Lepidocharax burnsi, Ferreira & Menezes & Quagio-Grassioto, 2011

Ferreira, Katiane M., Menezes, Naércio A. & Quagio-Grassioto, Irani, 2011, A new genus and two new species of Stevardiinae (Characiformes: Characidae) with a hypothesis on their relationships based on morphological and histological data, Neotropical Ichthyology 9 (2), pp. 281-298 : 286-288

Lepidocharax burnsi , new species

Fig. 7

Holotype. MCP 45718, 34.4 mm SL, female, Brazil, Brumadinho , rio Paraopeba, São Francisco basin, approx. 20º09’S 44º10”W, Apr 1997, V. Vono & C. B. M. Alves.

Paratypes. All from Brazil, Minas Gerais, São Francisco basin: CPUFMT 31, 16, 19.2-25.9 mm SL (2, 19.1-26.8 mm SL), Riachinho , rio Urucuia , córrego Santa Cruz , 16º27’16”S 45º47’22”W, 10 Apr 2009, A. C. Ribeiro. LIRP 2069, 16, 26.8-33.8 (6, 30.1-33.8 mm SL), Presidente Olegário , upper rio da Prata, córrego São João , fazenda Devaneio , 18º23”S 46º16”W, 14 Oct 2000, A. C. Ribeiro. LIRP 4160, 147, 19.2-33.3 mm SL (17, 26.3-33.5 mm SL), Felixlândia , córrego do Brito , 27 Jan 2002, A. Melo. MCP 27824, 1, 30.2 mm SL, Paracatu, 17º18’15”S 46º46’16”W, 24 Jan 2001, C. Lucena, J. Silva, E. Pereira & A. Cardoso. MCP 27829, 128, 20.2- 32.2 mm SL (17, 22.6-32.2 mm SL), Guarda-Mor, rio Piratininga , 17º56’39”S 46º58’08”W, 25 Jan 2001, C. Lucena, J. Silva, E. Pereira & A. Cardoso. MCP 31798, 1, 29.7 mm SL, collected with holotype; MCP 34684, 2, 26.0- 28.3 mm SL, córrego São Miguel, 20º12’00”S 45º39’09”W, 26 Sep 2003, B. P. Nogueira. MCP 34828, 24, 21.4- 32.4 mm SL (15, 22.6-32.5 mm SL), Guarda-Mor, córrego Macaúba, 17º58’57”S 47º06’41”W, 24 Jan 2001, C. Lucena, J. Silva, E. Pereira & A. Cardoso; MZUSP 39190, 31, 19.3-29.3 mm SL (2, 28.5-29.3 mm SL), córrego Gameleira, 27 Nov 1987, Y. Sato, UHE Formoso project. MZUSP 39651, 4, 32.3-39.9 mm SL (3, 35.7-39.9 mm SL), rio Abaeté , córrego Chumbo, 18 Mar 1988, Y. Sato, UHE Formoso project .

Non-type specimens. MCP 27915, 36, 20.2-32.8 mm SL (16, 22.6-31.9 mm SL), rio Vermelho , rio Doce basin, 18º17’S 43º01’W, 5 Oct 1996, H. G. Evers .

Body laterally compressed, moderately elongate, largest specimen 38.8 mm SL. Greatest body depth situated at dorsalfin origin. Dorsal profile of head slightly convex from margin of upper lip to tip of supraoccipital spine; slightly convex from tip of supraoccipital spine to dorsal-fin origin; straight along dorsal-fin base; straight from posterior terminus of dorsal-fin base to adipose-fin insertion, and slightly concave from latter point to caudal-fin origin. Ventral profile of body convex from tip of lower jaw to anal-fin insertion and slightly concave ventral to caudal peduncle; anal-fin base straight.

Dorsal-fin rays ii,7(1) or 8*(51). Length of first unbranched dorsal-fin ray less than one-half length of second unbranched ray.Adipose fin present. Length of adipose fin base in a vertical above bases of last three anal-fin rays. Pectoral-fin rays i,8(4), 9*(44) or 10(3),i. Pelvic fin rays i,5,i*(52). Anal fin with four unbranched rays followed by 21(2), 22(8), 23*(17), 24(16), 25(5), or 26(2) branched rays. Sexually mature males with hooks on anal-and pelvic-fin rays. On anal-fin, hooks are very small and located on segments from largest unbranched ray until de 10- 13 th branched ray ( Fig. 8 ). Usually, there are three hooks per ray. On pelvic-fin, hooks also are numerous and small, and present on segments of all branched rays. Caudal-fin forked; lobes similar in size. Principal caudal-fin rays i,17,i*(52).

Premaxilla extending slightly anterior of vertical through tip of dentary. Premaxilla with two rows of teeth ( Fig. 9 ). Outer tooth row aligned in gentle arch, with 3(2) or 4*(48) tricuspid teeth, with median cusps largest. Inner premaxillary tooth row with 4(34) or 5*(14) teeth. Symphyseal tooth in row with four cusps and remaining teeth with five cusps. Maxilla with 2*(40), Diagnosis. Lepidocharax burnsi can be distinguished from L. diamantina by its deeper head (18.7-25.0 vs. 16.7-18.8% SL); by possessing fewer longitudinal scale rows between the lateral-line and the pelvic-fin origin (6-7 vs. 8); fewer lateralline scales (39-46 [41] vs. 47-56 [54]); and more branched analfin rays (21-26 [23] vs. 19-22 [22]).

Description. Morphometric and meristic data for holotype and paratypes presented in Table 2.

3(9) or 4(2) tricuspid teeth with median cusps slightly more developed. Dentary with four large anterior teeth with five cusps followed by smaller teeth with three to five cusps.

Scales cycloid. Lateral line complete, with 39(1), 40(13), 41*(16), 42(12), 43(4), 44(3), 45(1), or 46(1) perforated scales. Six*(43), or 7(8) longitudinal scale rows between dorsal-fin origin and lateral line four*(27) or 5(24) between lateral line and pelvic-fin origin. Predorsal scales 14(1), 15(7), 16*(18), 17(18), 18(6), or 19(1). Circumpeduncular longitudinal scale rows 14-18. Single row of seven to ten scales extending along base of anal fin. Basal portion of both caudal-fin lobes covered with medium size scales, about as large as scales on caudal peduncle ( Fig. 10).

First gill arch with 9(2), 10(28), or 11*(21) gill rakers on hypobranchial and ceratobranchial, 5(8)*, 6(41), or 7(2), rakers on epibranchial and 1 raker on cartilage between ceratobranchial and epibranchial.

Color in alcohol. Head and body of specimens retaining guanine on scales, therefore somewhat silvery. Overall ground coloration yellowish tan. Dorsal surface of head and lips with dense concentration of dark chromatophores. Scattered dark chromatophores covering only upper region of opercle. Dark chromatophores concentrated on predorsal scales. Concentration of chromatophores decreasing progressively from middorsal region to lateral line, where limited to edges of scales. Chromatophores absent on scales of abdominal region below lateral line. Chromatophores present between lateral line and anal fin. Midlateral stripe on body extending from behind upper part of opercle to caudal peduncle. Dorsal, pectoral, pelvic, and caudal fins hyaline, with scattered dark chromatophores outlining rays and forming straight lines. Dark chromatophores concentrated along distal borders of interradial membranes of anal fin base. Adipose fin clear, with small, dark chromatophores concentrated on posterior base of fin.

Distribution. This species was collected from tributaries of the upper rio São Francisco and rio Doce basins ( Fig. 6).

Etymology. Lepidocharax burnsi is named in honor of John R. Burns for his outstanding contribution to the knowledge of histology of small inseminating characids.

Sexual dimorphism. Sexually mature males of the two new species have hooks on anal-and pelvic-fin rays, and proportionally longer pectoral and pelvic-fins, the tip of the former reaching pelvic-fin origin, and the tip of the latter reaching anal-fin origin.

Histological analysis. The two new species have spermatozoa with ovoid nuclei, and packs of spermatozoa were observed within the ovaries of females ( Fig. 11 ). Sexually mature males of both new species also have gill glands, consisting of modifications the first gill arches and the development of five gill filaments and four chambers.

Figures

Fig. 7. Lepidocharax burnsi, holotype, female, MCP 45718, 34.4 mm SL: Brazil, Minas Gerais, Brumadinho, rio Paraopeba.

Fig. 8. Hooks on anal-fin rays of Lepidocharax burnsi, LIRP 2069, paratype, 34.0 mm SL, adult male.

Fig. 9. Lepidocharax burnsi, LIRP 2069, paratype, 34.0 mm SL, adult male. Upper and lower jaws, right side, lateral view. Scale bar = 1 mm.

Fig. 11. Light micrographs through mature ovaries of Lepidocharax. Arrows show spermatozoa (sp). A: Lepidocharax diamantina (MNRJ 21997, 40.4 mm SL). B: Lepidocharax burnsi (MCP 34828, 29.9 mm SL).