New Evidence for True Facultative Anaerobiosis in Two Members of the Rhipidiaceae with Notes on Occurrence Frequencies and Substratum Preferences

SUMMARY

Rhipidium sp. and Mindeniella spinospora were repeatedly obtained on fruit baits from freshwater habitats in northern California. Systematic sampling of Lake Anza near Berkeley showed Rhipidium sp. to be restricted during warm months to the poorly-oxygenated hypolimnion. Mindeniella spinospora from Trapper Slough near Stockton occurred over a dissolved-oxygen range of from near zero to greater than 6 ppm. In laboratory studies, both species were capable of growth under strict anaerobic (leuco methylene blue) conditions. Leaves and immature acorns from Quercus agrifolia were colonized by Rhipidium sp. at Lake Anza, and may represent potential natural substrata.