Orphella Hiemalis: A New and Rare Trichomycete Occurring in Winter-Emerging Stoneflies (Plecoptera, Capniidae)

Orphella hiemalis Peterson, Lichtwardt & Huss (Zygomycotina, Trichomycetes, Harpellales) from the hindgut of winter-emerging stonefly nymphs of the genus Allocapnia (Plecoptera, Capniidae) is described and illustrated. It was found in only a few nymphs from two stream sites, one in northwestern Arkansas on the Ozark Plateau, the other in eastern Oklahoma in the Ouachita Mountains. It appears to be a rare species, in contrast to some other gut fungi in Allocapnia spp. Like O. haysii from Nemouridae nymphs in Colorado Rocky Mountain streams, mature sporulating heads of O. hiemalis protrude from the host's anus, and trichospores do not detach from their generative cells in the manner typical of most other Harpellales. Rather, a 3-celled dissemination unit is formed by individual clavate generative cells breaking away from a basal cell together with a sterile, filiform terminal cell and attached allantoid trichospore.