Sommerstorffia spinosa Arnaudov 1923

Sommerstorffia spinosa Arnaudow, Flora 116: 109. 1923
Mycelium fine, not well developed, parasitic in the body of the rotifer Monostyla, and also extending out into the water; hyphae 4-6 /x thick, inside the rotifer up to 8 m) tips of many branches in the form of a spike; zoosporangia long, of the same size as ordinary hyphae; zoospores in a single row, encysting at the mouth of the sporangium, then emerging as biciliate zoospores; empty cysts 10m (encysted zoospores 7.2 ju, according to Sparrow); oogonia spiny, borne terminally on short branches; eggs smooth, one to an oogonium, about 22 ^ thick; germination unknown; antheridia lacking. (Compiled from the original description.)
Type locality: Sofia, Bulgaria.
Habitat: Parasitic in Monostyla.
Distribution: Massachusetts and New York; also in Bulgaria.