Three new species of Astyanax from drainages of southern Brazil (Characiformes: Characidae)

Abstract

Three new species of Astyanax are described from southern Brazil: A. dissensus and A. xiru from the laguna dos Patos system and rio Uruguay basin, the first species also occurring in the rio Tramandaí system, and A. procerus from the laguna dos Patos system. Astyanax procerus and A. xiru possess outer row premaxillary teeth pentacuspid and inner row heptacuspid, maxillary with one tri- to pentacuspid teeth, 18-23 branched anal-fin rays, and two humeral spots. Astyanax procerus has the largest body depth (38.3-46.0% of SL), while A. xiru has the lowest body depth (32.5-37.5% of SL) among the three species. The characters combination can distinguish these species from its congeners. Astyanax dissensus distinguish from Astyanax species by the presence of one developed heptacuspid teeth on maxillary, 22-28 branched anal-fin rays, 35-39 perforated scales along the lateral line, two humeral spots, conspicuous lateral band continuous on middle caudal rays, 6-7 scale row between dorsal-fin origin and lateral line, and head length 22.7-27.3% of SL. All three species has the predorsal region of the body scaled. An identification key to the species of Astyanax species from the rio Uruguay basin, and laguna dos Patos and rio Tramandaí systems is provided.

Ichthyofauna of the hydrographic basin of the Chasqueiro Stream (Mirim Lagoon system, southern Brazil): generating subsidies for conservation and management

“…The collected fish were stored in plastic bags, labeled, and fixed in 10% formalin, and were then taken to the laboratory where they were transferred to 70% alcohol. Specimens were identified with the help of specialized literature (Reis & Malabarba 1988, Buckup & Reis 1997, Rodriguez & Reis 2008, Caravalho & Reis 2009, Bertaco & Lucena 2010, Carvalho et al 2012, Lucena et al 2013, Malabarba et al 2013, and specialists were consulted when needed for species confirmation. The list of species was formulated according to Wiley & Johnson (2010) and Malabarba et al (2013).…”

A new species of Astyanax Baird & Girard (Ostariophysi: Characidae) from the rio Taquari-Antas basin, southern Brazil

“…Astyanax bagual is herein assigned to Astyanax according to the definition of the genus given by Eigenmann (1921Eigenmann ( , 1927, which is still often used (Lucena et al, 2013a(Lucena et al, , 2013bIngenito & Duboc, 2014). The new species shares two of three synapomorphies that define node 200 of Mirande (2010), which included the Astyanax clade and Astyanax paris clade as well as the Aphyocharacinae, Aphyoditeinae, Cheirodontinae, Gymnocharacinae, Stevardiinae, and Bryconamericus scleroparius clade: fourth infraorbital approximately square or more developed longitudinally than dorsoventrally, and coronomeckelian situated mainly dorsal to Meckel cartilage.…”

“…The upper rio Taquari-Antas basin is recognized as an area of endemism for hosting a large number of endemic taxa (Carvalho & Reis, 2011;Becker et al, 2013;Ferrer & Malabarba, 2013;Lucena et al, 2013aLucena et al, , 2013b. According to Becker et al (2013), species with restricted ranges are potentially more susceptible to environmental impacts and extinction, and they should be considered as targets for assessments in conservation planning and environmental licensing.…”

“…Sex of adult specimens was recognized by macroscopic examination of their gonads and/or by the presence or absence of bony hooks in fin rays. The diagnosis presented here follows the procedures described by Lucena et al (2013b: 538 Bertaco & Lucena (2006, 2010 and Lucena et al (2013aLucena et al ( , 2013b.…”

“…Presently, there are 18 recognized species of Astyanax in the main hydrographic basins of Rio Grande do Sul State (rio Uruguay, laguna dos Patos, and rio Tramandaí) (Lucena et al, 2013a(Lucena et al, , 2013bBertaco, 2014). During a revisionary study of Astyanax from these basins, an endemic new species was recognized from tributaries of the rio Taquari-Antas, rio Jacuí drainage, laguna dos Patos system, which is described herein.…”