Astyanax joaovitori, Bertaco, Vinícius Araújo, 2017

Bertaco, Vinícius Araújo, 2017, A new species of Astyanax Baird & Girard (Characiformes: Characidae) from the upper rio Araguaia, Central Brazil, Zootaxa 4320 (1), pp. 173-182 : 174-178

Astyanax joaovitori , new species

( Figs. 1–2 ; Table 1)

Astyanax sp. 1.— Benedito-Cecílio et al., 2004: 375 –376 (listed, frequency of distribution; Brazil, Goiás, Emas National Park, Rio Paranaíba basin).

Astyanax sp. 3.— Benedito-Cecílio et al., 2004: 375 (in part; Brazil, Goiás, Emas National Park, Rio Paranaíba basin).

Holotype. MCP 51897, 44.9 mm SL, Brazil, Mato Grosso State, municipality of Alto Taquari, headwaters of rio Araguaia , near Parque Nacional das Emas, 17°53’52”S 53°07’38”W, 22–26 Sep 1999, C.H. Zawadzki, E. Benedito-Cecílio & C.V. Minte-Vera.

Paratypes. [210 specimens, 19.9–77.0 mm SL, (104 specimens measured/counted, 28.5–77.0 mm SL, 6 r, 40.5–60.4 mm SL, 4 c&s, 25.4–29.5 mm SL) plus 106 specimens not-measured/counted, 19.9–75.3 mm SL]. All from Brazil, Mato Grosso State, upper rio Araguaia drainage. MZUEL 18117, 19, 34.1–60.4 mm SL, 6 r, 40.5–60.4 mm SL; NUP 833, 14, 29.3–35.2 mm SL; NUP 1945, 28, 29.4–57.8 mm SL; NUP 9559, 4 c&s, 25.4–29.5 mm SL, collected with holotype . LIRP 4503, 29, 20.1–44.7 mm SL, municipality of Alto Araguaia, Córrego do Sapo, tributary of rio Araguaia , 17°31’11”S 53°15’33”W, 7 Aug 2002, A.L.A. Melo & L.S.F. Martins . MCP 51898, 32, 31.2–44.8 mm SL; NUP 2320, 59, 19.9–31.9 mm SL, municipality of Alto Taquari, rio Araguaia, near Parque Nacional das Emas , 17°41’29”S 53°14’13”W, 1 Dec 1999, C.H. Zawadzki, E. Benedito-Cecílio & C.V. Minte- Vera . NUP 14857, 25 , 52.3 –77.0 mm SL, municipality of Alto Taquari, headwaters of rio Araguaia , near Parque Nacional das Emas, 17°41’29”S 53°14”13”W, 8 Dec 1999, C.H. Zawadzki, E. Benedito-Cecílio & C.V. Minte- Vera.

Diagnosis. Astyanax joaovitori is a member of Astyanax scabripinnis species complex sensu Bertaco & Lucena (2006) and Ingenito & Duboc (2014). The new species differs from A. burgerai Zanata & Camelier , A. epiagos Zanata & Camelier , A. eremus Ingenito & Duboc, A. goyanensis (Miranda-Ribeiro) , A. guaricana Oliveira, Abilhoa & Pavanelli , A. gymnogenys Eigenmann, A. intermedius Eigenmann , A. ita Almirón, Azpelicueta & Casciotta , A. jacobinae Zanata & Camelier , A. jenynsii (Steindachner) , A. laticeps (Cope) , A. leonidas Azpelicueta, Casciotta & Almirón , A. microschemos Bertaco & Lucena , A. obscurus (Hensel) , A. ojiara Azpelicueta & Garcia, A. paranae Eigenmann , A. paris Azpelicueta, Almirón & Casciotta , A. pirabitira Lucena, Bertaco & Barbigier , A. pirapuan Tagliacollo, Britzke, Silva & Benine , A. rivularis (Lütken) , A. serratus Garavello & Sampaio , A. troya Azpelicueta, Casciotta & Almirón , A. turmalinensis Triques, Vono & Caiafa , and A. varzeae Abilhoa & Duboc by presenting the dark midlateral stripe beginning immediately behind the upper margin of the opercle (vs. beginning after first humeral blotch; A. epiagos and A. jacobinae lack the dark midlateral stripe). Astyanax brachypterygium Bertaco & Malabarba , A. courensis Bertaco, Carvalho & Jerep , A. cremnobates Bertaco & Malabarba , A. jordanensis Alcaraz, Pavanelli & Bertaco , and A. totae Haluch & Abilhoa present region immediately posterior to the humeral spot pale in some specimens, but this region is never pale in the new species. Astyanax joaovitori differs from A. brachypterygium and A. cremnobates by presenting the postero-ventral margin of third infraorbital close to the margin of preopercle, leaving a narrow naked area between these bones less than 25% of the depth of third infraorbital (vs. margin of third infraorbital distant from the margin of preopercle, leaving a broad area, more than 25% of the depth of third infraorbital). Astyanax joaovitori differs from A. courensis by the presence of a pattern of scattered chromatophores at abdominal region (vs. scales at abdominal region presenting reticulate color pattern). Astyanax joaovitori can be distinguished from A. jordanensis by the absence of bony hooks on dorsal fin in males (vs. presence) and from A. totae by presenting 13 or 14 circumpeduncular scales (vs. 15 to 19). It is impossible to infer about the midlateral stripe of the holotype of A. scabripinnis due to the loss of coloration, however A. joaovitori differs from A. scabripinnis by having 33–36 lateral line scales (vs. 38).

Description. Morphometric data presented in Table 1. Maximum size 77.0 mm SL. Body elongated and compressed, deepest and heaviest in area proximate at middle of pectoral fins. Dorsal profile straight or slightly convex between vertical posterior to nostrils and supra-occipital process, convex from this point to end of dorsal fin, and slightly convex or straight between dorsal and adipose fins. Ventral profile convex between tip of snout and origin of pelvic fin, straight between pelvic and anal fins, straight along base of anal fin. Caudal peduncle with dorsal and ventral margin straight or slightly concave.

Snout rounded from upper lip to vertical through anterior nares. Head relatively small. Mouth terminal. Maxillary bone extending beyond vertical through anterior margin of orbit, slightly curved and forming an angle of approximately 45° relative to longitudinal axis of body. Postero-ventral margin of third infra-orbital close to preopercle, leaving a small naked area between edge of these bones less than 25% of depth of third infraorbital.

Premaxilla with two teeth rows, outer row with 3(3), 4*(91) or 5(7) teeth with three to five cusps. Inner row with five teeth gradually decreasing in size from first towards fourth tooth, with last tooth distinctly smaller. Teeth of symphysis asymmetric with four to six cusps, typically five, second and third teeth large, with seven to nine cusps, fourth and fifth teeth with five to seven cusps. Maxilla with 0(2), 1*(93), or 2(6) teeth, with three to five cusps, commonly five, and second tooth, when present, with three cusps. Dentary bone with four*(63), or five (6) larger anterior teeth, followed by six to nine smaller teeth; teeth at symphysis with five or seven cusps, remaining larger teeth with 4-7 cusps; smaller teeth with three cusps or conical. Size of dentary teeth changing abruptly from fourth to fifth or fifth to sixth tooth. All teeth with central cusp greater than remaining ones. Dorsal-fin rays ii(10) + 8(2) or 9*(99) rays [mean = 9]. First unbranched ray with about half the length of second ray. Distal margin of dorsal fin straight, its origin anterior to first half of standard length. Adipose fin at vertical through last anal-fin rays. Anal-fin rays iv(6) or v(4) + 15(1), 16(28), 17(39), 18*(25), 19(3), or 20(1) [mean = 17]. Distal border of anal fin smoothly concave. Origin of anal fin immediately posterior to vertical through origin of last dorsal-fin ray. Pectoral-fin rays i(10), 10(12), 11*(45), 12(39), or 13(5) [mean = 11], its origin anterior to posterior margin of opercle; when adpressed not reaching origin of pelvic fin in specimens larger than 50.0 mm SL. Pelvic-fin rays i(10), 6(5), or 7*(96) [mean = 7], its origin anterior to vertical through dorsal-fin origin; when adpressed not reaching origin of anal fin.

Caudal fin forked, with lobes similar in length, with i+17+i (n=101) principal rays. Dorsal procurrent rays 9(1), 10(2), 11(3) or 12(2) and ventral procurrent rays 7(1), 8(5), 9(1), 10(1) or 11(1).

Scales cycloid, moderately large. Lateral line complete, with 33(6), 34(26), 35*(39), or 36(24) [mean = 35] perforated scales. Series of scales above lateral line 5(2), 6*(85), or 7(8) [mean = 6]; below 5*(82), or 6(16) [mean=5]. Pre-dorsal scales 10(30), 11(35), 12*(23), or 13(6) [mean = 11]. Circumpeduncular scales 13(3), or 14*(70) [mean = 14]. Single row of scales covering base of anal fin with 3(5), 4(7), 5(30), 6(22), or 7(11) [mean = 5] scales.

Supraneurals 4(1), 5(8), or 6(1). Precaudal vertebrae 16(4), or 17(6), caudal 16(3), or 17(7), total vertebrae 33(7), or 34(3). Tip of first dorsal-fin pterygiophore behind neural spine of 9th(2), 10th(7), or 11th(1) vertebrae and tip of last dorsal-fin pterygiophore before neural spine of 16th(1), 17th(8), or 18th(1) vertebrae. Tip of first anal-fin pterygiophore behind hemal spine of 17th(9), or 18th(1) vertebrae and tip of last anal-fin pterygiophore before hemal spine of 25th(4), 26th(5), or 27th(1) vertebrae. First gill arch with 6*(41), 7(43), or 8(3) upper gill rakers, one at the angle between upper and lower arches, and 8*(3), 9(30), 10(52), or 11(3) lower gill rakers [mean = 7+i+10].

Color in alcohol. Overall body color beige. Dorsal and dorsolateral region of head and trunk light brown. Dark chromatophores scattered on lateral portion of head, more densely concentrated on snout and anterior border of eye. Broad, dark midlateral stripe extending from immediately behind upper margin of the opercle to caudal-fin base, deeper on caudal peduncle, and continuous after humeral blotch. Dark pigmentation present on middle caudal-fin rays. A single, relatively diffuse dark humeral blotch, vertically elongate, with dorsal portion wider, sometimes inconspicuous, extending over two horizontal series of scales above lateral line; ventral portion of blotch narrower, extending over one to two horizontal series of scales below lateral line. Scattered dark chromatophores widespread at abdominal region. Fins with few, scattered dark chromatophores.

Sexual dimorphism. Hooks on the anal fin present only in mature males, from the last unbranched ray to the 8th branched ray. Pectoral fin with hooks from 1st to 8th unbranched rays. All specimens with hooks on anal fin also presented hooks on pectoral fin. Pelvic fin usually without hooks, a single specimen, NUP 1945, 34.4 mm SL, with hooks on 2nd and 3rd unbranched rays.

Distribution. Astyanax joaovitori is known only from the upper rio Araguaia and some tributaries, Mato Grosso State, Brazil ( Fig. 2 ).

Etymology. Astyanax joaovitori is named after João Vitor Kadota Oliveira, son of the first author. A genitive.

Figures

FIGURE 1. (a) Astyanax joaovitori, holotype, female, MCP 51897, 44.9 mm SL, Brazil, Mato Grosso, municipality of Alto Taquari, headwaters of rio Araguaia. (b) Astyanax joaovitori, paratype, female, MZUEL 18117, 41.8 mm SL, same data as holotype. (c) Astyanax joaovitori, paratype, female, LIRP 4503, 39.0 mm SL, Brazil, Mato Grosso, municipality of Alto Araguaia, córrego do Sapo. Lateral view of abdominal region showing scattered pattern of dark chromatophores. (d) Astyanax courensis, paratype, undetermined sex, UFRGS 11290, 43.7 mm SL, Brazil, Goiás, municipality of Alto Paraíso de Goiás, rio dos Couros. Lateral view of abdominal region showing reticulate pattern of chromatophores.

FIGURE 2. Map of southwestern Brazil, showing the geographic distribution of Astyanax joaovitori. Red star indicates the type-locality, yellow dots remaining known localities for the species. Green square represents Cachoeira Couto Magalhães (see text).