Observations on Certain Species of Aphanomyces

Abstract

While searching for Phycomycetous fungi in the submerged exuviae of aquatic insects during the summer of 1940, several interesting species of the genus Aphanomyces were encountered. The identity of two of these proved puzzling and a search of the existing literature on the subject indicated that neither of them corresponded completely with any published description. Since these forms appeared to be fairly common in the vicinity of Ann Arbor, Michigan, further study of them seemed desirable. At the same time, Dr. F. K. Sparrow, Jr., kindly made available preserved material of a number of other species of Aphanomyces, collected from time to time by him. A study of these forms revealed a great deal of variation among them. Since the preserved material was in excellent condition, it appeared worthwhile to undertake a comparative morphological study of as many of the aquatic species of this genus as possible in the hope of clarifying to some extent certain obscure aspects of these fungi, in particular, specific limits. The genus Aphanonmyces was erected by de Bary in 1860 and since that time approximately 20 more or less distinct species have been described by various workers from many parts of the world. It is interesting to note that the species are for the most part distributed in the temperate zones, and few records are extant from any tropical countries. Species have been described from many types of substrate, including other aquatic fungi, algae, the exuviae of aquatic insects, insect cadavers in water, aquatic animals, and higher plants. The members of this genus fall into two main categories de-