Astyanax xiru Lucena, Castro & Bertaco, 2013

de Lucena, Carlos A. S., Castro, Jonas Blanco & Bertaco, Vinicius A., 2013, Three new species of Astyanax from drainages of southern Brazil (Characiformes: Characidae), Neotropical Ichthyology 11 (3), pp. 537-552 : 544-546

Astyanax xiru Lucena, Castro & Bertaco , new species Figs. 7-8

Astyanax obscurus Bertaco & Lucena, 2010: 11 (in part).

Holotype. MCP 19986 , 95.7 mm SL, Brazil, Rio Grande do Sul, Sapiranga, rio Feitoria, rio Caí drainage, 29º38’10”S 51º00’28”W, May 1996, D. Jacobus, L. F. B. Moreira & G. von Mülhen.

Paratypes. Brazil, Rio Grande do Sul State, laguna dos Patos system. MCN 19583, 2, 78.7-84.3 mm SL , MCP 20008 , 10 (5, 78.5-89.2 mm SL) , UFRGS 17099 , 2 , 80.0-82.0 mm, arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 15 Mar 1997 , D. Jacobus & A. Fialho. MCP 18699 , 1 , 93.5 mm SL, rio Saltinho, Vacaria , ca. 28º30’S 50º56’W, 24 Sep 1995 , C. Silveira & P. Reiman. MCP 19950 , 3 , 85.0- 98.2 mm SL, arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 10 Apr 1996 , D. Jacobus & A. Fialho. MCP 19962 , 3 , 52.9-95.7 mm SL, arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 18 May 1996 , D. Jacobus, L. Moreira & G. von Mülhen. MCP 19964 , 1 , 97.4 mm SL, arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 23 Nov 1996 , D. Jacobus, A. Fialho & L. Moreira. MCP 19978 , 9 (4, 81.5-99.3 mm SL), arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 9 Feb 1997 , D. Jacobus, A. Jacobus & A. Fialho. MCP 20005 , 1 , 91.0 mm SL, arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 14 Sep 1996 , D. Jacobus & A. Fialho. MCP 20016 , 3 , 84.3-109.3 mm SL, arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 17 Aug 1996 , D. Jacobus, L. Moreira & G. von Mülhen. MCP 20046 , 5 (3, 70.5-80.3 mm SL), arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W, 18 Dec 1996 , D. Jacobus & A. Fialho. MCP 21327 , 1 , 70.5 mm SL, arroio Feitoria, Sapiranga , ca. 29º34’S 51º00’W , 1997, D. Jacobus & A. Fialho. MCP 21730 , 12 (2, 58.1-70.6 mm SL c&s), stream between Dois Irmãos and Morro Reuter, at Travesso , ca. 29º33’S 51º06’W, 4 Sep 1991 , Ictiology team UFRGS (cited as A. obscurus by Bertaco & Lucena, 2010). MCP 32354 , 5 , 26.7-70.1 mm SL, rio Tainhas border of São Francisco de Paula and Jaquirana , 28º52’06”S 50º27’33”W, 14 Feb 2003 , V. A. Bertaco & A . R. Cardoso . MCP 33580 , 4 , 70.5-86.9 mm SL (1, 70.5 mm SL c&s), rio do Cachaço, near mouth of rio das Antas, Nova Roma do Sul , 29º02’44”S 51º26’37”W , 2003, J. Latini, J. R. Gonçalves & V. Capatti . MCP 33666 , 5 (3, 72.5- 87.2 mm SL), rio São Roque , near mouth of rio das Antas, 29º03’48”S 51º25’37”W , 2003, J. Latini, J. R. Gonçalves & V. Capatti . MCP 43547 , 1 , 83.7 mm SL, córrego Inferno, Antônio Prado , 28º52’34”S 51º18’59”W, Jul 2008 , J. Latini, J. R. Gonçalves & V. Capatti . MCP 47387 , 1 , 80.3 mm SL, Quaresma, near rio das Antas, Antônio Prado , 28º52’46”S 51º19’12”W , 2003, J. Latini, J. R. Gonçalves & V. Capatti .

Additional material (non-types). Brazil, rio Uruguay drainage, Rio Grande do Sul State. MCP 10855 (2, 90.2-91.1 mm SL), river on the road Coimbra to Santo Ângelo , Santo Ângelo , ca. 28º24’S 54º18’W. MCP 37065 , 1 , 56.4 mm SL, arroio Limoeiro, tributary of rio Ijuí, 16 de Novembro, 28º11’41”S 55º01’14”W. MCP 41490 , 6 (2, 67.5-81.9 mm SL), rio do Ouro, rio Forquilha drainage, Paim Filho, 27º41’06”S 51º42’10”W. Santa Catarina State. MCP 20874 , 65 (7, 67.0- 80.1 mm SL), arroio Lageado Grande, ca. 3 km of Linha Santana, on the road Santa Helena/Descanso, 26º53’35”S 53º36’04”W. MCP 40007 , 2 , 55.8-88.8 mm SL, riacho in the bridge at Nova Ibiaçá, Serra Alta, 26º51’42”S 53º00’09”W. MCP 40119 (4, 73.6-89.8 mm

SL), rio Saudade , bridge in Modelo to BR-282, 26º46’10”S 53º02’43”W. MCP 40124 , 45 (4, 65.7-99.2 mm SL) , rio Burro Branco , border Serra Alta and Sul Brasil, 26º41’12”S 52º49’02”W .

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 fins (vs. absence). The following combination of characters distinguish A. xiru from all others species of the genus (including the species complex A. bimaculatus and A. scabripinnis ): the presence of two conspicuous humeral spots (the first humeral spot vertically elongate with upper portion wider and lower portion narrow), the presence of a conspicuous wide lateral band, 18- 22 branched anal-fin rays, 19-24 gill rakers on first branchial arch, 37-40 perforated lateral line scales, 4-5 scale row between lateral line and pelvic-fin origin, outer row of premaxilla with pentacuspid teeth, inner premaxilla row with heptacuspid teeth, one maxillary teeth tri- to pentacuspid, very few small hooks on anal and pelvic fin of males, conspicuous caudal spot, head length 24.2-27.3% of SL, body depth 32.5-37.5% of SL, interorbital width 29.8-34.2% of HL, orbital diameter 32.1- 36.6% of HL, head length 24.2-27.3% of SL, and anal-fin base length 23.3-27.4% of SL.

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 asymmetric five cups (3+1+1) and the last with five or six cusps; central cusp twice as long and broad as others cusps. Maxilla with one tooth, tri- to pentacuspid, with central cusp longer. Dentary with nine to ten teeth. Five anteriormost dentary teeth decreasing gradually, hexa- to heptacuspid; remaining four or five smaller, tetra- or pentacuspid; last two unicuspid. Central cusp in all teeth two anal-fin base 6-10 scales, in single series, covering base of anteriormost rays.

Precaudal vertebrae 18(1) or 19(2); caudal vertebrae 16(1), 18 (1), or 19(1); total vertebrae 35(1), 36(1), or 38(1). Supraneurals 5(2). Gill-rakers upper branch 7(8), 8(24)*, or 9(3), lower branch 11(1), 12(2), 13(18), or 14(14); total number 19(3), 20(6), 21(10), 22(15)*, or 23(1).

to three times as long and broad as other cusps. All cusp tips slightly curved posteriorly towards inside mouth ( Fig. 8 ).

Dorsal-fin rays ii,9(36); first unbranched ray approximately one third to half length of second ray. Distal margin of dorsal-fin nearly straight to somewhat convex. Dorsal-fin origin approximately at middle of SL. Adipose fin slightly anterior at vertical through last anal-fin ray insertion. Anal-fin rays iii-v, 18(1), 19(5), 20(16)*, 21(7), or 22 (5). First unbranched ray normally only apparent in c&s specimens. Anal-fin profile smoothly concave. Anal-fin origin posterior to vertical through base of last dorsal-fin ray. Pectoral-fin rays i,11(8)*, 12(20), or 13(6). Pectoral-fin tip reaching one or two scales before vertical through pelvic-fin insertion. Pelvic-fin rays i,7(34), or 8(2). Pelvic-fin origin slightly anterior to vertical through dorsal-fin origin. Pelvic-fin tip extend beyond the genital opening but not reach the anal-fin origin. Caudal fin forked, lobes similar in size, rounded, i,17,i principal rays. Dorsal procurrent rays 10-11, and ventral procurrent rays 8-10 (n = 2).

Lateral line complete with 37(7), 38(11), 39(16), or 40(1) scales. Scale rows between dorsal-fin origin and lateral line 6(21)*, or 7(14); scale rows between lateral line and pelvic-fin origin 4(9), or 5(26)*. Predorsal scales 11(12), 12(15), or 13(8) arranged in regular series. Scale rows around caudal peduncle 14(16)*, 15(12), or 16(7). Axillary scale on pelvic-fin origin extends posteriorly covering two scales. Scale sheath along Color in alcohol. Dorsal and dorsolateral portions of head and body dark brown. Dark chromatophores scattered on lateral portion of head, more densely concentrated on snout and anterior border of eye. Dorsal portion of body densely pigmented in larger specimens.Body with black, midlateral stripe extending from the second humeral spot to caudal-fin base; dark pigmentation present on middle caudal-fin rays. Midlateral body stripe expanded dorsally and ventrally to caudal-fin base, forming small caudal spot. Two humeral spots. Anterior one, conspicuous, vertically elongate with superior portion wider, located over third to four vertical series of scales, extending over two to three horizontal series of scales above lateral line; inferior portion of spot narrow, sometimes with constriction at the junction with the upper portion (one to two scales pigmented), extending over one or two horizontal series of scales below lateral line. Second humeral spot large, evident, not ventrally surpassing lateral line, extending over three horizontal series and two to three vertical series of scales. Region between spots pale. Fins with dispersed dark chromatophores ( Fig. 7 ).

Sexual dimorphism. Males with small, fine and delicate, bony hooks on the anal- and pelvic-fin rays. One bony hook per lepidotrichia, rarely one pair, from the first to seventh anal-fin branched rays; maximum seven hooks per ray. Hooks on the pelvic-fin are distributed in second to fourth branched rays. Gill glands ( Burns & Weitzman, 1996) were not found macroscopically on first gill arch in either males or females.

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.

Etymology. The specific epithet xiru , from Tupi-Guarani, means an old wise Indian. Word used mainly in the treatment personal in the countryside of Rio Grande do Sul State.

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. 29º35’S 51º06’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. 29º34’S 51º00’W.

Figures

Fig. 7. Astyanax xiru, new species, MCP 19986, 95.7 mm SL, holotype, rio Feitoria, rio Jacuí drainage, Sapiranga, Rio Grande do Sul, Brazil.

Fig. 8. Astyanax xiru, new species, MCP 33580, 70.5 mm SL, paratype, upper and lower jaws teeth, left side, lateral view. Scale bar = 1 mm.

Fig. 9. Map of southern Brazil and Uruguay, showing the distribution of the material examined of Astyanax xiru. Some symbols represent more than on lot or locality. Black circle = type locality.