846 AQUATIC PHYCOMYCETES 



APLANES de Bary 



Bot. Zeitung, 46: 613. 1888 

 (Fig. 66 E, p. 842) 



"Mycelium as in Achlya. Sporangia extremely scarce, often entirely 

 absent for long periods in culture, cylindric, renewed as in Saprolegnia 

 and perhaps also as in Achlya; spores at times escaping as in Achlya or 

 Saprolegnia, at times retained in the sporangium and sprouting there, 

 their behavior not well known in all species. Oogonia abundant, in 

 chains or single and terminal, barrel-shaped, spheric, or pyriform, their 

 walls very thick (more so than in other water-molds) and heavily pitted ; 

 eggs centric or subcentric, spheric or at times elliptic from pressure. 

 Antheridial branches arising from immediately below the oogonia, or 

 when the oogonia are in chains arising from the top of one oogonium 

 and attached to the next above, simple or branched; antheridia with 

 their sides attached to the oogonia" (Coker and Matthews, 1937). 



Type species : Aplanes braunii de Bary. 



Johnson (1956) has demonstrated that the best-known species, Aplan- 

 es treleaseanus, is in fact an Achlya. If, as is possible, the others belong 

 either in Achlya or Saprolegnia, the genus can be suppressed. Its validity 

 now rests on two doubtful criteria: (1) rarity of sporangia and (2) 

 germination of the zoospores in situ. 



THRAUSTOTHECA Humphrey 



Trans. Amer. Phil. Soc. (N.S.), 17: 131. 1893 

 (Fig. 65 J-K, p. 836) 



"Primary threads in greater part stout, branching. Sporangia clavate 

 to subcylindric, often irregular, proliferating from below as in Achlya; 

 spores always or in great majority encysting within the sporangium 

 when formed and later, in more or less angular form, swelling and 

 escaping by irregular rupture or disintegration of the sporangial wall, 

 not escaping at once by an apical papilla except in the Achlya-iike 

 primary sporangia of one species. Eggs eccentric, usually multiple. 

 Antheridia present" (Coker and Matthews, 1937). 



Type species: Thraustotheca claxata (de Bary) Humphrey. 



