Four new species of Smittium (Zygompcota, Trichomycetes, Harpellales),
S. caudatum, S. commune, S. acutum, and S. kansense, that live in the
hindguts of stream Chironomidae (midge) larvae collected in Kansas an
d Oklahoma are described. One or more axenic cultures were obtained fr
om all species but S. kansense. Each of the cultured species has disti
nctive isozyme patterns, though 12 isolates of S. commune were split i
nto two isozyme groups. Problems in identification of Smittium spp. ba
sed solely on axenic cultures of the fungus are discussed.