Biogeographic Studies on Trichomycete Gut Fungi in Winter Stonefly Nymphs of the Genus Allocapnia

Lichtwardt, Robert; Huss, Martin; Williams, Marvin

ABSTRACT: Winter stoneflies of the genus Allocapnia (Plecoptera, Capniidae) have low vagility, and first evolved in the Appalachian system from where they slowly dispersed and speciated times during the Pleistocene. Five described genera and species of Harpellales (Trichomycetes) the aquatic nymphs of Allocapnia. Two of these, Genistelloides hibernus and Simuliomyces found widely distributed in 53 stream sites in nine states that include the western and tribution limits of Allocapnia spp. This suggests that the fungi had already evolved in Allocapnia before major radiation pulses of the stoneflies during the Pleistocene. Two other fungi, magnus and Capniomyces stellatus, were more limited in their distribution and might subsequent to early Allocapnia dispersals. One species, Orphella hiemalis, may be endemic Plateau and Ouachita Mountains. The presence of different extant species of Genistelloides in the stonefly faunas of North America and Europe indicates that species of those two must have existed prior to the final separation of the two continents during the Lower Eocene. were extracted and electrophoresed from 25 axenic cultures of G. hibernus obtained from When grouped by geographic region, the greatest coefficient of similarity among fungal notypes was between the Ozarkian isolates and those from northeastern Texas. However, between central Tennessee and Kansas were greater than they were between eastern Alabama. This apparent disparity might be explained biogeographically by a southwestward dispersal into Alabama of G. hibernus-infested Allocapnia populations originally located Cumberland Plateau and the mountains to the east, and a separate westward dispersal of ulations of fungus-infested stoneflies that were situated to the west of the Cumberland isozyme data also suggest that G. hibernus may have moved with its hosts from northern into the Ozark Plateau.