Saprolegnia - The iLumina Digital Library
Saprolegnia - The iLumina Digital Library
Saprolegnia - The iLumina Digital Library
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23. Predominantly 2-3 oospores per oogonium;<br />
oospores generally 16-22 µm in diameter;<br />
pitted, at least at the region of attachment<br />
of antheridial cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S. luxurians (p. 646)<br />
<strong>Saprolegnia</strong> truncata Seymour<br />
Mycotaxon 92:1-10, figs. 41-51. 2005<br />
(Figure 91 C-M)<br />
Monoecious. Mycelium limited, dense; hyphae moderately stout (16-) 24–26<br />
(-35) µm in diameter, sparingly branched. Sporangia rare; naviculate or cylindrical,<br />
appearing very early or proliferating from immature oogonia after prolonged culture,<br />
then subspherical with a long, cylindrical exit tube; straight or slightly curved; renewal<br />
not observed; not persistent; averaging 120 x 28 µm; discharge papilla with thickened,<br />
flaring wall; basal portion often thick-walled. Spores dimorphic; discharge and<br />
behavior saprolegnoid; cysts 9-13 µm in diameter. Gemmae, when present, naviculate<br />
or spherical; terminal or intercalary; single; smooth. Oogonia abundant; terminal or<br />
lateral, rarely intercalary; single; spherical, occasionally ovoid; (18-) 34-38 (-45) µm in<br />
diameter, exclusive of papillae. Oogonial wall unpitted; ornamented with prominent,<br />
truncate projections: (9-) 14-16 (-29) µm long, occasionally intermixed with papillae.<br />
Oogonial stalks up to 8 times the diameter of oogonium, in length; straight, slender,<br />
unbranched. Oospores subcentric; spherical or ovoid, occasionally ellipsoidal; 1, rarely<br />
2 per oogonium, and plerotic or aplerotic; (36-) 29-33 (-42) µm in diameter; germination<br />
unknown. Antheridial branches rare; androgynous, usually arising immediately below<br />
the oogonium to which attached, single; not persistent. Antheridial cells simple;<br />
laterally appressed; persisting; fertilization tubes unknown.<br />
Holotype: Fig. 91 (C-M); Accession Nr. MS 242, Randall <strong>Library</strong> Special<br />
Collection, Univ. of North Carolina at Wilmington (USA), isolated from roadside forest<br />
soil, highway BR 174 to Boa Vista, 60 km from Manaus, Brazil 5 March 1978.<br />
Among the species of <strong>Saprolegnia</strong> with ornamented oogonia, S. truncata is<br />
distinctive by reason of its stout, prominent wall protrusions. <strong>The</strong>se generally are<br />
truncate (Fig. 91 G, H, L) but on some oogonia (Fig. 91 J) a few rounded papillae also<br />
may be produced.<br />
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