The northern riffleshell, scientific name Epioblasma torulosa rangiana, is a subspecies of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.This subspecies is endangered.This species was formerly found widely in the Ohio River basin, but now the population is fragmented into only three viable groups. This river mussel needs gravel river beds and swift-flowing, well-oxygenated water.