Diplobatis

Abstract: We examined the morphological characters and internal anatomical features of the electric ray genus Diplobatis (Torpediniformes, Narcinidae) in order to determine the taxonomic status of the various forms. All specimens from the northern coast of South America (Colombia to Brazil) were found to be very variable in most morphological characteristics but to be identical in skeletal structure. Based on overlapping proportional measurements and a lack of distinguishing characters (both internal and external), D. altenai Boeseman 1963 is synonymized with D. pictus Palmer 1950, and the placement of D. guamachensis ~lartin 1957 in synonymy with D. pictus by Bigelow and Schroeder (1962) is verified. Three subspecies are recognized within D. pictus: D. pictus l}ictus Palmer, D. pictus guamachensis Martin, and D. pictus colombiensis new subspecies. D. ommata (Jordan and Gilbert 1890), from the Pacific coasts of Mexico and Central America, is found to be identical to D. pictus in skeletal anatomy and similar to its congener in most proportional measurements. D. ommata is distinguished from D. pictus by its dorsal color pattern and differing clasper morphology. The genus and species of Diplobatis are redefined, and the three subspecies are described. Finally, the four genera of Narcinidae (Benthobatis, Diplobatis, Discopyge, and Narcine) are compared and found to be very conservative anatomically. A phylogenetic analysis based on synapomorphic character states shows Discopyge and Narcine to be the sister group to the other narcinids. RESUMEN: Examinamos las caracteristicas morfol6gicas y anatomia interna de la raya electrica del genero Diplobatis (Torpediniformes, Narcinidae) a fin de determinar el estatus taxon6mico de sus varias formas. Todos los especimenes de la costa norte de Sudamerica (desde Colombia hasta Brasil) variaron notablemente en la mayoria de sus caracteristicas morfol6gicas pero fueron identicos en estmctura esqueletica. De acuerdo a coincidencia en medidas proporcionales y a la falta de caracteres internos y extemos distinguibles, la especie D. altenai Boeseman 1963 se considera sin6nima aD. pictlls Palmer 1950. Asimismo, se veri fica la sinonimia de D. guamachensis Martin 1957 con D. pictus por Bigelow y Schroeder (1962). Se reconocen tres subespecies pertenecientes a D. pictus: D. pictus pictus Palmer, D. pictus guamachensis Martin yD. pictus colombiensis nueva subespecie. D.ommata, proveniente de las costas pacificas de Mexico y America Central, se considera identica aD. pictus en cuanto a anatomia del esqueleto y similar a su congenere en la mayorfa de sus medidas proporcionales. D. ommata se distingue por su patr6n dorsal de color y diferente morfol6gia de los ganchos copulatorios ("clasper"). Se redefine el genero y las especies de Diplobatis y se descrihe tres suhespecies. Finalmente, los cuatro generos de Narcinidae (Benthobatis, Diplobatis, Discopyge y Narcine) se comparan y se concluye que son anat6micamente mtly conservativos. EI amilisis filogenetico basado en caracteres sinapom6rficos demuestra que Discopyge y Narcine son grupos hermanos de los otros