Lebiasina melanoguttata, Netto-Ferreira, 2012

Netto-Ferreira, André L., 2012, Three new species of Lebiasina (Characiformes: Lebiasinidae) from the Brazilian Shield border at Serra do Cachimbo, Pará, Brazil, Neotropical Ichthyology 10 (3), pp. 487-498 : 491-494

Lebiasina melanoguttata , new species

Fig. 5

Lebiasina sp. - Sabaj Pérez, 2009: 40 [trip report]; Birindelli et al., 2009: 14 [trip report].

Holotype. MZUSP 99609 , 85.9 mm SL, Brazil, Pará, Altamira, rio Xingu drainage, unnamed tributary of rio Curuá , rio Iriri basin, near BR-163, 08°49’12”S 54°58’11”W, 29 Oct 2007, A. L. Netto-Ferreira, L. M. Sousa, J. L. O. Birindelli, M. H. Sabaj Pérez & N. K. Lujan.

Paratypes. Brazil, Pará, Altamira : ANSP 192061 , 5 , 77.2-81.3 mm SL , MZUSP 99610 , 22 , 41.73-93.53 mm SL; 3 cs, 72.51- 89.41, same data as holotype ; MZUSP 99611 , 12 , 6.17-32.26 mm SL, rio Xingu drainage, unnamed tributary of rio Curuá, rio Iriri basin, near BR-163 road, 08°47’03”S 54°58’29”W, 29 Oct 2007, A. L. Netto-Ferreira, L. M. Sousa, J. L. O. Birindelli, M. H. Sabaj Pérez & N. K. Lujan ; MZUSP 101382 , 9 , 43.1-110.2 mm SL, rio Xingu drainage, unnamed tributary of rio Curuá, rio Iriri basin, near BR-163 road, 08°49’12”S 54°58’11”W, 22 Jan 2009, A. L. Netto-Ferreira, L. M. Sousa, J. L. O. Birindelli & P. Hollanda-Carvalho .

Diagnosis. Lebiasina melanoguttata is readily distinguished from all lebiasinins (except for L. minuta ) by the absence of the primary and secondary stripes, and the caudal blotch; the presence of three longitudinal series of dark blotches at the base of the scales; the pair of foramina on the vomer through which the ramus palatinus of the facial nerve runs ( Fig. 2a ); the large laminar extrascapular bone in contact with the fifth infraorbital, and overlaying the anterodorsal portion of the opercle; and nearly equal caudal-fin lobes. Lebiasina melanoguttata differs from Lebiasina minuta by the absence of a dark blotch at the base of the median rays of the dorsal-fin, the presence of conical teeth on the second infrapharyngobranchial, the reddish overall coloration of the eye and fins, and the dark blotches of longitudinal series 3 and 4 which never coalesce (vs. a dark blotch present at the base of the median rays of the dorsal-fin; the second infrapharyngobranchial being edentulous; a yellowish overall color of body, and the dark, olive green eyes; and the dark blotches of longitudinal series 3 and 4 coalescing where scales of adjacent longitudinal series overlap).

Description. Morphometric data of holotype and paratypes presented in Table 2. Lateral view of holotype and live specimen shown in Figs 5a and 5c , respectively. Body cylindrical, elongate. Dorsal profile of head convex from tip of upper lip to vertical through anterior nostrils; nearly straight from latter point to base of scales covering posterior half of parietals. Body profile nearly straight to base of dorsal fin, and distinctly concave from that point to origin of anteriormost dorsal procurrent ray of caudal fin. Ventral profile of head and trunk distinctly convex from lower lip to pelvic-fin origin; nearly straight from that point to anal-fin origin; convex along anal-fin base, and nearly straight from anal-fin terminus to origin of anteriormost ventral procurrent ray of caudal fin.

Mouth sub-superior. Premaxillary with single row of 11(2) or 13(1) tricuspid teeth. Maxillary with 4(3) tricuspid teeth. Anteriormost tooth usually largest. Posterior terminus of maxilla reaching to, or extending slightly beyond, anterior margin of orbit. Dentary with two series of teeth; outer series with 13(1), 14(1) or 15(1) pedunculate tricuspid teeth with central cusp distinctly longer than lateral marginal cusps, teeth gradually decreasing in size posteriorly. Inner tooth series with several minute conical teeth extending from symphysis to coronoid process. Branchiostegal rays 4(3); three rays originating from anterior ceratohyal and one from posterior ceratohyal.

Scales cycloid, circuli restricted to border of scales, several radii (around 32) converging to center of scale and strongly anastomosed in center and forming several cells. Lateral line series with 26(1), 27(12), or 28*(8) scales, of which only 4(1), 5*(6), or 6(2) are perforated. Longitudinal rows of scales between dorsal and pelvic fins 7*(21). Predorsal scales 12(4), 13*(13) or 14(4). Circumpeduncular scales 12*(21).

Pectoral-fin rays i,12(1), 13(8), 14*(17), or 15(4).Tip of longest pectoral-fin ray falling far short of vertical through pelvic-fin insertion. Pelvic-fin rays i,7*(21). Supraneurals 11(3), anterior to neural spine of centra 5 to 15(3). Dorsal-fin rays ii,8*(21). First dorsal-fin pterygiophore inserting behind neural spine of centrum 15(3). Distal margin of extended dorsal fin rounded. Dorsal-fin origin distinctly closer to caudal-fin origin than to tip of snout. Base of last dorsal-fin ray located distinctly anterior to vertical through anal-fin origin.Anal-fin rays iii,8*(20) or iii,9(1), with last ray adnate. Distal margin of extended anal fin rounded. First anal-fin pterygiophore inserted posterior to haemal spine of centrum 22(3).Adipose fin absent. Caudal fin furcate with upper lobe slightly longer than lower lobe; both lobes rounded. Caudal-fin principal rays ii,8/i,8*(11), i,9/i,8(8). Dorsal procurrent caudal-fin rays 6(2) or 7(1); ventral procurrent caudal-fin rays 7(2) or 8(1). Precaudal vertebrae 21(3); caudal vertebrae 15(3).

Color in alcohol. Background color predominantly brown. Head densely pigmented from upper lip to first scales overlying portion of parietal. Dark brown pigmentation extending from that point to insertion of caudal fin, along mid-dorsal series of scales and immediately bordering scale rows. Maxilla, circumorbital bones and opercular series dark, becoming lighter ventrally. Lower lip densely pigmented. Ventral portion of head with scarce pigmentation. Opercular membrane with small scattered chromatophores.

Trunk dark dorsally, becoming lighter ventrally from third longitudinal series of scales. Abdominal region yellowish, with minute dark chromatophores from isthmus to anal-fin origin. Humeral blotch rounded; more conspicuous in juvenile and smaller adult specimens but inconspicuous in large adults (60.0-65.0 mm SL) due to dark overall pigmentation of body. Primary and secondary longitudinal stripes absent. Three longitudinal series of dark blotches at base of scales of longitudinal series 3 to 5; dark blotches never coalescing. Caudal blotch absent. Dark pigmentation present along rays and intervening membranes of all fins.

Color in life. Same as in alcohol, except for red eyes and fins; reddish ventral portion of head; and pearly coloration on scales of longitudinal series 3 to 6 posterior to dark blotches ( Fig. 5c ).

Sexual dimorphism. As in most lebiasinids, mature male specimens of Lebiasina melanoguttata possess several modifications in the anal fin including: longer and thicker anal-fin rays similar to the condition observed in Ctenolucius ( Vari, 1995) , some alestids ( Zanata & Vari, 2005) and Hoplerythrinus ; anal-fin rays with thickened membranes, a condition also shared with Hoplerythrinus ; very developed anal-fin rays erectors and depressors muscles, as also observed in Hoplerythrinus and the characid genera Attonitus and Bryconadenos ( Vari & Ortega, 2000; Weitzman et al., 2005); and breeding tubercles on the infraorbital bones, opercle and subopercle, lateral surface of pectoral- and pelvic-fin rays, posterior border of scales on the sides of the body and caudal-fin rays. Among examined lebiasinids, breeding tubercles are also present in Nannostomus beckfordi , N. bifasciatus , N. limatus , N. marginatus , and N. nitidus , but in these species the tubercles are restricted to the anteroventral surface of the head, instead of distributed along the body.

Distribution. Lebiasina melanoguttata is known from two tributaries of the rio Curuá (rio Xingu basin) in Serra do Cachimbo ( Fig. 4 ).

Etymology. The specific epithet melanoguttata (melan- = black; guttata = dotted) is in reference to the longitudinal series of dark blotches present along the flanks of Lebiasina melanoguttata . An adjective.

Figures

Fig. 5. Lebiasina melanoguttata: a) preserved holotype, MZUSP 99609, 85.9 mm SL,Altamira, Pará, Brazil; b) female paratype, MZUSP 99610, 93.5 mm SL,Altamira,Pará,Brazil; c) fresh paratype, MZUSP 99611, 62.1 mm SL,Altamira, Pará,Brazil, showing live color pattern.

Fig. 2. Ventral view of medioanterior portion of the neurocranium of: a) Lebiasina melanoguttata, MZUSP 99610, paratype, 89.4 mm SL,Altamira, Pará, Brazil; b) Lebiasina ortegai CAR145, 94.5 mm SL,Alcalá, Valle del Cauca, Colombia.FRO - frontal; LAT - lateral ethmoid; MES - mesethmoid; NAS - nasal; ORB - orbitoshpenoid; PAR - parasphenoid; PTE - pterosphenoid; SPH - sphenotic; VOM - vomer.

Fig. 4. Map of rio Tapajós basin and adjoining areas, showing the distribution of Lebiasina marilynae n. sp. (star); Lebiasina melanoguttata n. sp. (circle); Lebiasina minuta n. sp. (triangle). Symbols may represent more than one collection event.