GYMNOGEOPHAGUS EOCENICUS, N. SP. (PERCIFORMES: CICHLIDAE), an eocene Cichlid from the Lumbrera Foramtion in Argentina

MALABARBA, C; MALABARBA, L; DEL PAPA, C.

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Año: 2010 vol. 30 p. 341 - 350

0272-4634

A new cichlid referable to the extant genus Gymnogeophagus is described from the Eocene Lumbrera Formation of the Salta Group, northwestern Argentina. †Gymnogeophagus eocenicus, n. sp., presents the synapomorphies that support the genus: absence of supraneurals and a presence of a forward spine in the first dorsal pterygiophore. The existence of an early to middle Eocene–aged species presenting the synapomorphies and the appearance of a modern genus requires the acceptance of an extensive differentiation from the basal cichlid lineages. Extant Gymnogeophagus species are restricted to the La Plata drainage and a few coastal drainages of southern Brazil and Uruguay. The occurrence of an Eocene fossil in the geographical area corresponding to the present distribution of the genus suggests the patterns of distribution and endemism of the Neotropical fish fauna have a very old history in the continent. INTRODUCTION Cichlids are teleost fishes found chiefly in fresh waters. They are one of the major vertebrate families with more than 1500 species (Eschmeyer and Fong, 2008), being one of the most speciose families of percoid fishes. Due to this speciosity besides the ecological and evolutionary features, cichlids are among the most widely studied fish. Contrasting with this effervescence of the recent forms is the scarce fossil record. Even with the recent reports (Murray, 2000, 2001; Carnevale et al., 2003; Malabarba et al., 2006), the cichlid fossil record is still meager if it is compared to such diversity of the recent forms. Fossil cichlids are known from Africa, Europe, Central and South America, and the Near East. In South America, cichlids are recorded for Oligocene–Miocene of Brazil and Miocene and Eocene of Argentina (Arratia and Cione, 1996; Malabarba et al., 2006). The first cichlid records in the Argentinean sediments, †Aequidens saltensis and †Acaronia longirostrum, were reported by Bardack (1961) from the exposures in the Salta Province, northwesternArgentina. Casciotta andArratia (1993a) described Miocene cichlid fossils from northern Argentina and proposed a phylogenetic hypothesis of relationships for Recent and fossil American cichlids. The only fossil fish remains reported for the Lumbrera Formation, northwestern Argentina, were detached dental plates assigned to Lepidosiren paradoxa (Fernandez et al., 1973), until the description of the cichlid fish, †Proterocara argentina Malabarba, Zuleta, and del Papa, 2006, from this formation and from the same fossil level as the material reported here. Currently, the genus Gymnogeophagus Miranda Ribeiro, 1918, includes 10 species occurring in the southern South America drainages. Gymnogeophagus is a geophagine genus whose monophyly is supported by the absence of supraneurals and the presence of a forward spine in the first dorsal pterygiophore in the analyses of Reis and Malabarba (1988) and Casciotta and Arratia (1993a). It has been also diagnosed by the presence of *Corresponding