates grown at 20 o C. Larger oogonia, and ones with fewer
oospores, developed on mycelium propagated in larger culture vessels rather than in
smaller ones.
CONFIRMED RECORDS: -- CANADA: Maestres (1977:144, 145, figs. 21-23);
Nolan and Maestres (1978:892, figs. 1, 2). JAPAN: Hatai, Egusa, and Nomura (1977:204,
figs. 6-9). NEW ZEALAND: R. F. Elliott (loc. cit.). UNITED STATES: Padgett
(1976:1260, figs. 1, 2); Shipman (1977: fig. 10).
RECORDED COLLECTIONS: -- BRITISH ISLES: Pickering et al. (1979); Pickering
and Willoughby (1977). CANADA: Maestres and Nolan (1978). UNITED STATES:
Klich (1980); Padgett (1978a); Shipman (1979).
SPECIMENS EXAMINED: -- CANADA (1), NEW ZEALAND (1), R. F. Elliott,
preserved specimens. NORWAY (1), TWJ. UNITED STATES (1), DEP.
Saprolegnia hypogyna (Pringsheim) de Bary
Bot. Zeitung (Berlin) 41:56. 1883
(Figure 94 A-D)
Saprolegnia ferax var. hypogyna Pringsheim, Jahrb. Wiss. Bot. 9:196, pl. 18, figs. 9, 10.
1873-74.
Saprolegnia hypogyna var. I Maurizio, Flora 79:126, pl. 4, figs. 5-12. 1894.
Saprolegnia hypogyna var. II. Maurizio, ibid., p. 128, pl. 4, figs. 13-16. 1894.
Saprolegnia hypogyna var. III. Maurizio, ibid., p. 129, pl. 4, figs. 17-20a. 1894.
Saprolegnia hypogyna var. IV. Maurizio, ibid., p. 131, pl. 4, figs. 21-23. 1894.
Saprolegnia hypogyna var. V. Maurizio, ibid., p. 132, pl. 4, figs. 24-27. 1894.
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