Astyanax laticeps ( Cope, 1894 )

Bertaco, Vinicius A. & de Lucena, Carlos A. S., 2010, Redescription of Astyanax obscurus (Hensel, 1870) and A. laticeps (Cope, 1894) (Teleostei: Characidae): two valid freshwater species originally described from rivers of Southern Brazil, Neotropical Ichthyology 8 (1), pp. 7-20 : 12-15

Astyanax laticeps ( Cope, 1894)

Figs. 4b , 6-8

Tetragonopterus laticeps Cope, 1894:89 . Type locality: Rio Grande do Sul, Brazil (restricted to laguna dos Patos system by Malabarba, 1989:130).

Astyanax laticeps . - Fowler, 1906:348 (designation of the holotype). - Bertaco & Malabarba, 2001:233 (valid species, morphometric and meristic data of the types).

Diagnosis. Astyanax laticeps belongs to the A. scabripinnis species complex and is distinguished from all species of this complex, except A. troya , by the presence of one horizontally elongate black humeral spot with a narrow anteroventral downward extension past the lateral line. Astyanax laticeps differs from A. troya by the presence of one humeral spot (vs. two), one to three maxillary teeth with one to three cusps (vs. one pentacuspid tooth), and the presence of bony hooks only on anal and pelvic fins (vs. present in all fins, except pectoral fin of males). A similar oval humeral spot can be found in A. jacuhiensis (a sympatric species and member of the A. bimaculatus species group sensu Garutti, 1995). Astyanax laticeps differs from A. jacuhiensis by the absence of two bars in the humeral region, presence of a narrow anteroventral downward extension of the humeral spot past the lateral line, and one to three maxillary teeth (vs. maxillary teeth absent). Note the differences between A. laticeps and A. obscurus in the diagnosis above. Astyanax laticeps differs from the holotype of A. scabripinnis by the predorsal distance (49.4-55.7 vs. 57.7% of SL), anal fin base length (21.3-28.7 vs. 30.2% of SL), and pelvic fin length (14.3-21.8 vs. 22.1% of SL).

Description. Morphometric data summarized in Tables 1-2. Body compressed and elongate; greatest body depth usually anterior to dorsal-fin origin. Dorsal profile of head between vertical through posterior nostril and tip of supraoccipital spine straight. Dorsal body convex profile from tip of supraocciptal 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 insertion, nearly straight from that point 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. Head small. Mouth terminal. Maxilla extending posteriorly to vertical through anterior margin of orbit, slightly curved, and aligned at an angle of approximately 45 degrees relative to longitudinal body axis. Maxilla slightly widened posteriorly.

Two tooth rows in premaxilla; outer row with four to five* tricuspid teeth with central cusp longer; rarely, the most lateral teeth with two additional very small cusps. Five teeth in inner premaxillary row; teeth gradually decreasing in length from first to fourth teeth with last tooth distinctly smaller: teeth with three to five cusps with central cusp twice as long and broad as other cusps; rarely, two most lateral cusps present, but visible only in c&s specimens. Maxilla with one to three (two to three*) teeth with one to three cusps, with central cusp longest. Four anteriormost dentary teeth larger, with five cusps, followed by five to seven small teeth with one to three cusps. Central cusp in all teeth two 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* (two specimens with ii,8, and five with ii,10, n = 140); first unbranched ray approximately half the length of second ray. Distal margin of dorsal fin nearly straight or slightly convex. Dorsal fin origin approximately at middle of SL. Adipose fin approximately at vertical through last anal-fin ray insertion.Anal-fin rays iii-v,15-23 (18-21*, mean = 19.5, n = 140). First unbranched ray normally only apparent in c&s specimens.Anal fin origin posterior to vertical through base of last dorsal-fin ray. Pectoral-fin rays i,10-14 (i,11-12*, mean = 12.2, n = 140). Pelvic-fin rays i,7* (n = 140). Pelvic fin origin slightly anterior to vertical through dorsal fin origin. Caudal fin forked, lobes similar in size, 19* principal rays. Dorsal procurrent rays 11-13, and ventral procurrent rays 10-11 (n = 14).

Lateral line complete with 37-40 scales (37-38*, mean = 37.0, n = 125). Scale rows between dorsal fin origin and lateral line 6-8 (6*, mean = 6.8, n = 136); 4-6 scale rows between lateral line and pelvic fin origin (5*, mean = 5.2, n = 137). Predorsal scales 9-14 (11-12*, mean = 11.0, n = 117) arranged in regular series. Scale rows around caudal peduncle 14-18 (14-16*, mean = 16.8, n = 121). Axillary scale on pelvic fin origin extends posteriorly covering 2-3 scales. Scale sheath along anal fin base 6-14 scales, in single series, covering base of anteriormost rays.

Precaudal vertebrae 17-18; caudal vertebrae 17-19; total vertebrae 35-37 (n = 15). Supraneurals 5-7 (n = 15). Gill-rakers upper branch 6-10 (mean = 8.2, n = 135), lower branch 11-16 (mean = 13.2, n = 135).

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. Scales midlateral and below the lateral line bordered with dark brown chromatophores forming reticulate pattern. Body with black, midlateral stripe extending from the humeral spot to caudal fin base; faint dark pigmentation present on middle caudal-fin rays. Midlateral body stripe expanded dorsally and ventrally to caudal fin base, forming small caudal spot. Humeral spot, conspicuous, horizontally elongate located over 3 to 5 vertical series of scales and extending over 2 horizontal series of scales above of the lateral line; with a narrow anteroventral downward extension past lateral line and extending over one, rarely two, vertical series of scales ( Figs. 4b and 7 ). Humeral spot can vary in shape with upper portion almost rounded or slightly wider than lower portion in small specimens around 40.0 mm SL (MCP 40807, and MUCP 940) and occasionally in large specimens (53.1 mm SL, MUCP 3250, and 66.8 mm SL, MCP 34533). Fins with dispersed dark chromatophores. Specimens a few days fixed in formalin (MCP 33312), all fins red-orange pigmented.

Sexual dimorphism. Males with thick, well-developed retrorse bony hooks on pelvic-fin and anal-fin rays. One paired bony hook per lepidotrichia in the last unbranched anal-fin ray and first to eighth anal-fin branched rays on middle and distal portions of rays. One paired bony hook per lepidotrichia on entire first to sixth pelvic-fin branched rays. Anal fin profile slightly concave to straight in males, concave in females. In males up to 60 mm SL, tip of pelvic fin reaches or slightly passes the anal fin origin, and tip of pectoral fin extends beyond the pelvic fin origin. In females, both fins do not reach the anal and pelvic fin origins, respectively. Gill glands ( Burns & Weitzman, 1996) were not found macroscopically on first gill arch in either males or females.

Distribution. Astyanax laticeps is known from the coastal drainages of Uruguay (arroyo Don Carlos) and Brazil to south of the Paraná State (rio Cubatão draining to baía de Guaratuba), and rio Uruguay drainage ( Fig. 5 ). This finding substantially extends the distribution of the species reported by Azpelicueta & Loureiro (2009).

Geographic variation. All meristic characters analyzed among A. laticeps populations showed wide overlap, except for three counts (lateral line and caudal peduncle scales, and branched anal-fin rays). Kruskal-Wallis nonparametric multiple comparisons indicate significant differences between population samples. Dunn’s method shows differences in the number of lateral line scales between the rio Cubatão Norte and rio Itapocu populations and other populations, except that from the rio Tramandaí drainage ( Fig. 9 ). The same count was not significantly different between the rio Cubatão and rio Itapocu populations. In the counts of scales around the caudal peduncle, the rio Cubatão Norte population was significantly different from all other populations, except the rio Itapocu ( Fig. 10 ). The same pattern occurred in the number of branched anal-fin rays between the rio Cubatão Norte and other populations, except the rio Itapocu. This count was significantly different between the rio Itapocu and other populations, except the rio Mampituba ( Fig. 11 ). Significant differences were found in the number of lateral line scales between the rio Mampituba and rio Tubarão populations and the others, except the rio Itajaí and laguna dos Patos system.

The morphometric data analyzed by percentages and PCA did not reveal at all the discriminate populations ( Figs. 12-14 , Table 3). The Mampituba population can be partially discriminated from those of the laguna dos Patos, Tramandaí, and Itapocu drainages. The variables that most influenced the discrimination on the third axis (explaining 0.89511% of the variance) were interorbital width and caudal peduncle length on the positive side and anal fin base length and snout length on the negative side ( Fig. 12 ). When only females were analyzed, the populations of the Tramandaí and Mampituba drainages can be partially discriminated from each other. The most influenced measurement was the caudal peduncle length and interorbital width on the negative side on the second axis (explaining 0.7729% of the variance) and the anal fin base length and snout length on the positive side ( Fig. 13 ). The PCA for males showed that the populations Tramandaí and Mampituba, and Itajaí and Cubatão Norte drainages are discriminated from each other on the second axis (explaining 2.4185% of the variance) ( Fig. 14 ). Pectoral and pelvic fin lengths were the variables that were influenced most on the negative side, and snout length and body depth on the positive side.

Despite the above-mentioned differences, there is overlapping of ranges of meristic and percentage data. In the meristic data analyzed, the Itapocu and Cubatão Norte populations showed higher median values compared to the other populations, suggesting that these populations may be distinct. However, there is overlapping of the extreme values of these characters when compared with southern populations. Besides, no diagnostic characters were found to discriminate the Itapocu and Cubatão Norte populations from the others. The few differences in PCA did not show any rational geographic pattern in the entire distribution area of the species. Therefore, we considered all populations analyzed as Astyanax laticeps .

Among the discerning taxonomic studies, including species widely distributed in the coastal rivers of south and southeast Brazil, only Mimagoniates microlepis (Steindachner) showed a distribution similar to that of A. laticeps ( Weitzman et al., 1988; Menezes & Weitzman, 1990, 2009). Weitzman et al. (1988) found divergent live color patterns between some isolated populations of M. microlepis , and related this divergence to the possible initial process of speciation. In the present study, the tendency toward higher median values for the populations from Itapocu and Cubatão drainages could be indicative of the same early process.

Material examined. Holotype. ANSP 21852 (54.1 mm SL), Rio Grande do Sul, Brazil, 1882, H. H. Smith . Paratypes. ANSP 21743 , 4 (4, 38.0- 50.8 mm SL), same data of holotype. Non-types: Brazil: Rio Grande do Sul: laguna dos Patos system: rio Jacuí drainage : UFRGS 6649 , 3 (53.1-61.3 mm SL) , UFRGS 6651 , 2 (56.6-61.8 mm SL), swamp on the area designed to Condomínio Alphaville, lago Guaíba basin, Porto Alegre . MCP 8246 , 4 (2, 51.1-68.2 mm SL) , MCP 10140 , 3 (2, 68.4-72.9 mm SL), açude dos Peruffo, Vila Nova, Bento Gonçalves . MCP 8959 , 25 (2, 52.4-56.5 mm SL), Linha Nova, Pirajá, Nova Petrópolis . MCP 15035 , 5 (2, 87.8-92.5 mm SL), arroio Caguas . MCP 16564 , 26 (5, 47.3-63.7 mm SL), stream and small dam on the Chácara do Seminário de Fazenda Souza , Caxias do Sul . MCP 17321 , 5 (4, 53.5-77.2 mm SL), arroio Taquara, Lizete Farm, Boa Vista road about 5 km of BR 290 , Minas do Leão . MCP 17345 , 4 (2, 52.6-52.9 mm SL), arroio Martins, road BR 290 , between Butiá and Minas do Leão, Butiá. MCP 18246 , 3 (2, 51.1-68.2 mm SL), arroio at São José locality, Restinga Seca . MCP 19833 , 8 (2, 95.3-106.8 mm SL), small dam near the road Minas do Leão to Dom Feliciano, Triunfo . MCP 19980 , 3 (3, 97.1-104.0 mm SL) , MCP 19983 , 2 (2, 95.3-106.8 mm SL) , MCP 20019 , 1 , 96.7 mm SL, arroio Feitoria, Sapiranga . MCP 20052 , 3 (2, 92.0- 95.6 mm SL), arroio Feitoria, Ivoti . MCP 21269 , 1 (1, 45.5 mm SL), arroio Passo das Éguas, on road between Tunas and Jacuizinho, Tunas. MCP 22759 , 1 , 80.0 mm SL, arroio Tipiáia, about 13 km N of Júlio de Castilhos, on road to Cruz Alta, Júlio de Castilhos . MCP 23007 , 1 (1, 63.5 mm SL), arroio Bom Jardim, III Pólo Petroquímico, Triunfo . MCP 26127 , 8 (8, 68.1-84.2 mm SL), arroio Cadeia, Santa Maria do Herval . MCP 26539 , 3 (2, 62.0-83.0 mm SL), tributary of rio Jacuí at Nova Boêmia, Agudo . MCP 27772 , 2 , 60.7-69.6 mm SL, lajeado do Gringo at Linha das Pedras, Ibarama . MCP 28118 , 1 , 69.3 mm SL, arroioAmoras, Viamão . MCP 28954 , 2 , 53.0- 60.7 mm SL, arroio Tolloti, tributary of arroio dos Ratos, Mariana Pimentel . MCP 30890 , 4 , 47.4-77.1 mm SL, arroio Caçador, Canela . MCP 32452 , 1 , 59.2 mm SL, tributary of rio Morungava, rio Gravataí basin, Morungava . MCP 33312 , 11 , 28.6 - 53.0 mm SL, tributary of the rio Ivaí in the PCH Eng. Ernesto Jorge Dreher, Júlio de Castilhos . MCP 35425 , 5 , 58.6-61.5 mm SL, tributary of rio Ivaí, Júlio de Castilhos . MCP 33678 , 1 , 56.5 mm SL, passo do inferno, tributary of rio Taquari , Antônio Prado . MCP 34533 , 3 , 45.4-65.9 mm SL, tributary of arroio Grande, Mariana Pimentel . MCP 34803 , 4 , 34.5 -65.0 mm SL, arroio dos Ratos, São Jerônimo . MCP 34553 , 3 , 43.3 -67.0 mm SL, tributary of arroio Grande, Mariana Pimentel . MCP 34802 , 17 , 26.8-73.4 mm SL, headwaters of arroio Quitéria, tributary of arroio dos Ratos, São Jerônimo . MCP 40513 , 2 , 29.9-36.3 mm SL, rio Cadeia, bridge at 3 km from Jacaré beach, Santa Maria do Herval . MCP 42762 , 3 , 48.6-68.5 mm SL, arroio Pedacino, Caxias do Sul . UFRGS 6815 , 7 , 21.2-41.1 mm SL, arroio Lava Pés, São Francisco de Paula . UFRGS 8191 , 50 , 27.3-74.1 mm SL, tributary of rio Capivari , Bota Farm, Encruzilhada do Sul . UFRGS 8789 , 20 , 36.3-77.2 mm SL, tributary of arroio Iruí at Limoeiro Farm, Rio Pardo. Rio Camaquã drainage : MCP 25753 , 8 (3, 55.7-71.8 mm SL), arroio Maria Ulghim, Camaquã . MCP 25763 , 1 , 38.3 mm SL, tributary of arroio das Neves, Santana da Boa Vista . MCP 39210 , 7 , 21.1-64.6 mm SL , MCP 39213 , 37 , 18.4-64.8 mm SL , MCP 39216 , 4 , 21.9-47.5 mm SL, arroio on the road to Chafri farm, Boqueirão, Encruzilhada do Sul . MCP 40807 , 23 , 18.0- 53.4 mm SL, tributary of arroio das Lavras on the road between Lavras do Sul and Bagé, Lavras do Sul . MUCP 940 , 26 (3, 55.1-61.5 mm SL), arroio do Padre, Arroio do Padre. São Gonçalo drainage : MCP 20548 , 7 (1, 63.6 mm SL) , MCP 25129 , 7 , 30.2-44.6 mm SL, stream on the road between Pedro Osório and Basílio, Pedro Osório. MCP 20841 , 1 , 25.7 mm SL, arroio Reduzinho between Pedro Osório and Basílio, Pedro Osório. MCP 25117 , 8 (2, 54.5-56.4 mm SL), arroio Paraguaia about 3 km of Pinheiro Machado, Pinheiro Machado . MCP 34763 , 1 , 56.0 mm SL, tributary of arroio Paraguaia, Pinheiro Machado . MCP 34734 , 1 , 38.8 mm SL, arroio Mata Olho on the road between Pedro Osório-Basílio, Pedro Osório . MCP 34736 , 1 , 62.0 mm SL, headwaters of arroio Alegria, Pedras Altas . MCP 34739 , 7 , 28.4-41.2 mm SL, creek on the road Pedro Osório-Basílio, Pedro Osório . MCP 34761 , 2 , 46.2-46.3 mm SL, stream between Herval and Pedras Altas, Pedras Altas. MCP 34790 , 1 , 36.9 mm SL, arroio Arambaré between Pedro Osório and Herval, Herval. MUCP 639 , 1 (1, 93.9 mm SL), headwaters of sanga da Gama, Monte Bonito, Pelotas . MUCP 1098 , 1 (1, 78.9 mm SL), arroio Schwartz, Turuçu . MUCP 3222 , 18 , 29.8-48.2 mm SL, headwaters of the sanga do Sonho, Monte Bonito, Pelotas . MUCP 3228 , 1 (1, 50.5 mm SL), headwaters of arroio Candiotinha, Torrinhas, Pinheiro Machado . MUCP 3250 , 27 (10, 50.3-68.9 mm SL), headwaters of sanga do Vale, Cerro das Almas, Capão do Leão . MUCP 3330 , 14 , 37.6-49.5 mm SL, headwaters of rio Pelotas-Mirim,Canguçu. Rio Jaguarão drainage : MCP 27271 , 5 , 38.1-64.5 mm SL, arroio Quebra Jugo no passo dos Pinheiros, Candiota . UFRGS 3909 , 1 , 56.1 mm SL , UFRGS 4577 , 4 , 45.4-76.7 mm SL, arroio Quebra Jugo, Candiota . UFRGS 4719 , 10 , 28.8-51.9 mm SL , UFRGS 4575 , 31 , 15.5-63.4 mm SL , UFRGS 4576 , 10 c&s, 38.7-65.1 mm SL, arroio Poacá, Candiota. Other drainages in laguna dos Patos system : MCP 23842 , 4 (1, 62.2 mm SL), tributary of arroio Viúva Teresa, São Lourenço do Sul . MCP 23843 , 2 (2, 54.9-62.9 mm SL), tributary of arroio São Lourenço, São Lourenço do Sul . MCP 23844 , 2 , 26.3-32.4 mm SL, arroio Capivaras between Sentinela do Sul and Vila Aurora, Sentinela do Sul. Rio Uruguay drainage: Rio Grande do Sul : MCP 37200 , 10 , 33.1-44.3 mm SL, arroio Cinamomo, tributary of rio Ijuí , Roque Gonçalez . UFRGS 7036 , 1 , 36.8 mm SL, stream on the road to Pirapó, São Nicolau. Rio Tramandaí drainage: rio Maquiné drainage: Maquiné municipality : MCP 13600 , 7 (1, 65.9 mm SL) , MCP 14858 , 4 (2, 72.2-84.4 mm SL) , MCP 20987 , 8 (8, 66.8-82.0 mm SL) , MCP 25690 , 3 (3, 73.5-79.4 mm SL, 1 c&s, 58.0 mm SL) , MCP 25704 , 11 (6, 51.4-64.8 mm SL), arroio Água Parada, tributary of rio Maquiné . MCP 14306 , 2 (2, 65.7-67.1 mm SL), headwaters of rio Maquiné , about 2 km above Luca Mundo Novo dam . MCP 14790 , 10 (3, 46.5-65.1 mm SL) , MCP 25396 , 1 (1, 64.8 mm SL), arroio Pinheiro . MCP 20705 , 6 (3, 49.1-63.9 mm SL), tributary of rio Maquiné . MCP 20829 , 1 , 45.2 mm SL, rio Maquiné . MCP 25343 , 5 (5, 69.5-78.7 mm SL) , MCP 25406 , 6 (5, 62.3-88.5 mm SL) , MCP 25411 , 1, 100.5 mm SL , MCP 25420 , 3 (3, 68.6-81.2 mm SL) , MCP 25446 , 2 (1, 69.1 mm SL), arroio Ligeiro, Barra do Ouro . MCP 25368 , 3 (3, 57.3-61.9 mm SL) , MCP 25407 , 12 (7, 54.2-94.1 mm SL), Maquiné . MCP 25705 , 14 (8, 72.6-87.3 mm SL), arroio Encantado . MCP 25413 , 4 (4, 68.8-77.2 mm SL), tributary of rio Forqueta . MCP 25421 , 1 (1, 66.1 mm SL), rio Forqueta . MCP 25714 , 4 (4, 80.6-92.3 mm SL), tributary of left margin of rio Maquiné . UFRGS 4525 , 4 (2, 73.7-90.8 mm SL), rio Maquiné, Barra do Ouro. Rio Três Forquilhas drainage : MCP 10791 , 6 (6, 46.5-68.6 mm SL) , MCP 20830 , 1 , 45.2 mm SL, tributary of rio Três Forquilhas , Itati . MCP 14687 , 2 , 38.2-39.7 mm SL, rio Mitmann at Vila Nova, about 10 km of road BR 101 to Itati . MCP 14746 , 4 , 37.2-49.7 mm SL, rio do Padre at Itati . MCP 21091 , 1 (1, 68.1mm SL), headwaters rio Três Forquilhas , Três Forquilhas . MCP 25275 , 1 , 38.0 mm SL, rio Três Pinheiros on road to Vila Itati, about 7 km N of road BR 101 , Terra de Areia . UFRGS 4413 , 1 (1, 65.7 mm SL), rio Três Forquilhas . UFRGS 6317 , 1 , 68.4 mm SL , UFRGS 6646 , 2 , 78.4 -91.0 mm SL, stream at Reserva Biológica da Mata Paludosa, Terra de Areia. Rio Mampituba drainage : MCP 23719 , 1 , 33.0 mm SL, rio Negro on the road between Morrinhos do Sul and Praia Grande, Morrinhos do Sul. Santa Catarina: rio Mampituba drainage: Praia Grande : MCP 11502 , 9 (9, 27.3-66.5 mm SL), rio Faxinalzinho , Mãe dos Homens . MCP 14741 , 2 (2, 38.7-40.6 mm SL), arroio Facão, Mãe dos Homens . MCP 14750 , 3 (3, 59.3-81.3 mm SL), tributary of rio Canoas, about 2 km of Praia Grande . MCP 23552 , 2 (2, 36.2- 40.1mm SL), tributary of rio Sertão , Cachoeira, about 9 km NE of Praia Grande. MCP 23614 , 10 (10, 44.7-60.9 mm SL, 2 c&s, 58.1- 60.1 mm SL) arroio Maia Coco at Vila Rosa about 5 km NW of Praia Grande. Rio Araranguá drainage : UFRGS 6204 , 13 , 40.9-86.4 mm SL, rio Mãe Luzia, Treviso. Rio Tubarão drainage : MCP 10999 , 3 (3, 29.4-30.3 mm SL), mouth of rio Sanga daAreia, Tubarão . MCP 11013 , 5 , 24.2-28.9 mm SL, rio Capivari , near at Gravatal . MCP 11023 , 9 (8, 28.3-41.4 mm SL), tributary of rio Tubarão . MCP 11023 , 8 (8, 27.3-41.4 mm SL), tributary of rio Tubarão , Tubarão . MCP 11025 , 1 , 40.1 mm SL, rio Tubarão, near at Rio do Pouso . MCP 11028 , 40 (17, 27.3-77.2 mm SL), rio Sanga da Areia , Tubarão . MCP 17481 , 3 (3, 36.5-49.2 mm SL), tributary of rio Pinheiros on road SC 407, Anitápolis . MCP 17614 , 7 (5, 44.1-74.6 mm SL, 2 c&s, 52.4-54.2 mm SL), tributary of rio Pinheiros , Anitápolis . MCP 25585 , 2 (2, 66.4-97.1 mm SL), rio Capivari , São Martinho . UFRGS 6203 , 76 , 34.9-60.4 mm SL, rio Lageado on area of the USITESC, Urussanga. Rio Itajaí-Açu drainage : MCP 11504 , 12 (12, 44.1-63.3 mm SL), tributary of rio Itajaí , on road Blumenau to Rio do Sul, Ibirama . MCP 16487 , 2 (2, 45.6-47.8 mm SL), Ribeirão São Luis, tributary of rio Benedito Novo , Apiúna . MCP 16567 , 1 59.8 mm SL small stream on road between Taió and Passo Manso, Taió. MCP 21785 , 3 (3, 75.1-83.2 mm SL), rio Palmeira , Rio dos Cedros . MCP 21787 , 7 (7, 69.6-105.8 mm SL), rio dos Cedros, Rio dos Cedros. Rio Itapocu drainage : MCP 14508 , 30 (19, 49.7-92.2 mm SL), tributary of rio Itapocu, Corupá. Rio Cubatão Norte drainage (baía de São Francisco) : MCP 10707 , 7 (7, 46.5-72.4 mm SL), rio Prata , Joinville . MCP 11275 , 17 (10, 52.8-97.3 mm SL), arroio Lindo, Pirabeiraba, Joinville . MCP 11278 , 18 (13, 55.8- 86.4 mm SL), rio Seco , km 10 on road SC 280, Joinville . MCP 14048 , 13 (12, 46.7-84.2 mm SL, rio Garuvá on road BR 101 , about 2 km from Santa Catarina and Paraná boundary, Garuvá. Paraná: rio Cubatão drainage (baía de Guaratuba) : MCP 13665 , 1 (1, 65.4 mm SL), rio São João, Pedra Branca do Araraquara at BR 376 between Curitiba and Joinville, Pedra Branca. MCP 20375 , 1 (1, 85.9 mm SL), tributary of rio Cubatão , Guaratuba . MCP 41260 , 3 , 35.1-39.4 mm SL, rio Araraquara , BR 101 3 km N from Garuvá. Uruguay : UFRGS 2962 , 3 , 56.0- 65.2 mm SL, arroyo Don Carlos, laguna Castilhos drainage, coastal river drainage, Rocha, Departamento Rocha .

Figures

Fig. 4. Lateral view of left side of anterior region showing humeral spots of (a) Astyanax obscurus, MCP 26125, 75.6 mm SL, and (b) Astyanax laticeps, MCP 26127, 71.1 mm SL.

Fig. 6. Astyanax laticeps,ANSP 21852, holotype, 54.1 mm SL, Rio Grande do Sul, Brazil.

Fig.7.Astyanaxlaticeps,MCP35425,61.2 mmSL,tributary of rioIvaí,rioJacuí drainage,Júliode Castilhos,RioGrande doSul,Brazil.

Fig.8. Astyanax laticeps,UFRGS4576,male,49.2mmSL.SEM image of upper and lower jaws, right side. Scale bar = 1 mm.

Fig. 5. Map of southern Brazil and Uruguay, showing the distribution of examined material of Astyanax obscurus (circles), and Astyanax laticeps (squares). Some symbols represent more than one lot or locality.

Fig. 9. Tukey box plots of number of perforated scales of lateral line in Astyanax laticeps populations by river drainage from south to north. Mean represented by thick vertical bar and 25th and 75th percetiles as lateral borders of box plots.

Fig. 10. Tukey box plots of number of scales around the caudal peduncle in Astyanax laticeps populations by river drainage from south to north. Mean represented by thick vertical bar and 25th and 75th percetiles as lateral borders of box plots.

Fig. 11. Tukey box plots of number of branched anal-fin rays in Astyanax laticeps populations by river drainages from south to north. Mean represented by thick vertical bar, and 25th and 75th percetiles as lateral borders of box plots.

Fig. 12. Projection of individual scores in the space of first and third Principal Component axis for the populations of males and females of Astyanax laticeps.

Fig. 13. Projection of individual scores in the space of first and second Principal Component axis for the populations of females of Astyanax laticeps.

Fig. 14. Projection of individual scores in the space of first and second Principal Component axis for the populations of males of Astyanax laticeps.