Review of the genus Isca (Ephemeroptera, Leptophlebiidae) from China with a new species and a new species record

Previously, only one Isca species (Isca purpurea Gillies, 1951) was recorded in China. In this review, three Isca species are presented and photographed. Among them, I. acutata sp. nov. is a new species with an acute male penal apex, a uniform brown abdomen of the imago, and a bilamellate gill VII of the nymph.

Another species, I. fascia, previously reported from Vietnam, is found in China for the first time. The nymphs of I. fascia exhibit a banded body and a convex apex of the penes. The structure of the third species I. purpurea, shown graphically, has separated penes and a paler nymphal body than the other two species.

The diverse morphology of the penes, wings, venation, and gills show that Isca has diverse species and evolutionary directions, suggesting that the previous subgeneric classification may not adequately represent some species. Biologically, their nymphs were observed living in tiny pits on substrate surfaces, where their ventral gills may facilitate respiration while they hide.