CHYTRIDIALES 211 



Karling (1939a) suggested the suppression of the name Phlyctidium, 

 because of its earlier use by Wallroth (1833) for a genus of Ascomy- 

 cetes, and the substitution of a new name, Tylochytrium. All species 

 of Wallroth's genus have long since been transferred to other genera 

 and Phlyctidium possesses no status among the Ascomycetes. In view 

 of this, as well as of the long- and well-established use of the name for 

 certain chytridiaceous fungi, Phlyctidium should be treated as a nomen 

 conservcmdum, a course now evidently concurred in by Karling (1946d). 



KEY TO THE SPECIES OF PHLYCTIDIUM 1 



Wall of sporangium persistent at least for a short time at discharge 

 of the zoospores, of uniform thickness 

 Endobiotic part (haustorium) uniformly tubular, clavate apoph- 

 ysate or expanded distally 

 Sporangium smooth-walled 



Haustorium apophysate, sporangium spherical or ovoid 



P. apophysatum, p. 212 

 Haustorium lacking an apophysis, sporangium spherical, 

 citriform, ellipsoidal, ovoid or urceolate 

 Sporangium spherical, ovoid, or when a prominent lateral 

 papilla is formed, somewhat anatropous, with 1-3 



blunt conical discharge papillae P. later ale, p. 213 



Sporangium citriform or ovoid, broader than high, with 



two opposite discharge papillae P. irregulare, p. 214 



Sporangium spherical or ellipsoidal, somewhat urceolate 

 after discharge, 16-70 [i in diameter, haustorium a 



distally expanded peg P. megastomum, p. 214 



Sporangium urceolate, 15-17 [i in diameter, haustorium 



tubular throughout P. olla, p. 215 



Sporangium wall ornamented 



Sporangium broadly urceolate or broadly ovoid, with an 

 apical collarette of from four to eight plain prominent teeth 



P. brebissonii, p. 216 

 Sporangium spherical or slightly ovoid, wall covered with 



short sharp spines P. spinulosum, p. 216 



Endobiotic part spherical, knoblike, discoid, or very short and 

 peglike or needle-like 

 Sporangium attached laterally, appearing more or less procum- 

 bent, sessile, irregularly shaped, in general broadly pyri- 



1 Note that this key is not consistently dichotomous. See also new taxa, p. 223. 



