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Saprolegnia delica Coker, Saprolegniaceae, p. 30, p1s. 4 (lower photo), 5, 6, 14 (lower photo). 1923. Saprolegnia parasitica sensu Coker, ibid., p. 57, pl. 18. 1923. Isoachlya parasitica (Coker) Nagai, J. Fac. Agric. Hokkaido Imp. Univ. 32:12, pl. 2, figs. 27-34. 1931. Saprolegnia parasitica Coker emend. Kanouse, Mycologia 24:447, p1s. 12, 13. 1932. Saprolegnia pseudocrustosa Lund, Kongel. Danske Vidensk. Selsk. Naturvidensk. Math. Afh. 9 6:9, fig. 2. 1934. Isoachlya anisospora var. indica Saksena and Bhargava, Curr. Sci. 13:79, figs. 1, 2. 1944. Cladolegnia stagnalis (Tiesenhausen) Johannes, Feddes Repert. Spec. Nov. Regni Veg., p. 212. 1955. Saprolegnia diclina var. numerosa Cejp, Oomycetes I, Flora ČSR, Ser. B, Part 2, p. 219. 1959. Saprolegnia diclina var. minima Cejp, ibid., p. 219, fig. 78h. 1959. Saprolegnia crustosa var. similis Cejp, ibid., p. 224. 1959. Saprolegnia crustosa var. punctulata Cejp, ibid., p. 225. 1959. Saprolegnia shikotsuensis Hatai, Egusa, and Awakura, Fish Pathol. 12:105, figs. 1-9. 1977. Monoecious. Mycelium sparingly to moderately branched. Sporangia cylindrical, clavate, fusiform, or irregular; straight or slightly curved, sometimes faintly sigmoid; renewed internally, or in cymose or basipetalous succession; 75-1050 x 20-80 µm. Spores dimorphic; discharge and behavior saprolegnoid, or very rarely aplanoid; encysted spores 9-12 µm in diameter. Gemmae, when present, pyriform, obpyriform, cylindrical, clavate, or irregular; terminal or intercalary, single or catenulate. Oogonia sparse to moderately abundant, and often appearing in culture only after prolonged incubation; terminal, lateral, or intercalary, single or catenulate; spherical, subspherical, obpyriform, napiform, or slightly irregular, dolioform or subspherical when intercalary; spherical ones (30-) 50-70 (-130) µm in diameter, subspherical or obpyriform ones 54-146 x 18-72 µm. Oogonial wall unpitted, pitted, or with pits only under the region of attachment of antheridial cells; pits sometimes inconspicuous; smooth. Oogonial stalks ( 1 / 3 -) 1-1 1 / 2 (-3) times the diameter of the oogonium, in length; stout, straight or curved; unbranched or once-branched. Oospores centric or subcentric, both types occurring in some oogonia; spherical, (1-) 8-16 (>100) per oogonium, and may or may not fill it; (12-) 18-26 (-44) µm in diameter; at germination forming a slender, irregular germ tube terminating in a small, cylindrical or clavate sporangium. Antheridial branches diclinous, rarely monoclinous or androgynous; slender, irregular, sparingly branched or unbranched; frequently, occasionally, or infrequently wrapping about or closely applied to the oogonium; persisting or deliquescing. Antheridial cells simple, very rarely compound; tubular or clavate, often irregular, sometimes branched or lobed; persisting or deliquescing; laterally appressed, very rarely apically attached to the oogonial wall; fertilization tubes, when present, persisting or deliquescing. 628
The predominance of diclinous antheridial branches (Fig. 99 A-C) -- these are often very abundant and may indeed enwrap oogonia partially or fully (Fig. 99 G) -- sets Saprolegnia diclina apart readily from all species in the genus except S. australis (see discussion, this species). In the general configuration of its oogonia, S. diclina certainly resembles S. ferax, but in the latter, the antheridial branches (when present) are predominantly monoclinous or androgynous, and are not as prominently displayed. Like S. ferax, S. diclina produces both centric and subcentric oospores, and the two types may occur in the same oogonia. Milanez (1968:100) observed subcentric oospores in some oogonia of his specimens of Humphrey’s species. A characteristic of Saprolegnia diclina not amply emphasized in previous treatments of the species is its proclivity toward latent development of the oogonia. Gross cultures hastily examined -- and as hastily discarded as nonsexual specimens -- may indeed account for the apparent absence of this very common and widely distributed species in accounts of surveys and floristic studies. Nonsexual cultures of Saprolegnia should be kept for at least 4-5 weeks, and preferably incubated at 10-18 o C (Coker, 1923; Kanouse, 1932; O’Bier, 1960; Willoughby, 1971a). It was Humphrey (1893) who first recognized that de Bary’s Saprolegnia dioica was a distinct species but one with a preempted name. Pringsheim (1858) had used the epithet dioica for a watermold parasitized by a chytridiaceous fungus. The name dioica also appears as a new name in a publication by Schröter and Schneider (1870) but without description or illustrations (nomen nudum). Humphrey renamed de Bary’s species diclina in reference to the preponderance of diclinous antheridial branches. A thorough analysis and circumscription of Saprolegnia diclina appears in Seymour’s (1970:45-46) monograph and the justification for the taxonomic changes he proposed is adequate and need not be repeated here. Additionally, Seymour (1970:47) commented on the similarities between S. diclina and S. parasitica (as Kanouse had defined this taxon). He emphasized that these two species shared four rather prominent characteristics, and suggested that the relationship between S. diclina and S. parasitica was not fully understood. Evidence accumulated since Seymour’s monograph -- notably in accounts by Neish (1976, 1977) and Willoughby (1971a, 1978) and our own study of specimens -- convinces us that S. parasitica (sensu Kanouse, not Coker) no longer can be retained as a species separate from S. diclina. Neish (1976, 1977) divided 20 isolates of Saprolegnia (from fish) into four categories based on sporangium and oogonium production at 10 o , 14 o , and 21 o C. Isolates in one category produced oogonia consistently, and were assignable, he concluded, to the S. diclina-S. parasitica complex. Included in a second group (his category D) were those isolates that were sporadic in their production of the sexual apparatus, but oogonia could be induced by incubating the cultures at 10 o C for four months. Neish emphasized that these isolates in category D closely resembled saprolegnians recovered from English salmonids by Willoughby (1968b, 1969, 1971a). Further, Neish commented that the majority of his isolates could not be identified precisely. He found that values for the DNA base composition (buoyant density 629
Page 1 and 2: CHAPTER 38 SAPROLEGNIA Nees von Ese
Page 3 and 4: Asterophorae (ornamented oogonia),
Page 5 and 6: very infrequently diclinous . . . .
Page 7 and 8: Essentially two types of sporangia
Page 9 and 10: Kauffman (1915); V. D. Matthews (19
Page 11 and 12: CONFIRMED RECORD: -- BRITISH ISLES:
Page 13 and 14: Saprolegnia intermedia Maurizio, Ja
Page 15 and 16: Saprolegnia irregularis is recogniz
Page 17 and 18: DENMARK: A. Lund (1978). ICELAND: T
Page 19 and 20: evert to oogonium production. Howev
Page 21 and 22: Rose (1932:25, pl. 1, figs. 6-9); S
Page 23 and 24: oogonial shape and position. She di
Page 25 and 26: (1947:27, 29, fig. 8); Dayal and Th
Page 27 and 28: SEPCIMENS EXAMINED: -- ENGLAND (1),
Page 29: Moreau (loc. cit.). GERMANY: de Bar
Page 33 and 34: us best to identify any nonoogonial
Page 35 and 36: CANADA: Chong (1973); Dick (1970, 1
Page 37 and 38: CONFIRMED RECORDS: -- AFRICA: El-Hi
Page 39 and 40: and proposed that they be called ec
Page 41 and 42: Saprolegniaceae, p. 56, pl. 17. 192
Page 43 and 44: The choice of Nagai’s (loc. cit.)
Page 45 and 46: oogonium, and filling it or not; (1
Page 47 and 48: Among the species of Saprolegnia wi
Page 49 and 50: Isoachlya luxurians Bhargava and Sr
Page 51 and 52: The sporangium discharge mechanism
Page 53 and 54: Milanez (1966:112); C. E. Miller (1
Page 55 and 56: some unidentifiable saprolegnian. R
Page 57 and 58: Saprolegnia invaderis Davis and Laz
Page 59 and 60: Although both Humphrey (1893) and C
Page 61 and 62: to accommodate Cornu’s species. T

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