Phylum：Oomycota　>>　Class： Oomycetes　>>　 Order： Saprolegniales 
   
 
　BCRC Number： NO BCRC Number!  
   
　Scientific Name： Pythiopsis humphreyana
 
   
   
　Author：

Pythiopsis humphreyana Coker. Mycologia 6: 292, pl. 148. 1914.
   
 
 
 
 
　Description： Hyphae slender, sparingly branched, about 11-25 μ thick which are stoutest in the neighborhood of the asexual reproductive bodies. Sporangla varying in shape from spherical, oval or pyriform to elongate and irregular forms; dis-charging by a short or rather long papilla and usually proliferating from below in a cymose manner. Oogonia generally borne exactly like sporangia and not to be distinguished from these when young, apical and often in group by cymose branching; usually spherical with a basal neck. Oogonia 30-37.5 μ in diameter. Oospore subeccentric, 1-2 predominantly 1 in number; 27 μ in diameter. Antheria arising from immediately below the oogonium.
 
 
 
 
 
　Specimens：

Collected from soil and water samples in all seasons. (Dec. 16, 1974.Shih-lin, Taipei).
 
 
 
　Habitat： Soil and water
 
 
 
　Distribution：

Chapel Hill, N Carolina ; Taiwan
 
 
 
　References：

Coker, WC. 1923; Sparrow FK Jr. 1960.
   
   
   
　Provided：

T. S. Chiou and H. S. Chang
 
 
　Note： This oomyceteous species was widely distributed in Taiwan, has been baited by hemp seeds from paddy or arable soils more than 20 times. While this species initially described by Coker in 1914, no mature oospores were illustrated. The subsequent study by Lund (1934) indicated the oospore was eccentric, in conteast to the subeccenteic type oospore found by us in Taiwan.This species were erected by Coker (1923), but the oospore structure had not been observed. Lund (1934) described this species with eccentric oospore type, which was different from that at P. cymosa, Dick (1974) suggested that P. humphreyana might be a species of the genusSaprolegnia (or Isoachlya). The aforementioned opinions made this species become somewhat vague to identify. Recently we identified many isolated of Pythiopsis as P. humphreyana(Chiou et al 1975). Present study showed that they possessed subeccentric oospore type, large oogonia and oospores, monomorphic primary zoospore and no basal antheridial branches. Moreover, we found the germination of this oospore type. So we suggest it should be retained in the genus Pythiopsis and be a valid species, just as Coker (1923) described.Ookubo & Kobayasi (1955) erected a new species Pythiopsis papillata with dimorphic zoospores and did not mention whether the immature oogonial wall of their fungus with or withouta conspicuous mucilage layer. Based on their origin description, we think that P. papillata is closer to Pythiaceae by hyphae diameter, oospore type and antheridial branches origin. However, lacking the material, we cannot make further discussion. The following key is proposed for the separation of four species of Pythiopsis.