Hydrocolus is a genus of beetles in the family Dytiscidae, containing the following species: \n* Hydrocolus deflatus (Fall, 1923) \n* Hydrocolus filiolus (Fall, 1923) \n* Hydrocolus heggiensis Ciegler, 2001 \n* Hydrocolus oblitoides Roughley & Larson, 2000 \n* Hydrocolus oblitus (Aubé, 1838) \n* Hydrocolus paugus (Fall, 1923) \n* Hydrocolus persimilis (Crotch, 1873) \n* Hydrocolus rubyae (Larson, 1975) \n* Hydrocolus rufiplanulus (Fall, 1923) \n* Hydrocolus rupinus Roughley & Larson, 2000 \n* Hydrocolus sahlbergi Nilsson, 2001 \n* Hydrocolus stagnalis (Gemminger & Harold, 1868)