Description of Issia

The genus is probably polymorphic and diplokaryotic; merogony is unknown; disporoblastic, diplokaryotic sporonts give rise to two binucleate sporoblasts and spores; the two spores are glued together in a more or less permanent way, by material occuring in between them; spores are arranged in the couple with the long spore axes parallel; spores, 3.54 x 2 µm are oval to slightly pyriform; extruded polar filaments are isofilar of considerable length (200-300 µm); type species I. trichopterae (Weiser, 1946) Weiser, 1977 in the fat body of larvae of Plectrocnemia geniculata (Trichoptera, Plectrocnemidae).