Wednesday, September 27, 2017

[Ichthyology • 2017] Astyanax taurorum • A New Species (Characiformes: Characidae) from dos Touros River, Pelotas River Drainage, An Upland southern Brazilian River

Astyanax taurorum 
 de Lucena, Zaluski & de Lucena, 2017 

A new species of Astyanax belonging to the Astyanax scabripinnis complex is described from dos Touros River, tributary of the Pelotas River, Uruguay River basin. Astyanax taurorum sp. nov. is distinguished from other species of the Astyanax scabripinnis species complex by having two humeral spots, the first vertically elongated; teeth of inner row of premaxilla with three to five cusps; 2–3 (modes 2 or 3) maxillary teeth; 20–23 (mode 22) branched anal-fin rays; 13–15 (mode 14) gill rakers on lower branch of the first branchial arch; 20–23 (mode 21) total gill rakers in first branchial arch; 33–36 (mode 35) perforated lateral line scales. Astyanax taurorum sp. nov. is similar to Astyanax paris; nevertheless, it can be readily distinguished from it by having a smaller head depth (73.6-83.1% vs. 86.4–95.6%) and smaller interorbital width (24.1–28.0% vs. 30.8–32.8%). In addition, it differs from A. paris by the presence a posttemporal hook-shaped posterodorsal margin.

Key words: Taxonomy, Rio Grande do Sul, Uruguay River, distribution

Figure 1.  Astyanax taurorum sp. nov., MCP 49468, 80,7 mm SL, holotype, tributary of dos Touros River, Rio Grande do Sul, Brazil. 

Figures 5–6.  (5) Distribution of Astyanax taurorum sp. nov., white circle = type-locality. The symbol represents more than one locality; (6) stream tributary of dos Touros River, type locality of Astyanax taurorum sp. nov. 

Astyanax taurorum sp. nov.

Etymology: The specific name taurorum, is derived from the Latin masculine noun taurus (second declension, meaning bull) inflected in the plural and genitive case. Therefore taurorum means “of the bulls” in reference to “rio dos Touros“ (= Portuguese, which means “river of the bulls”) the type locality.

Distribution and habitat: Astyanax taurorum sp. nov. is known from the dos Touros River drainage, tributary of Pelotas River, which in turn is a tributary of Uruguay River (Fig. 5). The Pelotas River drainage is located in the region named “Campos de Altitude do Planalto das Araucárias (= Araucaria Plateau in Bertaco et al. 2016)” or “Campos de Cima da Serra”, which has a high level of endemism of fishes (Malabarba et al. 2009, Bertaco et al. 2016: 430) and other groups of animals (for example: sponges, Ribeiro et. al. 2009; crustaceans, Bond-Buckup et al. 2009). The dos Touros River tributary, type locality of Astyanax taurorum sp. nov., has a low to medium flow, transparent waters with stones and rocks on the bottom and moderate emergent marginal vegetation (Fig. 6). Four characid species were caught along with Astyanax taurorum sp. nov.: Bryconamericus patriciae Silva, 2004, B. iheringi Boulenger, 1887, Cheirodon interruptus Jenyns, 1842, and Oligosarcus brevioris Menezes, 1987.

 Carlos Alberto S. de Lucena, Amanda Bungi Zaluski and Zilda Margarete Seixas de Lucena. 2017. Astyanax taurorum A New Species from dos Touros River, Pelotas River Drainage, An Upland southern Brazilian River (Characiformes: Characidae). 
 Zoologia. 34; 1-8.  DOI: 10.3897/zoologia.34.e20174

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