Hydrodroma CL Koch

Type species: Hydrodroma despiciens (O. F. Müller)

Diagnosis (after Cook 1974): Body not compressed, wider than high and without a median dorsal furrow; integument is papillose; dorsalia absent; lateral eyes present but not in capsules; the lenses associated with the integument and widely separated from each other; median eye absent; coxae in four groups; genital flaps well developed and bearing numerous acetabula; no pronounced sexual dimorphism; legs with swimming setae but these reduced in size and number in stream inhabiting species; capitulum with a short rostrum; claws with a clawlet; palp five­segmented; dorsodistal portion of P­4 extending far beyond the base of the fifth segment to form a scissor­like end; distomedial portion of P­2 with pectinate setae.