HETEROVESICULA-COWANI N-G, N-SP (HETEROVESICULIDAE N FAM), A MICROSPORIDIAN PARASITE OF MORMON CRICKETS, ANABRUS-SIMPLEX HALDEMAN, 1852 (ORTHOPTERA, TETTIGONIIDAE)

Heterovesicula cowani, n. g., n. sp., is a dimorphic microsporidium de scribed from the adipose tissue of the Mormon cricket, Anabrus simplex Haldeman. Proliferation of the microsporidium is by karyokinesis of u ninucleate and binucleate cells to form binucleate and tetranucleate c ells, respectively. These cells will undergo binary fission (merogony) , Ultimately, the meronts undergo karyokinesis without subsequent cyto kinesis producing spherical multinucleate plasmodia that are transitio nal to 2 types of sporogony. Transitional to disporoblastic sporogony, a fragile interfacial envelope delaminates from the plasmodium with m orphogenesis to a monfiliform plasmodium consisting of fusiform binucl eate diplokaryotic sporonts. These undergo karyokinesis to form tetran ucleate diplokaryotic sporonts that undergo cytokinesis during disinte gration of the plasmodium into isolated binucleate sporonts. Transitio nal to octosporoblastic sporogony, multinucleate plasmodia disintegrat e into short monofiliform plasmodia of diplokaryotic sporonts which th en segregate while undergoing gradual nuclear dissociation (haplosis b y nuclear dissociation). These undergo two sequences of karyokinesis a nd subsequent multiple fission to form eight uninucleate (haploid) spo roblasts in a fusiform arrangement within a persistent envelope. Binuc leate spores are ovocylindrical, about 5.4 x 1.7 mu m (flesh), with an isofilar polar filament singly coiled about 11 turns. Uninucleate spo res are ovoid to slightly pyriform, 4.0 x 1.7 mu m (fresh), with an is ofilar filament singly coiled about 9 turns. A new family, Heterovescu lidae, is proposed for the new genus.