Astyanax gymnodontus Pavanelli &amp; Oliveira 2009, new combination
Creators: name: Pavanelli, Carla Simone
name: Oliveira, Carlos Alexandre Miranda
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Characiformes
Characidae
Astyanax
Astyanax gymnodontus

description: <i>Astyanax gymnodontus</i> (Eigenmann, 1911), new combination <b>Figs. 4-5</b> <i>Psalidodon gymnodontus</i> Eigenmann, 1911: 166 (original description; type-locality: Porto União, rio Iguaçu; illustration; holotype FMNH 54574, ex CM 3204). - Eigenmann &amp; Myers, 1929: 455 (reproduction of the original description; illustration). - Fowler, 1948: 162 (checklist of Brazilian freshwater fishes). - Géry, 1977: 578 (comparison with <i>Henochilus wheatlandi</i>; referred to the Cheirodontinae; partial illustration). - Severi &amp; Cordeiro, 1994: 41 (translation of the original description; rio Iguaçu; illustration). - Garavello <i>et al</i>., 1997: 74 (redescription; Segredo Reservoir). - Malabarba, 1998: 230 (type-species of <i>Psalidodon</i>). - Lima <i>et al</i>., 2003: 154 (checklist of South and Central American fishes). <i>Astyanax</i> sp. F. -Sampaio, 1988: 70 (description; rio Iguaçu; illustration). -Severi &amp; Cordeiro, 1994: 29 (description; rio Iguaçu; illustration). -Garavello <i>et al</i>., 1997: 73 (description; Segredo Reservoir). -Haluch &amp; Abilhoa, 2005: 386 (comparison with <i>Astyanax totae</i>). -Abilhoa &amp; Duboc, 2007: 49 (comparison with <i>Astyanax varzeae</i>). <i>Psalidodon</i> sp. -Garavello <i>et al</i>., 1997: 74 (description; Segredo Reservoir). <b>Diagnosis.</b> <i>Astyanax gymnodontus</i> can be distinguished from all other congeners at the rio Iguaçu basin except for <i>A</i>. <i>varzeae</i> by the combination of the following characters: thirdinfraorbital margin separated from preopercle by broad skin area as wide as 1/5 to 1/3 of its depth (<i>vs</i>. adjacent or separated by a narrower skin area); teeth with a cutting edge forming a straight line or a convex arc in frontal view (<i>vs</i>. concave arc); premaxillary teeth with five (rarely seven) cusps, with the median being the largest and the other cusps abruptly decreasing in size to the sides (<i>vs</i>. commonly seven, rarely four, five or nine cusps, gradually decreasing laterally); transversally located black humeral blotch (<i>vs</i>. longitudinally located); 21 to 24 anal-fin rays and 37 to 41 lateral-line scales (<i>vs</i>. 18 to 22 and 34 to 38, respectively, in <i>A</i>. <i>totae</i>); and no hooks on pelvic or anal fins. <i>Astyanax varzeae</i> is the congener most similar to <i>A</i>. <i>gymnodontus</i> in the basin, but the latter can be diagnosed by having a deeper body, 2.4 to 3 times in the SL (<i>vs</i>. 3 or 3.5 in <i>A</i>. <i>varzeae</i>), and a longer snout, 3.2 to 4.7 times in the HL (<i>vs</i>. 4.3 to 6.1). <b>Description.</b> Body elongated and laterally compressed, body deeper at dorsal-fin origin. Predorsal and prepelvic regions of body rounded transversely. Dorsal profile of snout convex, straight or slightly concave from eye to supraoccipital process. Dorsal profile of body gently convex from supraoccipital process to dorsal-fin end, straight or slightly convex from this point to adipose-fin base, straight or slightly concave from this point to caudal fin. Ventral profile of body convex, between anterior tip of jaw and pelvic-fin origin, straight from this point to anal-fin origin. Dorsal-fin origin slightly forward or at vertical through pelvic-fin origin, its distal margin straight. Pectoral-fin origin at vertical through posterior edge of opercle, its margin rounded, when adpressed, reaching or almost reaching pelvic-fin origin. Pelvic-fin origin at about vertical through dorsal-fin origin, its margin slightly convex, when adpressed not reaching anal-fin origin. Anal-fin origin just behind vertical through end of dorsal-fin base, its distal margin slightly concave. Caudal fin with symmetric lobes, or inferior slightly longer, and scales only at base. Dorsal-fin rays ii or iii,8 to 10 (mean = 9.4); pectoral-fin rays i,11 to 14 (mean = 12.5); pelvic-fin rays i,7 or 8 (mean = 7.5); anal-fin rays iii,19 to 22 (mean = 20.8). Lateral line complete, with 37 to 41 perforated scales, generally 39 or 40; 6 to 8 rows of scales above lateral line, generally 7, and 5 or 6 below. Third-infraorbital margin separated from preopercle by a broad skin area, as wide as 1/5 to 1/3 of its depth. Dentary larger teeth 5 to 7, with three cusps, in anterior row, and smaller 4 to 7, generally 5 or 6 in posterior row. Premaxillary teeth 4 to 7, generally 5 or 6, with five cusps, in inner row, 1 to 4 with three cusps regular or irregularly arranged in outer row, when present. Outer row commonly not bilaterally symmetric. Maxillary teeth 1 to 4 with three cusps. All teeth with largest median cusp, abruptly decreasing in size up to smallest more laterally placed. Cutting edge of teeth with cusps in a straight line or forming a very wide convex arc in frontal view. Lips absent or, when present, ranging from poorly developed to completely covering premaxillary and dentary teeth. Polymorphism in teeth and lips development is shown in Fig. 5.
description: Published as part of <i>Pavanelli, Carla Simone &amp; Oliveira, Carlos Alexandre Miranda, 2009, A redescription of Astyanax gymnodontus (Eigenmann, 1911), new combination, a polymorphic characid fish from the rio Iguaçu basin, Brazil, pp. 569-578 in Neotropical Ichthyology 7 (4)</i> on pages 573-574, DOI: 10.1590/S1679-62252009000400003, http://zenodo.org/record/5420950