214 AQUATIC PHYCOMYCETES 



There is strong likelihood that Phlyctidium laterale is confined to 

 Ulothrix or at least to members of the Ulotrichales. Sparrow's (1932b: 

 274) doubtful report of it on zygospores of Spirogyra is probably ref- 

 erable to another fungus. 



Phlyctidium irregulare de Wildeman 



Ann. Soc. Beige Micro. (Mem.), 14: 21. 1890 



Rhizophydium irregulare (de Wild.) Fischer, Rabenhorst. Kryptogamen-Fl., 

 1 (4): 105. 1892. 



Sporangium citriform or ovoid, 1 1-14.5 u. broad by 8-12 u. high, 

 the longer axis parallel with that of the host cell, with two opposite 

 lateral papillae (sometimes only one), 3.2-3.8 [jl broad by 1.2-1.5 u. 

 high, wall thin or somewhat thickened, smooth, colorless, resting on 

 a short 1.2-1.5 u, thick stalk, or sessile; haustorium a continuation of 

 the sporangial stalk, tubular, unbranched, 2.7-4.0 \x in diameter; zoo- 

 spores spherical, 3.5 \x in diameter, with an eccentric, colorless globule 

 and an 8 \i long flagellum, escaping upon the dissolution of the tip 

 of one (always?) of the discharge papillae; resting spore not known 

 with certainty. 



Parasitic on small diatoms, de Wildeman {he. cit.) t Belgium; Hantz- 

 chia amphioxys, Scherffel (1925b: 24, pi. 2, fig. 51), Hungary; Gom- 

 phonema constrictum, Friedmann (1952:192, fig. 2 o-r), Austria. 



Friedmann (loc. cit.) has made the most complete study of this species 

 and has seen the hitherto unobserved endobiotic part and zoospore 

 discharge. He points out that the smooth-walled, subspherical resting 

 spore (14-15 [j. in diameter by 12 [x high) with branched rhizoidal system, 

 that was associated by Scherffel with the fungus, probably belongs to 

 a species of Rhizophydium or of Chytriomyces. On the basis of his 

 determination of the nature of the haustorium, he replaces the species 

 in Phlyctidium. 



Phlyctidium mfgastomum Sparrow 



Aquatic Phycomycetes, p. 148. 1943 



Sporangium sessile, spherical or ellipsoidal, becoming somewhat 

 urceolate after discharge. 16.3-70 \x in diameter, with a broad apical 



