Two new species of Characidium, C. tatama and C. dule, are described from the biogeographic Chocó region in western Colombia. Both new species are supported by both morphological and molecular data. C. tatama from the San Juan River in the Pacific and C. dule from the Atrato River in the Caribbean portion of Colombia are both distributed in the upper and lower portions of these basins. An extensive comparison with other trans- and cis-Andean species of Characidium was made, in addition to species delimitation, using COI sequences by distinct methods (GMYC, ABGD, bPTP).
Keywords: Atrato River; DNA; San Juan River; South American darters; scaless isthmus.
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