INTO ANABLEPID DIVERSIFICATION: TWO NEW LATE MIOCENE TAXA (TELEOSTEI: CYPRINODONTIFORMES) FROM NORTHWESTERN ARGENTINA

MIRANDE, J. M.; AGUILERA, G.; SFERCO, E.

Puerto Madryn

Congreso; Reunión de Comunicaciones de la Asociación Paleóntologica Argentina; 2018

Cenpat - APA

At present, the family Anablepidae is composed of three genera: Jenynsia Günther, Anableps Linnaeus and Oxyzygonectes Fowler, which live in brackish and freshwater habitats from Mexico to southern South America. In northern and central Argentina, several species of onesided livebearers (Jenynsia) are important components of freshwater environments. The family is particularly interesting as Jenynsia and Anableps are viviparous fish with sexual dimorphism, mainly exhibited by the modification of the male anal-fin into a gonopodium. Anablepid fossil record includes a premaxilla of Jenynsia sp. from the Pleistocene and two new fossil species described for the Middle Miocene Río Salí Formation of Argentina: Tucmanableps cionei, and Sachajenynsia pacha Sferco, Herbst, Aguilera and Mirande. We present here two new fossil anablepids from theLate Miocene San José Formation of Catamarca and Tucumán provinces that are different from all other known species of the family. One of them represents a new genus and species showing an incipient gonopodium formed by all anal-fin rays.In the performed phylogenetic analysis, and regarding the position of its dorsal-fin, this taxon is recovered as basal to all remaining anablepids with a well-differentiated gonopodium. The other taxon represents the first fossil species of Jenynsia and exhibits a gonopodium formed by anal-fin rays 3, 5-7. Because of the inclination of proximal male anal-fin radials and the segmentation present in the sixth ray of the fin, it is recovered within the subgenus Jenynsia in our cladistic hypothesis. These new results suggest the diversity of anablepids was greater in the past.