María de las Mercedes Azpelicueta

Redescription of the Eocene Catfish Bachmannia chubutensis (Teleostei: Bachmanniidae) of Southern South America

ABSTRACT The Siluriformes constitutes an important monophyletic ostariophysan group of mainly freshwater fishes that occurs in almost all continents. They are extremely abundant and diverse in South America, where the oldest otophysans and siluriforms occur. We restudied two putative catfish species from the early Eocene lacustrine Tufolitas Laguna del Hunco of northwestern Patagonia, Argentina, concluding that Arius argentinus Dolgopol, 1941, is a junior synonym of Bachmannia chubutensis Dolgopol, 1941. Phylogenetic analyses were performed to show the relationships of B. chubutensis, which appears as the sister group of Diplomystes. Bachmannia chubutensis is one of the most primitive catfishes known and we based on it a new family. The family is clearly diagnosed by the presence of a anterior ventrolateral expansion of cleithrum, short maxilla with two rows of teeth, double-headed autopalatine, accessory tooth plates, very huge teeth, supraoccipital process long and acute, first and fifth vertebrae not joined to complex vertebra, neural arch of fifth and sixth vertebrae very well developed, enlarged supraneural 5, suture between ceratohyal and epihyal without interdigitations, suture between contralateral cleithra and coracoids without interdigitations, six hypurals. Individuals of B. chubutensis inhabited lakes and were preserved into fine-grained, laminated fall-out and reworked pyroclastic debris inside a caldera.

A Miocene Nematogenys (Teleostei: Siluriformes: Nematogenyidae) from south-central Chile

ABSTRACT A new species of fossil catfish, †Nematogenys cuivi (Siluriformes: Nematogenyidae) is described from the Miocene, continental fluviolacustrine deposits of the upper Cura–Mallin Formation (37–39°S), Chile. †Nematogenys cuivi is the first fossil record of the monogeneric family Nematogenyidae, which is considered the plesiomorphic sister group of the large loricarioid clade. The new species differs from the extant N. inermis in having a combination of characters: cleithrum with some weak interdigitations in the anterolateral margin, rectangular Weberian capsules wider than long, and shorter distance between the coronoid process and distal tip of the lower jaw. †Nematogenys cuivi was found together with teeth of Serrasalminae, an association that is presently unknown. It is suggested that †N. cuivi occurred in lowlands before the uplift of the Cordillera de los Andes. If it is correct, the differentiation of the genus occurred before the major uplift of the Andes.

The first fossil species of Salminus, a conspicuous South American freshwater predatory fish (Teleostei, Characiformes), found in the Miocene of Argentina

ABSTRACT The first fossil specimen of the characiform genus Salminus is described here. The material, a threedimensionally articulated head, is very well preserved and allowed us to identify a new species. We could study both outer and inner bones. The specimen was found in the locality Toma Vieja, northeast of the city of Paraná, central eastern Argentina. The bearing horizon is the so-called ‘Conglomerado osífero,’ which is putatively included in the lowermost beds of the fluvial Ituzaingó Formation. The ‘Conglomerado osífero’ is early Tortonian (early late Miocene) in age. Recent species of Salminus are top-ranking pelagic predatory fishes in temperate to tropical lowland freshwaters of South America. The aquatic vertebrate fauna occurring in the bearing bed shows a similar composition to several northern South American units such as the Urumaco Formation (Venezuela, late Miocene) and La Venta Formation (Colombia, middle Miocene).

A new species of Curimata (Characiformes, Curimatidae) from Paraná system, in Resistencia, Argentine

A new curimatid fish, Curimata gnaca, from two localities, both in the neighborhoods of Resistencia, Chaco Province, Argentine, is described. The species is distinguished from other curimatids by the position of the mouth, a low number of perforated scales in lateral line, scales with straight margin on sides of body and long pectoral fins. The new species is placed in the genus Curimata until the problems within it will be solved.