1) Achirus declivis Chabanaud, 1940,

Achiridae .

Plainfin Sole; Suela Simple (Fig. 3I).

New record for the Matina River basin; previous records of the species in Costa Rican freshwaters were restricted to the Tortuguero and Parismina River basins. New elevational record (7 m. a.s.l.); previous records of the species in Costa Rican freshwaters were restricted to 0– 3 m.a.s.l. Basis of the record: Three specimens were captured in the río Moín, at the Puerto Fluvial JAPDEVA, Limón (09.99745, -83.08077), at 7 m. a.s.l., on December 14, 2006, by Karina Rodríguez (UCR 2761-003).