Characidium clistenesi Melo & Espíndola, 2016, new species

Characidium clistenesi, new species

Piaba-charuto, charutinho

(Figs. 1 A–C, 2A–E, 3A–B, Table 1)

Characidium bimaculatum (non Fowler, 1941): Leitão & Buckup, 2014: 21 (material examined, in part. MNRJ 23757, 23764, both from rio São José, Lençóis, Bahia).

Characidium cf. bimaculatum (non Fowler, 1941): Santos, 2003: 27, 75, 77, 78 (checklist and estimative of abundance of species from rio Paraguaçu, Chapada Diamantina).

Holotype. MZUSP 120530, 27.4 mm SL, Rio Capivara, tributary of rio Paraguaçu, Chapada Diamantina, Lençóis, Bahia, Brazil, 12°27’27”S, 41°22’35.7”W, 31 Oct 2015, M.R.S. Melo, A.C.A. Santos, E. Santos, P. Moura, and C. Santos

Paratypes. All from rio Paraguaçu Basin, Chapada Diamantina, Bahia, Brazil: MNRJ 47511, 20, 24.3–30.3 mm SL, MZUSP 120532, 70 (3 CS), 22.8–34.7 mm SL, ZUEC 13030, 20, 25.1–31.0 mm SL, collected with holotype; MZFS 7214, 3, 31.7–36.9 mm SL, Ribeirão de Baixo, Lençóis, 12°35’10”S, 41°22’ 57.1”W, 3 Sept 2005, A.C.A. Santos; MZFS 13782, 4, 26.2–35.3 mm SL, rio Paraguaçu, Utinga, 12°06’44”S, 41°07’15”W, 11 Aug 2008, A.C.A. Santos; MZFS 14554, 1, 27.4 mm SL, Ribeirão de Baixo, Lençóis, 12°35’10”S, 41°22’57”W, 2 Jul 2010, A.C.A. Santos; MZFS 15189, 1, 29.0 mm SL, Rio Caldeirão, Lençóis, 12°39’33”S, 41°22’13”W, 21 Sept 2012, A.C.A. Santos; MZFS 15208, 4, 38.0– 42.7 mm SL, rio Capivara, tributary of rio Paraguaçu, Lençóis, 21 Sept 2012, A.C.A. Santos; MZFS 15225, 7, 32.6–40.3 mm SL, rio Roncador, downstream from Poço do Roncador, Andaraí, 21 Sept 2012, A.C.A. Santos; MZFS 16548, 2, 22.7–23.5 mm SL, córrego dos Padres, Andaraí, 28 May 2014, A.C.A. Santos; MZFS 17012, 1, 28.7 mm SL, rio Caldeirão, Lençóis, 21 Sept 2012, A.C.A. Santos; MZFS 17014, 1, 25.5 mm SL; MZFS 17015, 2, 27.8–28.3 mm SL, rio Capivara, Lençóis, 14 Jul 2013, A.C.A. Santos; MZFS 17072, 40, 27.1–32.5 mm SL, rio São José, Lençóis, 12°37’27,1’’S, 41°22’35.7”W, 31 Mar 2016, P.E.S.

Moura, M. Carvalho, D. Vinicius & V.C. Espíndola; MZFS 17078, 5, 27.1–33.2 mm SL, rio São José, Lençóis, 11 Mar 2016, P.E.S. Moura, M. Carvalho, D. Vinicius, V.C. Espíndola; MZUSP 120464, 24, 26.4–32.4 mm SL, rio Capivara, tributary of rio São José, Lençóis, 12°37’24”S, 41°22’33”W, 20 Jul 2016, M.R.S. Melo, V.C. Espíndola, P.E.S. Moura; MZUSP 120474, 22, 26.8–34.8 mm SL, ribeirão de Baixo, tributary of rio São José, Lençóis, 12°39’32”S, 41°22’12.5”W, 20 Jul 2016, M.R.S. Melo, V.C. Espíndola, P.E.S. Moura; MZUSP 120487, 22, 24.5– 31.7 mm SL, rio São José at crossing with BR 272, Balneário do rio São José, Lençóis, 20 Jul 2016, M.R.S. Melo, A.V.C. Espíndola, P.E.S. Moura; MZUSP 120547 (former MZFS 17095), 39, 20.1–23.6 mm SL, tributary of rio Paraguaçu, Lençóis, 15 Oct 2014, A.C.A. Santos; MZUSP 120548 (former MZFS 17097), 1, 29.8 mm SL, rio Capivara, tributary of rio Paraguaçu, Lençóis, 13 Dec 2013, A.C.A. Santos; MZUSP 120549 (former MZFS 17093), 11, 18.5–24.4 mm SL, rio Santo Antônio, tributary of rio Paraguaçu, Lençóis, 15 Oct 2014, A.C.A. Santos; MZUSP 120550 (former MZFS 17094), 19, 19.6–30.8 mm SL, rio Santo Antônio, tributary of rio Paraguaçu, Lençóis, 15 Oct 2014; A.C.A. Santos; MZUSP 120551 (former MZFS 17096), 10, 24.8–33.8 mm SL, rio Capivara, tributary of rio Paraguaçu, Lençóis, 14 Dec 2013, A.C.A. Santos; MZUSP 120552 (former MZFS 17098), 3, 32.8– 26.6 mm SL, Córrego dos padres, tributary of rio Paraguaçu, Lençóis, 28 May 2014, A.C.A. Santos.

Diagnosis. Characidium clistenesi can be distinguished from its congeners except C. bahiense, C. bimaculatum, C. laterale, C. nana, C. nupelia and C. xavante by having a conspicuous peduncular blotch (vs. peduncular blotch absent). It can be distinguished from C. bahiense, C. nana, C. nupelia, and C. xavante by having a complete lateral line with 32–36 perforated scales (vs. lateral line short, not reaching level of dorsal-fin origin, with five to eleven perforated scales), and from C. bimaculatum by the presence of secondary bars in addition to primary bars, total bars 11–16 (vs. secondary bars absent, total bars 10–11), peduncular blotch rounded (vs. peduncular blotch horizontally elongated), and mature males with dorsal fin mostly hyaline with a band of melanophores on its proximal third and sparse melanophores between branches of dorsal-fin rays (vs. mature males with proximal third of dorsal fin dark). Characidium clistenesi further differs from C. bimaculatum and C. xavante by having 12–13 circumpeduncular scales (vs. 14 in C. bimaculatum and 10 in C. xavante); from C. nana by having well-elongated bars, reaching abdominal region (vs. transversal bars absent or short, not reaching midbody), stripe thinner than a scale (vs. stripe stout and wide, covering from one to one and a half scales), adipose fin present (vs. absent), and presence of hooks on branched pelvic-fin rays in mature males (vs. hooks absent); and C. bahiense by having secondary bars in addition to primary bars (vs. only primary bars present).

Description. Morphometric data summarized in Table 1. Small species of Characidium, reaching maximum size of 42.7 mm SL. Body elongated, dorsal profile moderately convex between tip of snout and dorsal-fin origin, gently arched at dorsal-fin base, almost straight between dorsal and caudal-fin bases. Ventral profile gently convex between anterior tip of dentary and anal-fin origin, slightly concave at anal-fin base; almost straight between anal and caudal-fin bases. Belly strongly arched in females with ovaries well developed. Greatest depth of body at dorsal-fin origin.

Snout short, gently rounded in lateral view, its tip at level of inferior margin of eye. Mouth small, terminal in juveniles (Fig. 2 A, B), subterminal in adults (Fig. 2 C, D). Maxilla reaching level of anterior margin of orbit. Orbit rounded or slightly elongated anterodorsally; margin of orbit free. Cheek depth about one third of eye diameter. Nares separated; distance between nares shorter than distance between posterior naris and eye. Dermal flap along entire border of anterior naris, crescent-shaped and restricted to anterior margin of posterior naris. Parietal branch of supraorbital laterosensory canal present. Fontanel limited anteriorly by frontals, posteriorly by parietals. Dentary teeth tricuspid, arranged in single row, increasing in size from lateral to medial, numbering 5(1), 6*(7), 7(6), 8(10), 9(6). Premaxillary teeth tricuspid, arranged in single row, increasing in size from lateral to medial portion, numbering 5(4), 6*(18), 7(8). Maxillary teeth absent. Ectopterygoid teeth arranged in single row, conical, small, 6(1), 7(1), 11(1). Mesopterygoid teeth absent. Branchiostegal rays 4(3); two attached to anterior ceratohyal (3). Total gill rakers on first arch 7(1), 8(1), 10(1); gill rakers attached to epibranchial 3(1), 4(2); gill rakers attached to ceratobranchial 4(2), 6(1).

Scales cycloid; parallel radii present on posterior field of scale, circuli absent. Lateral line complete; lateralline scales 32(2), 33*(7), 34(19), 35(1), 36(1). Scales above lateral line 4*(30). Scales below lateral line 5*(28), 6(2). Circumpeduncular scales 12*(29), 13(1). Predorsal scales regularly distributed, numbering 9*(4), 10(23), 11(3). Scales between anus and anal-fin origin 2*(12), 3(16), 4(1) 5(1). Isthmus scaled.

Pectoral-fin rays iv,6,i(1), ii,6,ii(2), iii,7,i(8), iii,7,ii(12), iii,8,i(3), iii,8,ii(3), iii,9,i*(1). Pelvic-fin rays i,6,i(2), i,6,ii(3), i,7,i*(23), i,7,ii(1), i,8,i(1). Dorsal-fin rays ii,9*(29), ii,10(1); supranumerary element on first pterygiophore of dorsal fin 1(1). Anal-fin rays ii,6*(30); supranumerary element on first pterygiophore of anal fin 1(1). Principal caudal-fin rays i,8,8,i*(1), i,8,9,i(29), i,9,9,i(3). Adipose fin present (30).

Precaudal vertebrae 18(3); total vertebrae 33(2), 34(1). Lower procurrent rays 6(3); upper procurrent rays 7(3). Hypurals 6(3). Epurals 2(3). Posterior chamber of swim bladder reduced, with same size as anterior chamber.

Color of preserved specimens. Ground color of head and trunk tan (Figs. 1 A–C, 2A–C). Cheek, distal portion of upper jaw, ventral part of head and opercle pale spotted with widely spaced melanophores. Dorsal portion of snout and head brown. Dorsal portion of body dark brown; body beige; belly pale beige to whitish. Single, midlateral stripe present, stout, extending from tip of snout to posterodorsal angle of opercle on head, continuing along midbody dorsal to lateral line, extending along base of middle caudal-fin rays. Eyes black with ventral margin silver. Humeral blotch vertically elongated, over posttemporal and supracleithrum, overlapped by longitudinal stripe. Peduncular blotch brown, rounded. Basicaudal spot rounded, on base of middle caudal-fin rays, connected with peduncular blotch anteriorly.

Melanophores more concentrated on posterior edge of scales, forming chain-like bars; primary and secondary bars present, total bars on body 11–16, irregularly distributed, fused along dorsal midline; extending ventrally on flank, not connected ventrally on midline on belly; connected ventrally on midline at level of anus and caudal peduncle. Last bar of body overlapped by peduncular botch. Total bars 11*(2), 12(6), 13(9), 14(7), 15(4), 16(1). Pectoral, pelvic and anal fins mostly hyaline, with melanophores concentrated at edges of lepidotrichia. Dorsal fin mostly hyaline, with melanophores concentrated at margin of lepidotrichia, a single band of melanophores present, on proximal third of dorsal fin, and on interradial membrane between branches of dorsal-fin branched rays. Adipose fin with melanophores widely spaced. Caudal fin with melanophores concentrated on margins of lepidotrichia.

Color in life. Description based on field observations. Most specimens observed on field pale yellow, with bars poorly marked. Yellow areas more evident on opercle, cleithrum and base of pectoral fin. Longitudinal stripe, peduncular blotch and basicaudal spot evident (Fig. 3 A). Few specimens in nature considerably darker, with ground color of body color light-olive-green, bars well marked and base of dorsal fin yellowish (Figs. 2 A, 3B).

Sexual dimorphism. No sexual dimorphism of color pattern. All mature males with numerous hooks on lepidotrichia of first to fifth branched pelvic-fin rays. Few mature males (MZUSP 120532, 1 specimen, 27.5 mm SL; MZFS 15225, 1 specimen, 32.6 mm SL) also having hooks on first and second branched pectoral-fin rays. Adult females and juveniles lacking hooks on fin rays. Smallest male with hooks on pelvic-fin rays at 23.3 mm SL (MZFS 15225).

Distribution. Characidium clistenesi is apparently endemic to streams draining the eastern side of the Chapada Diamantina Plateau, draining into rio Paraguaçu, a coastal drainage from Bahia, Brazil (Fig. 4).

Habitat. Streams with clear, fast-flowing water with rapids and small pools, and sand, gravel or rocky bottom. Etymology. The specific name is dedicated to our colleague Dr. Alexandre Clistenes de Alcântara Santos, in recognition of his long time of dedication in researching the natural history of the ichthyofauna of the Chapada Diamantina, Bahia, Brazil.