Astyanax xiru, Lucena, Castro & Bertaco, 2013

Casciotta, Jorge, Almirón, Adriana, Říčanová, Štěpánka, Dragová, Klára, Piálek, Lubomir & Říčan, Oldřich, 2016, First record of Astyanax xiru Lucena, Castro & Bertaco, 2013 (Characiformes: Characidae) from the río Uruguay basin of Argentina., Ichthyological Contributions of PecesCriollos 42, pp. 1-4 : 2

Astyanax xiru ( fig. 1 ). Morphometric characters are given in Table 1.

The specimens analyzed herein present most of the characters proposed by Lucena et al. (2013) in the original description of Astyanax xiru : two humeral spots (the first humeral spot vertically elongate with upper portion wider and lower portion narrow), the presence of a conspicuous wide lateral band, conspicuous caudal spot, anal-fin rays iii-iv,19 to 23; pectoral-fin rays i,10 to 12; pelvic-fin rays i,7; lateral line scales 37 to 39; scale rows between dorsal-fin origin and lateral line 6 or 6 ½; scale rows between lateral line and pelvic-fin origin 4 or 5; predorsal scales 10 to 13; scale rows around caudal peduncle 14 to 16; outer row of premaxilla with pentacuspid teeth; inner premaxilla row with heptacuspid teeth; one maxillary tooth tri- to pentacuspid; 18 to 22 branched anal-fin rays; 20 gillrakers (1 c&s); body depth 32.3-37.5% SL; pelvic-fin length 13.6-17.1% SL; dorsal-fin length 21.1- 25.4% SL (more characters can be seen in Table 1). However we found some differences respect to the original description (OD): dorsal-fin rays 3i,8 to 9 (first unbranched ray very small vs. 2i,9; scale sheath along anal-fin base 8-12 scales vs. 6-10 scales (OD); shorter caudal peduncle length 12.6- 13.5% SL vs. 13.3-15.9 (OD); longer snout length 25.0-27.9 % HL vs. 19.0-24.0 (OD); shorter orbital diameter 30.5-32.0 % HL vs. 32.1-36.6 (OD); absence of bony hooks in all fins of males vs. presence in anal and pelvic-fin rays (OD); branched anal-fin rays 19-23 vs. 18-22 (OD).

Morphometric data used in the original description of A. xiru by Lucena et al. (2013) only include the type series from Laguna dos Patos system. However, these authors noted that the additional specimens from the río Uruguay basin were similar to those of type material. Because there is no data available from these additional specimens in the original description, we cannot say whether the differences found in our specimens are indicators of an intraspecific variation .

Figures

fig. 1. Astyanax xiru, uppon capture, MLP 10919, arroyo Fortaleza, affluent of the arroyo Yabotí-Guazú