Leporinus guttatus, Birindelli & Britski, 2009

Birindelli, José L. O. & Britski, Heraldo A., 2009, New species of the genus Leporinus Agassiz (Characiformes: Anostomidae) from the rio Curuá, rio Xingu basin, Serra do Cachimbo, Brazil, with comments on Leporinus reticulatus, Neotropical Ichthyology 7 (1), pp. 1-10 : 2-4

Leporinus guttatus , new species

Figs. 1 , 2

Holotype. MZUSP 97100, 107.5 mm SL, Brazil, Altamira , rio Curuá , Iriri drainage (rio Xingu basin), upstream from PCH (=small hydroeletric dam) Buriti, 08 o 46’28”S 54 o 57’12”W, 21 Oct 2007, J. L. O. Birindelli, L. M. Sousa, A. Netto-Ferreira, M. H. Sabaj Pérez, N. Lujan.

Paratypes. Brazil, Pará, Altamira, Iriri drainage ( rio Xingu basin) . ANSP 189166 , 1, 106.4 mm SL ; INPA 30761 , 1, 103.1 mm SL ; MZUSP 99741 , 5 , 84.8-107.5 mm SL; collected with holotype . MZUSP 96865 (11, 70.6-108.5 mm SL, 1 cs, 96.5 mm SL), rio Curuá, cofferdam of PCH Buriti , 08 o 46’09”S 54 o 57’02”W, 21 Oct 2007, J. L. O. Birindelli et al . MZUSP 101300 (11, 96.4-124.7 mm SL, 2 sk, approximately 100 mm SL), rio Curuá , 08 o 45’55”S 54 o 57’04”W, 23 Jan 2009, J. L. O. Birindelli et al .

Diagnosis. Leporinus guttatus is diagnosed by its unique coloration, which consists of eight to ten midlateral round dark blotches, and 20 to 40 smaller ones forming one or two irregular series above and two or three irregular series below midlateral blotches.

Leporinus guttatus can be further distinguished from its congeners, except L. amae , L. bahiensis , L. bistriatus , L. garmani , L. marcgravii , L. megalepis , L. melanopleura , L. microphthalmus , L. octofasciatus , L. octomaculatus , L. paranensis , L. reticulatus , L. sexstriatus , L. striatus , L. taeniatus , L. taeniofasciatus , L. tigrinus , and L. uatumaensis by the dental formula 3/4 (vs. dental formulae 3/3, 4/4 or 4/3). Leporinus guttatus is distinguished from L. bahiensis , L. megalepis , L. melanopleura , L. octofasciatus , L. paranensis , L. striatus , L. taeniatus , L. taeniofasciatus , L. tigrinus , and L. uatumaensis by having 12 circumpeduncular scale series (vs. 16). Leporinus guttatus differs from L. amae , L. bistriatus , L. sexstriatus , and L. garmani by the presence of dark blotches on body (vs. dark longitudinal stripes in L. amae , L. bistriatus , L. sexstriatus , and only one dark blotch on caudal peduncle in L. garmani ). Leporinus guttatus differs from L. marcgravii , L. octomaculatus , and L. microphthalmus by the presence of eight to ten dark midlateral blotches on body (vs. six to eight large midlateral dark blotches over body), two or three irregular series of smaller dark blotches below the midlateral ones (vs. one) and, when compared to L. octomaculatus , by relatively short head in specimens larger than 90 mm SL (20.9-22.7, mean 21.7, n = 10; vs. 22.1-24.8, mean 23.1, n = 18). Leporinus guttatus is distinguished from L. reticulatus by the presence of round dark blotches on body (vs. irregular dark blotches), mouth subinferior to inferior (vs. subterminal to subinferior), and shorter head length (20.9 to 23.6, mean 22.3; vs. 26.0 to 30.8, mean 27.7).

Description. Morphometric data of holotype and paratypes in Table 1. Relatively small size, when compared to congeners, largest examined specimen 124.7 mm SL. Body elongate and moderately compressed. Dorsal profile gently convex from snout tip to dorsal-fin origin, straight from dorsal-fin origin to adipose-fin origin, and distinctly concave from adipose-fin origin to anteriormost dorsal caudal-fin procurrent rays. Ventral profile distinctly convex from lower jaw to posterior insertion of anal-fin rays, and gently concave from this point to origin of lower lobe of caudal-fin. Greatest body depth at dorsal-fin origin. Head somewhat compressed.

Mouth subinferior (reaching slightly ventrally to longitudinal through lower margin of orbit, in specimens around 80 mm SL) to inferior (reaching slightly ventrally to longitudinal through lower margin of infraorbitals, in specimens of 90 mm SL or more). Snout rounded to slightly acute in some specimens (as in holotype, see Fig.1a ). Premaxilla with three incisiform teeth gently diminishing in size from symphyseal tooth. Dentary with four incisiform teeth also gradually decreasing in size laterally ( Fig. 3 ).

Dorsal fin ii, 10 (20), origin slightly in front of vertical through pelvic-fin origin; fin-base six scales in length, distal margin convex. Pectoral fin i,13 (2), 14* (9), 15 (6) or 16 (3), extending through five to six scales from fin base, distal margin convex. Pelvic fin i,8 (20), extending through five scales, distal margin convex. Anal fin ii,8 (20), anal-fin origin at vertical through fifth scale anterior to adipose-fin origin; adpressed fin not reaching base of lower caudal-fin rays, distal margin straight or slightly convex. Caudal-fin rays i,8,9,i (20), forked, lobes rounded, upper lobe slightly more elongate than lower lobe. Vertebrae 35 (2) to 36 (4).

Scales with 5 to 7 radii. Lateral line complete with 37 (14) or 38* (6) perforated scales. Transversal series with 4 (20) scales from dorsal-fin origin to lateral line; 3 (12), 3.5 (6) or 4* (2) scales from lateral line to pelvic-fin base; and 3 (16) or 3.5* (4) scales from lateral line to anal-fin base. Predorsal scales 10 (5) or 11* (15). Twelve horizontal scale rows around caudal peduncle.

Coloration. Overall ground color tan. Head and body slightly countershaded, gradually darker above longitudinal line from mouth, through lower border of orbit to midline of opercle, and body above lateral line. Body with eight to ten dark round blotches along lateral line, three of them slightly larger and more conspicuous (one below posterior insertion of dorsal fin, one above anal-fin origin and one on caudal peduncle), Etymology. From the latin guttatus , meaning spotted or dappled, in allusion to the presence of the dark blotches scattered over the body, which are more numerous than those in any other known species of Leporinus . An adjective. and several (about 20 to 40) smaller blotches scattered over body. Smaller specimens, up to 80 mm SL, with fewer (around 20) smaller blotches forming one or two irregular series above and two or three irregular series below midlateral blotches ( Fig. 1b ). Larger specimens, from 90 mm SL, with more numerous (around 40) smaller blotches forming two to three irregular series below and above midlateral blotches ( Fig. 1a ). Ventral surfaces of head and body pale yellow to cream, without chromatophores. Adipose fin with dark distal margin. Remaining fins nearly hyaline, with few chromatophores along margins of rays.

Live coloration as describe above, except for overall ground coloration more tan than yellow ( Fig. 2 ).

Geographic distribution. Leporinus guttatus is known from the upper rio Curuá, above the great falls of Serra do Cachimbo ( Figs. 4 and 5 ). The rio Curuá is a tributary to the rio Iriri, a large tributary to the lower rio Xingu. The absence of L. guttatus from collections made below the waterfalls indicates that the new species might be restricted to the river portion isolated above the falls (see Birindelli et al., 2009 for discussion on the endemism of the upper rio Curuá Ichthyofauna).

Ecological notes. Specimens of Leporinus guttatus were caught in a clear water stream, near waterfalls (MZUSP 97100 and MZUSP 101300) or in a cofferdam just above a waterfall (MZUSP 96865). Fishes were caught most effectively by gill nets and cast net during the sunset.

Figures

Fig. 1. Leporinus guttatus, a - holotype, MZUSP 97100, 107.5 mm SL, b - paratype, MZUSP 96865, 81.3 mm SL, Brazil,Altamira, Pará State, rio Curuá.

Fig. 2. Leporinus guttatus, live specimen, paratype, MZUSP 101300, 124.7 mm SL.

Fig. 3. Leporinus guttatus, paratype, MZUSP 96865, 96.5 mm SL. Upper and lower jaws, in frontal and lateral views respectively.

Fig. 4. Distribution of Leporinus guttatus in the rio Curuá, rio Xingu basin, central Brazil (type locality represented by open circle).

Fig. 5. Rio Curuá, above the great falls, showing one of the collection sites of Leporinus guttatus.