Late-stage larvae of the family Microdesmidae (Teleostei, Gobioidei) from Belize, with notes on systematics and biogeography in the western Atlantic

Late-stage larvae of five species of wormfishes, family Microdesmidae, are described from Belize in the western Caribbean. They are distinguished by f in-ray and vertebral counts and chromatophore patterns. Cerdale floridana i s widely distributed in the Caribbean, southern Florida, and Bermuda. Micro desmus bahianus, originally known from southern Brazil and Martinique, was found to extend north and west as far as Panama and Belize. Meristic charac ters inM. bahianus vary geographically, with the population from Belize the most distinct. Microdesmus carri occurs only in the western Caribbean and the Gulf of Mexico. Microdesmus longipinnis occurs throughout the tropical and subtropical western Atlantic and shows a more complex pattern of variat ion; three more-or-less distinct populations were found. Finally, two speci mens were collected at Belize that cannot be identified with a known specie s, although they show some resemblances to Microdesmus lanceolatus. Three o f the species were reared through transformation to juveniles. Microdesmid adults are cryptic in habits and difficult to collect. Larvae, on the other hand, are easily collected in plankton nets. Larvae are thus more readily available and provide much valuable information on systematics and biogeogr aphy that would not be available from study of adults alone.