Leporinus santosi, Britski & Birindelli, 2013

Britski, Heraldo A. & Birindelli, José L. O., 2013, A new species of Leporinus Agassiz, 1829 (Characiformes: Anostomidae) from the rio Tocantins, Brazil, Neotropical Ichthyology 11 (1), pp. 25-32 : 26-28

Leporinus santosi , new species

Fig. 1

Leporinus granti .- Santos & Jégu, 1989: 159, 170, 171, 179, 190, figure 14, plate 3, figure 8 [lower rio Tocantins].

Holotype. MZUSP 110000, 117.5 mm SL, Brazil, Pará , Parauapebas , igarapé do Pojuca , tributary of rio Itacaiúnas, at Caldeirão, approximately 5°52’S 50°32’W, 15 Oct 1983, M. Goulding.

Paratypes. All from Brazil, Pará . ANSP 192959 , 1 , 96.8 mm SL ; INPA 37891 , 1, 117.8 mm SL ; MZUSP 31482 , 1, 121.5 mm SL ; MZUSP 32307 , 5 , 89.4 -155.0 mm SL, 1 CS, 112.1 mm SL; collected with the holotype . INPA 1589 , 2 , 41.1 and 68.9 mm SL, Marabá, igarapé Pucuruizinho , tributary of rio Tocantins, 26 Nov 1981, G. M. Santos . MZUSP 29156 , 11 , 62.2-78.9 mm SL, Parauapebas, rio Itacaiúnas at cachoeira Carreira Comprida , Caldeirão , approximately 5°52’S 50°32’W, 14 Oct 1983, M. Goulding . MZUSP 42021 , 4 , 111.5 -135.0 mm SL, igarapé do Onze, at km 11 on road Tucuruí- Mato Grosso, 3°51’11”S 49°40’55”W, 22 Sep 1970, Expedição Permanente da Amazônia .

Diagnosis. Leporinus santosi is distinguished from all congeners, except for L. gomesi , L. granti , and L. nijsseni , for having three prominent dark midlateral blotches, smaller blotches formed by dermal pigment, five of which form an interrupted “X” between head and first midlateral blotch, small dark spots formed by epidermal pigment, terminal mouth with four teeth on premaxilla and four on dentary, and relatively few scales on lateral line (less than 36). Leporinus santosi is further distinguished from all congeners, except L. gomesi , by having a conspicuous dark spots on the center of scales on anterolateral portion of the body ( Figs. 1a, b and 5a ). Leporinus santosi is distinguished from L. gomesi by having 16 (vs. 12) scale rows around the caudal peduncle, and the second midlateral dark blotch rounded and not extended posteriorly to the vertical through the posterior margin of the adipose fin (vs. second midlateral dark blotch elongate, extended posteriorly to the vertical through the posterior margin of the adipose fin).

Description. Morphometric data in Table 1. Middle-sized, when compared to congeners; largest examined specimen 155.0 mm SL (MZUSP 32307). Head and body moderately compressed and relatively deep. Dorsal profile convex from snout tip to dorsal-fin origin, somewhat straight along dorsal-fin base, straight and descending slightly from dorsal-fin end to adipose-fin origin, and usually concave from adipose-fin origin to anteriormost procurrent ray of caudal fin. Ventral profile convex from lower jaw to pelvic-fin origin, straight from latter point to anal-fin origin, convex along anal-fin base, and concave from anal-fin end to anteriormost procurrent ray of caudal fin. Greatest body depth at or slightly anterior to dorsal-fin origin.

Mouth terminal, its cleft longitudinally aligned with middle of orbit in specimens up to approximately 60 mm SL, or to ventral margin of eye in larger specimens. Snout rounded, anteriorly blunt. Premaxilla with four (24) incisiform teeth gradually decreasing in size from symphyseal tooth. Dentary with four (24) incisiform teeth also gradually decreasing in size posterolaterally ( Fig. 2 ).

Scales cycloid, with 5 (1) or 7 (2) radii. Lateral line complete with 33 (3) or 34* (19) perforated scales, extending from supracleithrum to base of median caudal-fin rays. Longitudinal scale rows between dorsal-fin origin and lateral line 4 (24). Longitudinal scale rows between lateral line and pelvic-fin origin 4 (24). Longitudinal scale rows around caudal peduncle 16 (24). Predorsal scales from tip of supraoccipital spine to dorsal-fin origin 9* (3), 10 (18), or 11 (3).

Dorsal fin ii,10 (24) rays; its origin slightly anterior to middle of standard length and to vertical through pelvic-fin origin; distal margin gently convex.Adipose fin small, teardrop shaped, its origin approximately at vertical through base of last anal-fin ray. Pectoral fin i,12 (7); i,13* (15) or i,14 (2); its tip extending slightly beyond half distance between origins of pectoral and pelvic fin; distal margin rounded. Pelvic fin i,8 (24); distal margin slightly convex.Anal fin ii,8 (24); its origin approximately at vertical through third scale anterior to adipose-fin origin, when adpressed fin almost reaching base of caudal-fin rays; distal margin straight or gently concave. Principal caudal-fin rays i,8,9,i (24). Caudal fin forked, lobes rounded, upper lobe slightly longer than lower lobe. Vertebrae 33 (1), with ribs on vertebrae five through 19.

Coloration. Ground color of head and body light brown, weakly countershaded. Head with one dark oblique stripe from top of snout, through eye, to posteriormost margin of opercle; one dark oblique stripe (sometimes faded) from upper lip, through ventral margin of eye, to ventral corner of preopercle; one dark spot between infraorbital 6 and dorsal margin of opercle. Body with three prominent dark round midlateral blotches (surrounding pale area), first one centered on vertical through base of last rays of dorsal fin, second one centered on vertical through base of anterior anal-fin rays, and third one on posterior half of caudal peduncle. Midlateral blotches decreasing in size posteriorly. Midlateral blotches formed by both dermal and epidermal pigments. Body with many smaller dark round blotches formed by dermal pigment, including five blotches forming interrupted “X” between head and first midlateral blotch. In addition, center of each scale of anterolateral portion of body, between opercle and terminus of first midlateral blotch, with conspicuous dark spot formed by epidermal pigment; dark spots arranged in about eight longitudinal rows. Ventral surfaces of head and belly pale to cream. All fins predominantly hyaline.

Geographic distribution. Leporinus santosi is known from a tributary of the rio Tocantins, at the stretch now inundated by the Tucuruí reservoir, and a tributary of the rio Itacaiúnas, a large tributary of the lower rio Tocantins ( Fig. 3 ).

Etymology. Named in honor of Geraldo Mendes dos Santos, a researcher from INPA, for his important contributions to our knowledge of the fish fauna of the lower rio Tocantins, through his studies on the species of Anostomidae ( Santos & Jégu, 1989) , and on the impacts of the Tucuruí dam ( Santos et al., 1984; Santos et al., 2004). An noun.

Figures

Fig. 1. Leporinus santosi: (a) holotype, MZUSP 110000, 117.5 mm SL, igarapé do Pojuca, tributary of rio Itacaiúnas, 5°22’S 50°32’W, Parauapebas, Pará, Brazil; (b) paratype, 29156, 61.6 mm SL, rio Itacaiúnas at cachoeira Carreira Comprida, 5°52’S 50°32’W, Parauapebas, Pará, Brazil.

Fig. 5. Leporinus gomesi (a), MZUSP 14441, paratype, 104.3 mm SL, igarapé da Chapada, tributary of igarapé do Aeroporto, rio Aripuanã drainage,Aripuanã, Mato Grosso, Brazil; Leporinus nijsseni (b), MZUSP 48506, 138.5 mm SL, Sara creek, Brokopodo, Suriname.

Fig. 2. Upper and lower jaws of Leporinus santosi, MZUSP 32307, 121.1 mm SL, in lateral view.

Fig. 3. Distribution of Leporinus santosi. White symbol represents the type locality.