For the past several decades, it has been thought that Colostethus inguinalis (Cope, 1868) (type species of Prostherapis Cope, 1868) is distributed in the Chocó region of western Colombia and throughout much of Panama. This study shows that C. inguinalis is a Colombian endemic known only from the lowlands of the Chocó and Magdalena Valley—an unusual distribution pattern among dendrobatids but one shared with a several other anuran species typically known from the Chocó region. Colostethus cacerensis Rivero, 2000 “1995” is argued to be a junior synonym of C. inguinalis. The available name for the tetrodotoxin-possessing species found in Panama is C. panamensis (Dunn, 1933), which is redescribed. The first record of C. panamensis in Colombia is also reported. Colostethus inguinalis and C. panamensis differ from each other in ventral coloration of adult males and adult females, flank coloration, head coloration, relative tympanum size, and mean adult female snout-vent length. Colostethus latinasus (Cope 1863) (type species of Colostethus Cope, 1866) is most similar to C. panamensis but differs in a variety of characters, including ventral coloration and toe webbing. The exact provenance of the neotype of C. latinasus is unclear, but material that agrees closely with it was collected in Panama in the Serranía de Pirre; specimens previously reported as C. latinasus from Cerro Malí in the Serranía del Darién are not conspecific with that taxon and represent an undescribed species to be named elsewhere. It is doubtful that the Colombian holotype of C. latinasus (lost for over 80 years) was conspecific with the Panamanian neotype, and specimens that agree with the neotype have yet to be discovered in Colombia. Limited data on tadpole transport provide additional evidence for the validity of several species of Colostethus that occur in western Colombia and Central America: Nurse frogs of C. panamensis and C. pratti (Boulenger, 1899) appear to be exclusively female, of C. talamancae (Cope, 1875) both sexes have been reported, and of C. flotator (Dunn, 1931), C. nubicola (Dunn, 1924), and Colostethus sp. from Cerro Malí they appear to be exclusively male. The phylogenetic significance of these observations awaits further analysis.