Overview

Comprehensive Description

Biology

The collection locality is around 1135 m above sea level and the rio dos Couros in that point has moderate riparian vegetation, typically between 10 and 15 m wide, and 1.5 m deep. Although with some rapids, the water is clear, the substrate composed of stones, rocks, and some stretches with mud. A natural 10 m high waterfall named Cachoeira São Bento is located downriver and all topotypes were collected on the stretch downstream from the waterfall in a small stream draining directly into the river (about 100 m from the channel river). This stream is about 0.8 m deep and 6 m wide, transparent water with moderate vegetation covering the channel (trees and shrubs), and bottom with small stones, submerged logs and roots. No other fish species was collected with this species in the stream. The rio dos Couros has several waterfalls, some with about 100 m height (Cachoeira de São Vicente and Catarata dos Couros). Stomach contents of five specimens with fragments of allochthonous insect, fish scales, and vegetal organic matter (leaf parts) and the stomachs were not full (Ref. 84461).
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Distribution

South America: Brazil. Astyanax goyanensis is known from tributaries of the rio dos Couros, affluent of rio Tocantinzinho, and rio Paranã basin, upper rio Tocantins basin, Chapada dos Veadeiros, Goiás, Brazil (Ref. 84461).
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Upper Tocantins River basin, Brazil.
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Physical Description

Size

Max. size

9.0 cm SL (male/unsexed; (Ref. 38376))
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Diagnostic Description

This species belongs to the A. scabripinnis species complex and is distinguished from all species of this complex by the total number of pelvic-fin rays (7 vs. 8), except from A. brachypterygium Bertaco & Malabarba, A. ita Almirón, Azpelicueta & Casciotta, and A. obscurus (Hensel), Bertaco & Lucena (2010). It differs from A. brachypterygium by caudal peduncle length (14.1-18.5% SL, mean = 16.1 vs. 11.9-14.4, mean = 13.0), by the number of caudal-peduncle scales (14 vs. 16), and by the number of cusps of the premaxillary inner series and the larger dentary teeth (4-5 vs. 5-7); from A. ita by the number of branched anal-fin rays (13-16 vs. 20-24), number of humeral spots (2 vs. 1), and by the orbital diameter (20.2-33.2% HL, mean = 27.4 vs. 38.6-42.0, mean = 40.2); and from A. obscurus by the number of maxillary teeth (2-5 vs. 1), number of lateral line scales (35-37, mean = 36 vs. 37-39, mean = 38), and by the number of branched anal-fin rays (13-16, mean = 14.7 vs. 16-21, mean = 18.3). Furthermore, the lower number of the branched anal-fin rays in A. goyanensis distinguish it from its congeners of the species complex, except from A. brachypterygium, A. cremnobates Bertaco & Malabarba, A. laticeps (Cope), A. intermedius Eigenmann, A. jenynsii (Steindachner), A. jordanensis Alcaraz, Pavanelli & Bertaco, A. microschemos Bertaco & Lucena, A. totae Haluch & Abilhoa, and A. varzeae Abilhoa & Duboc. It differs from most these species by the number of humeral spot (2 vs. 1), except A. brachypterygium, A. cremnobates, and A. varzeae. From these three species it differs by the number of cups in the premaxillary and dentary teeth (5-7 vs. 3-5), and by the caudal-peduncle length (14.1-18.5% SL, mean = 16.1 vs. 11.9-14.4, mean = 13.0, 11.0-14.9, mean = 13.1, 10.5-13.9, mean = 12.4, respectively), and additionally from A. varzeae by the number of lateral line scales (35-37, mean = 36 vs. 37-42, mean = 39) (Ref. 84461).
  • Bertaco, V.A., F.R. Carvalho and F.C. Jerep 2010 Astyanax goyanensis (Miranda-Ribeiro, 1944), new combination and Astyanax courensis, new species (Ostariophysi: Characiformes): two Characidae from the upper rio Tocantins basin, Central Brazil. Neotrop. Ichthyol. 8(2):265-275. (Ref. 84461)
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Ecology

Habitat

Environment

benthopelagic; freshwater; depth range ? - 2 m (Ref. 84461)
  • Bertaco, V.A., F.R. Carvalho and F.C. Jerep 2010 Astyanax goyanensis (Miranda-Ribeiro, 1944), new combination and Astyanax courensis, new species (Ostariophysi: Characiformes): two Characidae from the upper rio Tocantins basin, Central Brazil. Neotrop. Ichthyol. 8(2):265-275. (Ref. 84461)
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Conservation

Threats

Not Evaluated
  • IUCN 2006 2006 IUCN red list of threatened species. www.iucnredlist.org. Downloaded July 2006.
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