LAGENIDIALES 1003 



well -developed mycelial thallus of this species strongly resembles that 

 of an Aphragmium type of Pythium. Whether a fertilization tube is 

 formed, as seems probable, is not clear from de Wildeman's description. 



Lagenidium marchalianum de Wildeman 



Ann. Soc. Beige Micro. (Mem.), 21 : 10, pi. 1, figs. 1-9. 1897 



(Fig. 8 IB, p. 1002) 



Thallus predominantly narrowly cylindrical, 2.2-9 [i in diameter, 

 with occasional irregularly expanded parts up to 13 u, in diameter, 

 especially near the point of infection, sparingly branched, ramifying 

 through many cells of the host, strongly constricted and only 1 \i in 

 diameter when passing through the cross walls, cyst and infection tube 

 persistent; sporangia delimited by narrow cross walls, generally 

 unaccompanied by constrictions, 30-90 [jl long by 5-9 [jl in diameter, 

 each with a single lateral cylindrical discharge tube 1.5-3 u. in diameter 

 and up to 30 [i long extending for varying distances extramatrically; 

 zoospores few (often only four), grape-seed-like, with a shallow furrow, 

 a vacuole, and a few refractive globules in the clear plasma, delimited 

 within the sporangium and completing their maturation at the orifice 

 of the discharge tube, the vesicle quickly disappearing at discharge; 

 plants monoecious or dioecious, female gametangium monandrous, 

 rarely parthenogenetic, intercalary, rarely terminal, formed from an 

 expanded segment, up to 20 [j. in diameter; resting spore lying loosely 

 in the gametangium, spherical, 8-18 [jl in diameter, contents with a large 

 eccentric globule, wall smooth, thick (3 u.), germination not observed; 

 male gametangium a somewhat expanded segment either adjacent to the 

 female gametangium or arising as a short lateral subtending branch of 

 the adjacent cell or as a short lateral branch of another thallus, forming 

 a fertilization tube. 



Parasitic in vegetative cells of Oedogonium sp., de Wildeman (Joe. cit.), 

 Belgium; Oedogonium sp., Couch (1935b: 384, figs. 39-40), Sparrow 

 (1943: 672), United States. 



This species, like the following ones, closely resembles an Aphragmium 

 type of Pythium, not only in its predominantly cylindrical hypha-like 

 thallus, but in its strongly polyphagous habit and sex organs. The 



