There are currently four recognized species in this genus:[1] The genus Otothyris is distributed along the Atlantic coast of Brazil between Barra do Ribeira, Guaíba River Basin of Rio Grande do Sul State in the south to the Jequitinhonha River Basin of Bahia State in the north.

The species are apparently restricted to the lowland sections of these river systems near the coast and have not been collected further to the west in higher elevation or headwater streams.

The head and margin of the snout have enlarged odontodes arranged in dorsal and lateral series.

[2] Within Otothyris, O. lophophanes, O. juquiae, and O. rostrata have larger and more extensive odontode crests, more pronounced odontode ridges, larger swimbladder capsule, and larger pterotic fenestrae, in comparison with O. travassosi, which has smaller, shorter odontode crests and less pronounced ridges, a relatively small swimbladder capsule, and smaller pterotic fenestrae.

[2] Otothyris species also differ in tooth counts, lateral line and abdominal plates, and morphometrics.