Astyanax pirapuan, Tagliacollo, Victor A., Britzke, Ricardo, Silva, Gabriel S. C. & Benine, Ricardo C., 2011

Tagliacollo, Victor A., Britzke, Ricardo, Silva, Gabriel S. C. & Benine, Ricardo C., 2011, Astyanax pirapuan: a new characid species from the upper Rio Paraguay system, Mato Grosso, Central Brazil (Characiformes, Characidae), Zootaxa 2749, pp. 40-46 : 41-44

Astyanax pirapuan , new species

( Fig. 1 ; Table 1 )

Holotype. MNRJ 37621, undetermined sex, 45.4 mm SL, Brazil: Chapada dos Guimarães, Mato Grosso State, Rio Aricá-Mirim, Rio Cuiabá basin, 15°46’04”S 55°30’44”W, 25 Nov 2005, N. G. Machado & W. R. C. Assunção.

Paratypes. Brazil, Chapada dos Guimarães, Mato Grosso state: MNRJ 29315, 25, 27.6–65.2 mm SL, Rio Aricá-Mirim, Rio Cuiabá basin, 15°43’11”S 55°27’18”W, 25 Nov. 2005, N. G. Machado & W. R. C. Assunção. MNRJ 29357, 4, 35.6–51.0 mm SL, small stream of Rio Aricá-Mirim, Rio Cuiabá basin, 15°47’28”S 55°29’46”W, 27 Nov 2005, F. Modesto & A. Fiorentino. MNRJ 37622, 9, 24.4– 55.7 mm SL, same data as holotype. LBP 5662, 10, (2 c&s), 29.9–57.3 mm SL, Santo Antônio de Leverger, Rio Aricá-Mirim, 15°46’04”S 55°30’44”W, 0 7 august 2007, M. N. Mehanna & A. Ferreira.

Non-type material (unadequated fixed material). LBP 5067, 2, 29.9–36.7 mm SL, LBP 5668, 5, 48.5–58.2 mm SL, Brazil, Mato Grosso State, Santo Antônio de Leverger, Rio Aricá-Mirim, 15°46’04”S 55°30’44”W, 0 8 august 2007, M. N. Mehanna & A. Ferreira.

Diagnosis. Astyanax pirapuan belongs to the A. scabripinnis species complex and is distinguished from all species of this complex by the combination of the following characters: number of branched anal-fin rays (17–21 vs. 13–17 in A. jenynsii and A. brachypterygium ; 13–16 in Astyanax goyanensis ; 13–17 in A. jordanensis ; 15–17 in A. cremnobates , A. microschemos and A. courensis ); teeth on maxilla (0–1 tricuspidate tooth vs. 1 heptacuspidate in A. ojiara ; 2 in A. intermedius ; 2–5, usually, 3 in A. leonidas and A. totae ; 3–4 in A. paris ); scale perforated (35– 37, usually 36 vs. 31–34 in A. burgerai ; 38–40 in A. paranae ; 37–39 in Astyanax obscurus ); humeral spots (two vs. one in A. ita and A. rivularis ); number of gill rakers on the upper limb of first branchial arch (8–9 vs. 6–7 in A. laticeps ; 7 in A. varzeae ). Yet, it is distinguished from A. troya through bony hooks (only on anal-fin vs. on pectoral, pelvic, anal and caudal fins in A. troya ); from A. scabripinnis by number of circumpeduncular scales (12–14 vs. 16 in A. scabripinnis ); from A. turmalinensis by series of scales between lateral line and pelvic-fin origin (4–5 vs. 5–6, usually 5, in A. turmalinensis ), and number of teeth (0–1 tricuspidate tooth vs 1–2 tri-pentacuspidate teeth, usually 2, in A. turmalinensis ).

Description. Morphometric data of holotype and paratypes are summarized in Table 1 . Elongate and moderately compressed body. Greatest body depth usually immediately anterior to dorsal-fin origin. Dorsal profile of head between vertical through posterior nostril and tip of supraoccipital spine straight or slightly convex. Profile of body convex from tip of supraocciptal spine to base of last dorsal-fin ray, and slightly concave from that point to adipose-fin origin. Ventral profile of head convex. Ventral profile of body slightly convex from pectoral-fin insertion to anal-fin origin. Body profile along anal-fin base posterodorsally inclined. Caudal peduncle with dorsal and ventral profiles nearly straight. Snout rounded from margin of upper lip to vertical through anterior nostrils. Head relatively small. Mouth terminal. Upper jaw slightly longer than or equal to lower jaw. Maxilla short, not extending up to vertical through half of orbit, and aligned at angle of approximately 45 degrees relative to longitudinal body axis.

Premaxilla with two tooth rows. Outer row with 3 (2), 4* (29) or 5 (9) tricuspid teeth with central cusp slightly longer. Inner row teeth 4 (6), 5* (32) or 6 (1) three-pentacusp teeth with central cusp twice longer and broader than other cusps. Maxilla with 1* (35) or 0 (3), tricuspid teeth. Dentary with 4* (44) anteriormost pentacuspidate larger teeth, followed by 5 (2) smaller tricuspid or conical teeth which are gradually decreasing in size; central cusp in all teeth are always larger than lateral ones and slightly reclined back ( Fig. 2 ). Dorsal-fin rays ii (40), 8 (1), 9* (39). First unbranched ray smaller than second one. Dorsal-fin origin posterior to middle body; distal border smoothly rounded. Dorsal-fin pterygiophores 10 (2). Anal-fin rays iii, 18 (5), 19 (3), 20 (1), iv-17 (1) 18 (3), 19* (15), 20 (11), or 21 (1). Anal-fin origin situated posterior to vertical through base of last dorsal-fin ray. Pelvic-fin rays i, 7* (40). Pelvic-fin origin anterior to vertical line through dorsal-fin origin; distal border slightly convex tip not reaching anal-fin origin. Pectoral-fin i, 8 (1), 9 (7), 10 (11), 11 (12), or 12* (9). Caudal fin forked and unscaled, lobes similar in size, with 19 principal rays (2). Dorsal procurrent rays 8 (2) and ventral procurrent rays 10 (2). Lateral line complete. Perforated scales in longitudinal series 35 (16), 36* (20) or 37 (10). Scale rows between dorsal-fin origin and lateral line 6* (49); scale rows between lateral line and pelvic-fin origin 4 (38) or 5* (9). Scale rows around caudal peduncle 12 (7), 13* (35) or 14 (5). Predorsal scales 40* (11). Presence of the sheath scale of analfin base and axillary scale on pelvic fin origin. Precaudal vertebrae 17(2); caudal vertebrae 18 (1) or 19 (1). Supraneural 5 (2). Gill-rakers 11/8 (21), 12/8* (18), or 12/9 (1).

5662) of Astyanax pirapuan . SD = Standard deviation. N = 49.

Color in alcohol. Overall ground color pale yellow, darker dorsally and yellowish ventrally. Dark chromatophores densely concentrated on dorsal surface of head from upper lip to supraoccipital spine. Dark chromatophores sparsely distributed over infraorbitals and two anterior thirds of maxilla. Opercle with sparse and large dark chromatophores. Ventral portion of head less pigmented, with scattered dark chromatophores more concentrated on anteromedian area. Dark chromatophores concentrated on distal margin of scales resulting in conspicuous reticulated pattern. Mid-dorsal region darker than flanks. Body with black, pigmented, midlateral stripe extending from second humeral mark to base of middle caudal fin, usually wider and more densely pigmented on caudal forming small caudal spot. Humeral region with two vertically-elongated spots. Anterior spot conspicuous, vertically elongated with upper portion broader and more evident than lower portion. Posterior humeral spot diffuse, with variable shape rounded, not ventrally surpassing lateral-line. Region between spots pale. Fins with dark chromatophores forming lines along rays extension; small chromatophores homogeneously distributed over membranes and borders of rays. Adipose fin with scattered small dark chromatophores.

Sexual dimorphism. Males of Astyanax pirapuan are promptly recognized by the presence of a pair of bony hooks on the distal segments of the last unbranched and and the first eight branched anal fin ray. The bony hooks are aproximately the same size. No other secondary sexually dimorphic feature was identified.

Etymology. The specific name pirapuan , from Tupi-Guarani, meaning “mountain fish” (pira = fish; apu = mountain) is an allusion to the geological characteristics of the type locality, Chapada dos Guimarães, Mato Grosso State, Brazil.

Distribution. Astyanax pirapuan is known from tributaries of Rio Aricá-Mirim, Rio Cuiabá basin, Chapada dos Guimarães, Mato Grosso State, Brazil ( Fig. 3 ).

Remarks. Astyanax pirapuan represents the first report of A. scabripinnis species complex in the Rio Paraguay basin. Recent description have demonstrated that species of this complex have restricted geographical distributions (e.g. Astyanax brachypterygium ; A. cremnobates ; A. ita ; A. ojiara ; A. paris ; A. totae ; A. troya ; A. turmalinensis ; A. goyanensis ; A. courensis ), which also seems to occur with A. pirapuan , as we have been collecting in many river basins and it has not been reported in other regions.

Six species of Astyanax are known from the Rio Paraguay basin: A. abramis , A. asuncionensis , A. lineatus , A. marionae , A. paraguayensis and A. pellegrini . These species are distinguished from A. pirapuan since they do not present the diagnostic features of the Astyanax scabripinnis species complex sensu Bertaco & Lucena (2006). Besides, Astyanax pirapuan can be easily distinguished from A. asuncionensis , A. abramis and A. paraguayensis by the absence of a conspicuous oval-shaped spot in humeral area (vs. presence of an oval-shaped spot in the humeral area). Yet, it can be distinguished from A. lineatus , A. marionae and A. pellegrini by the number of anal fin-rays (21–24 vs. 26–28; 27– 29 and 41–45, respectively).

Comparative material. Astyanax abramis : LBP 8422, 5, 39.17–53.11 mm, tributary of Rio Sepotuba, Tangará da Serra, Rio Paraguay basin, Mato Grosso State. Astyanax assuncionensis : LBP 8427, 10, 27.86–36.98 mm SL, Rio Sepotuba, Rio Paraguay basin, Tangará da Serra, Mato Grosso State. Astyanax biotae : MZUEL 4529, 1, 53.47 mm SL, stream Água Mole, Rio Paranapanema basin, Diamante do Norte, Paraná State. Astyanax brachypterygium : MZUSP 62713, paratypes, 10, 37.2–59.5 mm SL, arroio Água Branca, Rio Uruguay basin, Bom Jesus, Rio Grande do Sul State. Astyanax burgerai : MZUSP 101245, holotype, 1, 53.2 mm SL, córrego Água Boa on road between Floresta Azul and Almadina, tributary of small stream Pancadinha, itself a tributary of Rio Almada, Almadina, Bahia State. Astyanax cremnobates : MZUSP 62712, paratypes, 10, 37.5–64.9 mm SL, tributary of Rio Santa Cruz, Rio Jacu basin, São Francisco de Paula, Rio Grande do Sul State. Astyanax intermedius : MZUSP 47745, 1, 106.3 mm SL, tributary of Pedra Branca, Rio Paraíba do Sul basin, Cunha, São Paulo State. Astyanax jordanensis : MZUSP 99138, paratypes, 8, 42.7–76.1 mm SL, middle Rio Jacu, Rio Iguaçu basin, Candói, Paraná State. Astyanax lineatus : LBP 7636, 2, 38.09–43.39, mm SL, Rio Coxipó-Açu, Rio Paraguay basin, Chapada dos Guimarães, Mato Grosso State. Astyanax marionae : LBP 5830, 1, 50.37 mm, Rio Coxipó-Açu, Rio Paraguay basin, Cuiabá, Mato Grosso State. Astyanax paranae : CAS 22555, 1, holotype (photograph), Paraná State; MHNCI 8138, 10, 48.45–86.55 mm SL, Rio Lageado do Pitó, Rio Tibagi basin, Palmeira, Paraná State; MZUEL 1601, 3, 41.39–57.89 mm SL, tributary of Rio Lapé, Rio Tibagi basin, Fazenda das Rosas, Castro, Paraná State; MZUSP 55000, 6, 36.1– 54.1 mm SL, creek tributary of Rio Tibagi, upper Paraná basin, Fazenda das Rosas, Castro, Paraná State. Astyanax rivularis : MZUSP 39724, 20, 49.3–77.8 mm SL, córrego Guará, Rio São Francisco basin, Três Marias, Minas Gerais State. Astyanax aff. rivularis : MZUEL 5011, 3, 69.91–87.77 mm SL, Rio das Velhas, Rio São Francisco basin, São Bartolomeu, Minas Gerais State. Astyanax totae : MNRJ 28652, 10, 36.9–66.3 mm SL, Rio Cascata, tributary of Rio Tortuoso, Rio Iguaçu basin, Balsa Nova, Paraná State; MHNCI 10338, 15, 32.3–71.3 mm SL, Rio Cascata, tributary of Rio Tortuoso, Rio Iguaçu basin, Balsa Nova, Paraná State. Astyanax varzeae : MHNCI 11688, 1, 83.1 mm SL, Rio São João, Rio da Várzea headwaters, a tributary of Rio Negro, Rio Iguaçu basin, Tijucas do Sul, Paraná State. Astyanax xavante : MZUSP 100376, paratypes, 15, 18.8–59.6 mm SL, creek tributary to the córrego Avoadeira, inside the Parque Estadual da Serra Azul, Barra do Garças, Mato Grosso State.

Figures

FIGURE 1. Astyanax pirapuan, holotype, undetermined sex, MNRJ 37621, 45.4 mm SL, Brazil, Mato Grosso, Chapada dos Guimarães, Rio Aricá-Mirim, Rio Cuiabá basin.

FIGURE 2. Astyanax pirapuan, paratype, LBP 5662, 54.3 mm SL. Upper and lower jaws, left lateral view. Scale bar = 1 mm.

FIGURE 3. Area showing sites of occurrence of Astyanax pirapuran (Brazil, Mato Grosso State, Chapada dos Guimarães, Rio Aricá-mirim, Rio Cuiabá basin, 1543 ’ 11 ” S 5527 ’ 18 ” W). Star: type locality, white circle: paratypes, square: Cuiabá, MT.

Tables

TABLE 1. Morphometrics data of holotype (MNRJ 37621) and paratypes (MNRJ 29315; MNRJ 29357; MNRJ 37622 LBP

	Holotype Paratypes Range	Mean	SD
Standard length (mm) Percents of standard length Greatest depth Snout to dorsal-fin origin Snout to pectoral-fin origin Snout to pelvic-fin origin	45.4 22.0–65.2 32.1 30.7–37.4 52.8 51.2–56.7 28.5 26.3–31.5 49.8 48.0–53.3	41.3 34.3 53.9 28.8 50.2	- 1.7 1.3 1.2 1.4
Snout to anal-fin origin Caudal peduncle depth Caudal peduncle length Pectoral-fin length	69.2 64.8–69.9 11.8 10.9–12.5 11.1 9.3–13.2 21.5 17.9–21.7	67.3 11.9 11.4 20.2	1.4 0.4 0.9 0.8
Pelvic-fin length Dorsal-fin length	16.4 14.4–17.6 22.6 21.7–27.1	16.1 24.2	0.8 1.5
Dorsal-fin base length Anal-fin length Anal-fin base length Eye to dorsal-fin origin Dorsal-fin origin to caudal-fin origin Head length	12.8 11.8–14.3 18.5 16.3–20.4 23.3 21.1–25.3 40.4 37.8–42.8 50.6 48.4–53.4 27.8 27.0–30.5	13.1 18.3 23.6 39.9 50.4 28.4	0.7 1.1 0.9 1.1 1.2 0.8
Head depth Percents of head length Snout length Upper jaw length Horizontal orbital diameter Least interorbital width	19.8 19.2–23.0 23.7 18.8–24.9 28.0 24.5–30.3 31.4 30.9–37.3 34.5 31.7–39.2	21.2 22.0 27.4 34.2 35.6	1.1 1.6 1.7 1.8 1.5