Astyanax jordanensis, Vera Alcaraz & Pavanelli & Bertaco, 2009

Vera Alcaraz, Héctor S., Pavanelli, Carla S. & Bertaco, Vinicius A., 2009, Astyanax jordanensis (Ostariophysi: Characidae), a new species from the rio Iguaçu basin, Paraná, Brazil, Neotropical Ichthyology 7 (2), pp. 185-190: 186-188

publication ID

1982-0224

persistent identifier

http://treatment.plazi.org/id/03B387A3-8F76-FFCE-1775-FCA602980225

treatment provided by

Carolina

scientific name

Astyanax jordanensis
status

new species

Astyanax jordanensis   , new species

Figs. 1-2

Holotype. MZUSP 99137 View Materials , 47.7 mm SL, male, Brazil, Paraná, município de Candói, rio Iguaçu basin, middle rio Jacu (25°37’S 52°03’W), 23 Aug 1995, Nupélia & Copel. GoogleMaps  

Paratypes. All from Brazil, Paraná, rio Iguaçu basin. MCP 41914 View Materials , 10 View Materials , 58.7-68.6 mm SL; MHNCI 11714 View Materials , 10 View Materials , 31.5 View Materials -63.0 mm SL (2, 60.7-62.9 mm SL); MZUSP 99138 View Materials , 12 View Materials , 42.7-76.1 mm SL; NUP 1681, 27, 23.0- 68.2 mm SL (13, 39.2-68.2 mm SL); NUP 5242, 1 c&s, 47.7 mm SL; all collected with holotype. MCP 41915 View Materials , 4 View Materials , 42.6 View Materials - 47.0 mm SL (1 c&s); NUP 5245, 1 c&s, 47.8 mm SL; NUP 5248, 3, 42.3-45.1 mm SL; all from município de Candói, upper rio Jacu , 23 Aug 1995, Nupélia & Copel. NUP 5251, 4, 67.0-72.0 mm SL, município de Reserva do Iguaçu , rio das Torres, 25 Sep 1995, Nupélia. NUP 5252, 1, 68.5 mm SL, município de Reserva do Iguaçu , rio das Torres, 22 Jan 1996, Nupélia GoogleMaps   .

Diagnosis. Astyanax jordanensis   fits the definition of the Astyanax scabripinnis   species complex of Bertaco & Lucena (2006), which are: body deepest and heaviest in area proximate to middle of pectoral fins, head heavy, snout short and abrupt by tapering, body shallower than 41% of SL, anal fin with 13-21 branched rays, presence of one or two humeral spots, and a dark midlateral body stripe extending to the tip of the middle caudal-fin rays. The new species differs from congeners of the A. scabripinnis   species complex by having fewer branched anal-fin rays [13-17 vs. more than 17 in A. ita   ; A. laticeps (Cope, 1894)   ; A. ojiara Azpelicueta & Garcia, 2000   ; A. paris Azpelicueta, Almirón & Casciotta, 2002   ; A. scabripinnis (Jenyns, 1842)   ; and A. troya Azpelicueta, Casciotta & Almirón, 2002   ], more lateral line scales [35-38 vs. 34-35 in A. jenynsii (Steindachner, 1877)   ], the possession of one humeral spot [vs. two in A. brachypterygium Bertaco & Malabarba, 2001   ; A. cremnobates Bertaco & Malabarba, 2001   ; A. leonidas   ; A. obscurus (Hensel, 1870)   ; and A. rivularis (Lütken, 1875)   ], and the shape of the dentary teeth (abruptly decreasing in size after the fifth tooth vs. teeth gradually decreasing in size posteriorly in A. intermedius Eigenmann, 1908   ). Astyanax jordanensis   differs from A. microschemos Bertaco & Lucena, 2006   by a smaller orbital diameter (22.6- 29.1% vs. 29.7-34.1% of HL), a greater snout length (25.3- 29.7% vs. 19.8-25.6% of HL), by having more predorsal scales (12-15 vs. 10-12); from A. paranae Eigenmann, 1914   by having a greater interorbital width (30.6-35.7% vs. 25.8-30.3% of HL), and more branched anal-fin rays (13-17 vs. 17-22); from A. totae   by a greater snout length (25.3-29.7% vs. 14.6-24.1% of HL), by having more dorsal procurrent rays (10-12 vs. 7), and fewer maxillary teeth (1 or 2, usually 1 vs. 2 to 5, usually 3); from A. varzeae   (included in the A. scabripinnis   species complex by Abilhoa & Duboc, 2007) by the smaller orbital diameter (22.6-29.1% vs. 30.9-44.5% of HL), a greater snout length (25.3-29.7% vs. 16.4-23.3% of HL), by having more dorsal procurrent rays (10-12 vs. 8 or 10), fewer lateral line scales (35-38 vs. 37-42), and by the possession of one humeral spot (vs. two), and from A. burgerai   (described and included in the A. scabripinnis   species complex by Zanata & Camelier, 2009) by presenting a conspicuous midlateral band from humeral region to caudal peduncle (vs. inconspicuous), more branched anal-fin rays (13-17 vs. 18-19), and more lateral line scales (35-38 vs. 31-34).

Description. Morphometric data for Astyanax jordanensis   presented in Table 1. Body compressed and elongate; greatest body depth usually located anterior to dorsal-fin origin. Dorsal profile of body convex from snout to dorsal-fin origin, nearly straight along dorsal-fin base, straight or slightly concave from last dorsal-fin ray to adipose fin. Ventral profile of body convex from mouth to anal-fin origin, nearly straight along anal-fin base. Caudal peduncle elongate and nearly straight to slightly concave along both dorsal and ventral margins.

Head small. Mouth terminal, lower jaw slightly shorter than upper jaw. Maxilla extending posteriorly to vertical through middle of orbit, slightly curved, and forming angle of about 45 degrees relative to longitudinal body axis.

Premaxilla with two teeth rows, outer row with 3(7), 4*(28), or 5(2) teeth with three to five cusps. Inner premaxillary row with 5*(40) teeth, symphysial teeth with four cusps, second and third teeth with four to seven cusps and two posterior most teeth smaller with three to five cusps. Maxilla with 1*(25) or 2(14) teeth with three cusps. Dentary with the four anterior most teeth larger, with five to seven cusps. Large teeth of dentary followed by six to eight smaller teeth with one to three cusps, gradually decreasing in size.All teeth with central cusp longer than lateral cusps ( Fig. 2). Gill rakers on dorsal limb of outer gill arch 6(3), and on ventral limb 10(2) or 11(1).

Dorsal-fin rays i,9(3), ii,9*(33); first unbranched ray shorter when present, approximately half length of second ray. Additional very small first ray, iii,9(6) observable only in c&s and radiographed specimens. Dorsal-fin pterygiophores 10(2) or 11(1). Mature males with small bony hooks on distal onethird of first to fifth branched rays. Dorsal-fin origin posterior to middle of body, and posterior to vertical through pelvic-fin origin. Adipose fin small, located approximately at vertical through base of last anal-fin ray. Pectoral-fin rays i,9(6), i,10*(14), i,11(23), or i,12(2). Pectoral-fin origin situated anterior to posterior margin of opercle. Tip of pectoral fin reaching pelvic-fin origin in males, and reaching approximately three quarters of distance between pectoral- and pelvic-fin origins in females. Mature males with small bony hooks on distal portion of first to eighth branched rays. Pelvic-fin rays i,6*(34) or i,7(11). Pelvic fin of males usually bearing small bony hooks along ventromedial border of first to fourth branched rays. Pelvic-fin origin located anterior to vertical through dorsalfin origin. Tip of pelvic fin reaching anal-fin origin in males, falling short of that point in females. Anal-fin rays iii,14(3), iii,15(6), iii,16*(5), iv,13(1), iv,14(3), iv,15(7), iv,16(4), iv,17(2), v,13(1), v,14(3), v,15(5), v,16(3), v,17(2).Anal-fin pterigiophores 17(2) or 18(1). Anal-fin rays of mature males bearing one or two retrorse bony hooks along posterolateral border of each segment of lepidotrichia, usually along last unbranched ray to fifteen anterior branched rays. Anal-fin hooks more numerous along first to tenth branched rays and usually located along posterior most branch and distal one-half to two-thirds of length of each ray. Some mature females bearing few bony hooks on last unbranched ray and anterior branched anal-fin rays. Anal-fin origin located posterior to vertical through base of last dorsal-fin ray. Distal margin of anal fin concave in females, nearly straight in males. Caudal fin forked, lobes approximately similar in size, slightly pointed, with i,16,i(5) or i,17,i*(35) rays. Dorsal procurrent caudal-fin rays 10(2), 11(6) or 12(3). Ventral procurrent caudal-fin rays 9(2) or 10(10).

Scales cycloid, moderately large. Lateral line complete, with 35(1), 36(7), 37*(16), or 38 (16) perforated scales. Scale series between dorsal-fin origin and lateral line 5(1), 6*(40) or 7(1). Scale series between lateral line and pelvic-fin insertion 5*(42). Predorsal scales 12(1), 13*(14), 14(18) or 15(6) and regularly arranged. Circumpeduncular scales 13(11), 14*(25) or 15(5). Scale sheath along anal-fin base formed by five to seven scales in single series covering base of anterior most rays.

Total vertebrae 34(3), 35(1), 36(6) or 37(2), precaudal vertebrae 17(1), 18(8) or 19(3), caudal vertebrae 17(5), 18(5) or 19(1). Ribs 13(3). Supraneurals 4(5), 5(5) or 6(2).

Color in alcohol. Dorsal portion of head and body densely dark brown; dorsolateral portions of head and body brownish and lighter ventrally. Body with broad, blackish midlateral band from humeral region to caudal peduncle. Midlateral band expanded dorsally and ventrally into a dark lozenge shaped spot on caudal peduncle. Single, brown, narrow, sometimes inconspicuous vertically elongate humeral spot. Dorsal portion of spot slightly wider than ventral. Ventral limit of spot over first to second scale below lateral line and dorsal limit about two to three horizontal series of scales above lateral line. Fins with scattered dark chromatophores, mainly over distal third; pigmentation more obvious on median fins. Caudal fin with a faint dark pigmentation on middle rays.

Sexual dimorphism. Males of Astyanax jordanensis   posses bony hooks on the dorsal-, pectoral-, pelvic-, and anal-fin rays, albeit with hooks less evident on the dorsal fin. Males and females also slightly differ in the proportions of the dorsal, pectoral, and pelvic fins ( Table 1) and in the anal-fin shape, which is concave in females and nearly straight in males ( Fig. 1). Mature females reach larger body sizes than mature males (44.3-75.7 mm vs. 34.2-47.7 mm SL, respectively).Twenty one mature female paratypes have a few small bony hooks on the last unbranched ray and anterior branched anal-fin rays, a character unusual in characids (see discussion for more details). Gill glands were not found in either males or females.

Distribution. All specimens were collected in the middle and upper portions of rio Jacu and rio das Torres in the lower portions of the rio Jordão drainage, lower rio Iguaçu basin, Paraná, Brazil ( Fig. 3).

Etymology. The specific name jordanensis   is in reference to the drainage from where the species is described, the rio Jordão, a tributary to the rio Iguaçu basin. An adjective.

Ecological notes. Stomach contents of four paratypes included aquatic insects (Epemeroptera; Hemiptera   : an adult of Gerridae   ; Diptera   : pupa, and larvae of Ceratopogonidae   ), terrestrial insects (adults of Diptera   ; Hymenoptera; Lepidoptera; and Coleoptera), and plant fragments (fruits of Gramineae; sporophytes and leaves of the Bryophyta).

MCP

Pontificia Universidade Catolica do Rio Grande do Sul