Zoological Studies

Vol. 51 No. 6, 2012

Morphology and DNA Barcoding Reveal a New Species of Eagle Ray  from the Southwestern Atlantic: Myliobatis ridens sp. nov. (Chondrichthyes: Myliobatiformes: Myliobatidae)

Natalia L. Ruocco1,*, Luis O. Lucifora2,3,4, Juan M. Díaz de Astarloa2,5, Ezequiel Mabragaña2,5, and Sergio M. Delpiani2,5

1CInstituto Nacional de Investigación y Desarrollo Pesquero, Paseo Victoria Ocampo s/n, B7602HSA, Mar del Plata, Buenos Aires, Argentina
2Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
3Instituto de Biología Subtropical – Iguazú, CONICET, Universidad Nacional de Misiones, Casilla de Correo 9, N3370AVQ, Puerto Iguazú, Misiones, Argentina
4Centro de Investigaciones del Bosque Atlántico, Casilla de Correo 9, N3370AVQ, Puerto Iguazú, Misiones, Argentina
5Laboratorio de Biotaxonomía Morfológica y Molecular de Peces, Instituto de Investigaciones Marinas y Costeras (IIMyC)-CONICET, FCEyN, Universidad Nacional de Mar del Plata, Funes 3350, B7602AYL, Mar del Plata, Buenos Aires, Argentina

Natalia L. Ruocco, Luis O. Lucifora, Juan M. Díaz de Astarloa, Ezequiel Mabragaña, and Sergio M. Delpiani (2012) Two species of Myliobatis, the southern eagle ray M. goodei Garman and the bullnose eagle ray M. freminvillii Le Sueur, have long been recognized to occur in coastal Argentinean waters.  Several unusual specimens belonging to the family Myliobatidae were recently collected off Buenos Aires Province, Argentina.  These specimens clearly belong to the genus Myliobatis, since they have a broad disk with long sharply pointed pectoral fins, a projecting snout, a very long and thin tail, and a smaller dorsal fin set farther back on the tail, well beyond the pelvic fins.  However, the specimens were distinct from all sympatric congeners in several characters, and they are described here as a new species.  Myliobatis ridens sp. nov. is distinguished from M. goodei in having a relatively shorter snout, a wider interorbital space, a wider mouth, and different shapes of the ventral and dorsal marginal cartilages of the claspers than the latter; and from M. freminvillii by having smaller eyes, a smaller dorsal fin, a plain dorsal coloration, and a different shape of the dorsal marginal cartilage of the claspers.  In order to test this morphological differentiation, cytochrome c oxidase subunit I (COI) sequence data were obtained from the new species and compared to those of its congeners.  Analysis of COI sequences showed a congeneric sequence divergence of > 6%, supporting species differentiation.  Therefore combining both traditional taxonomy and DNA barcoding, a new eagle ray species, M. ridens sp. nov., from the Southwest Atlantic Ocean was discovered.

Key words: Elasmobranchii, Myliobatis, Cytochrome c oxidase subunit I gene, South America, Argentina.

*Correspondence: Tel: 54-223-4862586.  E-mail:nruocco@inidep.edu.ar