OSTEOLOGICAL ANALYSIS OF THE KILLIFISH GENUS CYNOLEBIAS (CYPRINODONTIFORMES, RIVULIDAE)

Relationships among the species of the annual fish Cynolebias are uncl ear. An analysis of the variation and utility of osteological characte rs for phylogenetic analysis was done using cleared and double-stained specimens representing 21 species of Cynolebias. This analysis showed that some of the characters previously used to diagnose this genus an d some of the species are polymorphic. Osteologically, Cynolebias can be diagnosed by the following synapomorphies: (1) triangular-shaped pa rietal, (2) vomer positioned ventral to the parasphenoid, (3) long ven tral process of the dentary, (4) teeth on fourth ceratobranchial, and (5) teeth on first epibranchial. In addition, characters that help def ine some of the currently recognized species complexes were identified . Species in the ''antenori complex'' share at least five synapomorphi es, such as ossified medial radials of dorsal and anal fins, four pect oral radials, ventral process of the maxillae enlarged, mesopterygoid long relative to the autopalatine, and proportion of cartilage in the basihyal. The ''bellottii complex'' is characterized by having a reduc e basihyal and a deep urohyal, whereas species in the ''elongatus comp lex'' possess a caudal fin supported by four vertebrae and have unique modifications of jaw bones. The following osteological features are u seful as diagnostic characters at the specific level: (1) Two vertebra e supporting the caudal fin (C. nigripinnis); (2) cartilaginous pelvic bones (C. notatus); (3) short third postcleithrum and broad lateral p rocess of the sphenotic (C, wolterstorffi); (4) thick third postcleith rum (C. gymnoventris); (5) crest on the parietal and reduced in the up per portion of the lacrimal (C. whitei); (6) anteriorly curved lacrima l(C. cheradophilus); (7) second dermosphenotic (C. bellottii); and (8) expansion of the ventral tip of the ma;maxillae and long basyhial (C. constanciae). (C) 1998 Wiley-Liss, Inc.