Astyanax xiru

description

Description. Morphometric data summarized in Table 1. Body compressed and elongate, with greatest body depth anterior to dorsal-fin origin. Dorsal profile of head straight or slightly convex from posterior nostril to tip of supraoccipital spine. Dorsal body profile convex from tip of supraoccipital spine to base of last dorsal-fin ray; straight from latter point to adipose fin origin. Ventral profile of body slightly convex from vertical through posterior nostril to pelvic-fin origin, nearly straight to anal-fin origin, and posterodorsally slanted along anal-fin base. Caudal peduncle elongate, nearly straight to slightly concave in the dorsal and ventral margins. Snout rounded from margin of upper lip to vertical through anterior nostrils. Mouth terminal, jaws isognathous. Maxilla extending posteriorly to vertical through anterior margin of orbit. Two tooth rows in premaxilla; outer row with 4 (8) *, 5 (5) or distinct combinations considering left / right sides, 4 / 5; 6 / 4 or 6 / 5 pentacuspid teeth, central cusp longer; inner row with five teeth, gradually decreasing in length from the first to fourth, last distinctly smaller, with seven cusps; except the first tooth with asymme

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

diagnosis

Diagnosis. Astyanax xiru is distinguished from its congeners from the rio Uruguay basin and laguna dos Patos and rio Tramandaí systems by the presence of two humeral spots and the shape of the first humeral spot: upper portion horizontally elongate and lower portion vertically narrow (vs. one spot in A. eigenmanniorum, A. sp. aff. fasciatus, A. jacuhiensis, and A. laticeps and ovale shape in last two species); by the presence of one maxillary tooth (vs. 2 - 5 in A. henseli and 3 - 4 in A. paris), by the maxillary tooth tri- to pentacuspid (vs. heptacuspid in A. ojiara and A. dissensus new species), by the number of branched anal-fin rays (18 - 22 vs. 25 - 30 in A. saguazu and A. stenohalinus, 23 - 29 in A. aramburui, 18 or less in A. brachypterygium and A. cremnobates), by the body depth (32.3 - 37.5 % vs. 38.3 - 46.0 % of SL in A. procerus new species), by the presence of a very few small hooks on anal and pelvic-fin of males (vs. absence in A. obscurus). Most similar to A. procerus in color pattern, differing by the pelvic-fin length (13.6 - 17.1 % vs. 16.1 - 18.7 % of SL), dorsal-fin length (21.1 - 25.4 % vs. 24.1 - 28.7 % of SL), males with bony hooks on the anal and pelvic fin

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

discussion

Comments. Astyanax xiru has some characters that define Astyanax scabripinnis species complex sensu Bertaco & Lucena (2006). However, we decided not considering it as belonging to that complex by the presence of a relatively pointed snout, head less massive and higher body in the vertical through the dorsal-fin origin. This not precludes that the species is indeed related to the Astyanax scabripinnis species complex. The following lots were cited as A. obscurus by Bertaco & Lucena (2010). All from laguna dos Patos system, Rio Grande do Sul State, Brazil: MCP 15396, 13, 65.5 - 87.9 mm SL, tributary of arroio Feitoria, Sapiranga, ca. 29 º 35 ’ S 51 º 06 ’ W. MCP 20017, 2, 42.1 - 76.7 mm SL; MCP 20040, 13, 25.9 - 44.5 mm SL; MCP 21331, 4, 75.9 - 77.9 mm SL, arroio Feitoria, Sapiranga, ca. 29 º 34 ’ S 51 º 00 ’ W.

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

distribution

Distribution. Astyanax xiru is known from the rio Jacuí drainage, laguna dos Patos system, and from the upper rio Uruguay drainage, Rio Grande do Sul, and Santa Catarina States (Fig. 9). Additional specimens listed did not differ from the population of the laguna dos Patos system but only specimens this system were included as paratypes in order to maintain type series from a single basin.

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