CHYTRIDIALES 187 



? ACHLYOGETON SOLATIUM Comu 



Bull. Soc. Bot. France, 17: 297. 1870 



Thallus filamentous, branched, growing through several host cells; 

 sporangia of irregular size, each with a long exit tube; zoospores 

 three to twelve, encysting at the orifice of the tube, emerging from the 

 cysts. 



Parasitic in Oedogonium obsidionale, France. 



SEPTOLPIDIUM Sparrow 



Trans. Brit. Mycol. Soc, 18: 215. 1933; J. Linn. Soc. London (Bot.), 50: 428. 



1936 



(Fig. 15 C-H, p. 186) 



Thallus endobiotic, cylindrical, unbranched, holocarpic, without spe- 

 cialized vegetative system, at maturity successively divided by trans- 

 verse walls into a series of conjoined segments, each of which becomes 

 an inoperculate sporangium with a single evacuation tube through 

 which the posteriorly uniflagellate zoospores are discharged; resting 

 spore not observed. 



A monotypic genus known thus far only in diatoms. 



Septolpidium closely resembles Achlyogeton except that the zoo- 

 spores lack an encysted stage (Fig. 15 C-E, G). 



Septolpidium lineare Sparrow 1 



Trans. Brit. Mycol. Soc, 18: 215. 1933; J. Linn. Soc. London (Bot.), 50: 428, 



fig. 1. 1936 



Thallus narrowly cylindrical, smooth-walled, with slightly tapering 

 ends, 75-130 \x long by 5-12 ;jl in diameter; divided at maturity into 

 a linear series of truncated conjoined sporangia; sporangia 8-37 ij. 

 long by 5-12 [j. in diameter, each forming a single broad abruptly 

 tapering evacuation tube 3-5 [x in diameter which protrudes from the 

 host cell and through which the numerous zoospores are discharged; 

 zoospores spherical, 3-4 \i in diameter, with from one to four spherical 

 or irregularly shaped refractive granules, often forming upon emer- 

 gence a spherical motionless temporary cluster at the mouth of the 



1 See also Paterson (Mycologia, 50:93. 1958). 



