Hemigrammus tocantinsi, Carvalho & Bertaco & Jerep, 2010

Carvalho, Fernando R., Bertaco, Vinicius A. & Jerep, Fernando C., 2010, Hemigrammus tocantinsi: a new species from the upper rio Tocantins basin, Central Brazil (Characiformes: Characidae), Neotropical Ichthyology 8 (2), pp. 247-254 : 248-251

Hemigrammus tocantinsi , new species

Figs. 1 , 2 , 3a , 4

Holotype. MCP 44444, 28.2 mm SL, male, Brazil, Goiás, Cavalcante, rio das Pedras, Fazenda Córrego Fundo , 13º44’34’’S 47º26’33’’W, 8 Sep 2009, F. R. Carvalho, V. A. Bertaco & G. L. C. Frainer.

Paratypes. Brazil, Goiás State, municipality of Cavalcante , upper rio Tocantins basin. MCP 44508, 20 , 22.8-26.8 mm SL ; MNRJ 36005 , 20 , 23.8-29.9 mm SL ; MZUSP 105072 , 20 , 23.4-26.7 mm SL ; UFRGS 11300 , 146 (36), 23.9-32.8 mm SL (5 c&s, 25.3-29.1 mm SL) ; UFRGS 11836 , 8 (ethyl alcohol anhydrous), 24.7-28.6 mm SL ; UNT 9760 , 15 , 23.3-27.2 mm SL, collected with the holotype . UFRGS 9907 , 10 (3), 25.9-27.6 mm SL, córrego Grotão or Maria Rita on GO 241 road, between Cavalcante and Minaçu, about 4 km north of Cavalcante , 13º45’18’’S 47º27’20’’W, 25 May 2008 , F. C. Jerep & T. P. Carvalho . UFRGS 9910 , 31 (5), 25.7-36.8 mm SL, stream about 3.5 km north of Cavalcante on GO 241 road, between Cavalcante and Minaçu, 13º45’32’’S 47º27’20’’W, 25 May 2008 , F. C. Jerep & T. P. Carvalho . UFRGS 11292 , 6 (2), 25.0- 30.2 mm SL, same data as UFRGS 9910, 8 Sep 2009 , F. R. Carvalho , V.A. Bertaco & G. L. C. Frainer . UFRGS 11293 , 2 (1), 31.3 mm SL, córrego Lava- Pés , about 300 m of road GO 241 road, 2 km Northeast of Cavalcante, 13º47’17’’S 47º26’27’’W, 8 Sep 2009 , F. R. Carvalho , V. A. Bertaco & G. L. C. Frainer . UFRGS 11294 , 61 (11), same data as UFRGS 9907, 6 Sep 2009 , F. R. Carvalho , V. A. Bertaco & G. L. C. Frainer .

Diagnosis. Hemigrammus tocantinsi differs from most congeners [except H. bellottii (Steindachner) , H. bleheri Géry & Mahnert , H. boesemani Géry , H. brevis Ellis , H. cylindricus Durbin , H. cupreus Durbin , H. erythrozonus Durbin , H. geisleri Zarske & Géry , H. levis Durbin , H. mahnerti Uj & Géry , H. microstomus Durbin , H. mimus Böhlke , H. orthus Durbin , H. rhodostomus Ahl , H. rodwayi Durbin , H. tridens Eigenmann , H. skolioplatus Bertaco & Carvalho , and H. vorderwinkleri Géry ] by the number of branched anal-fin rays, 15-17 (vs. less than 15 in H. analis Durbin , H. hyanuary Durbin , H. iota Durbin , and more than 17 on remaining species). From the species with the same range of branched anal-fin rays, Hemigrammus tocantinsi differs by the presence of 1-2 (mode 1) maxillary teeth (vs. 3-11 in H. bellottii , H. cylindricus , H. cupreus , H. mimus , and H. skolioplatus ); longitudinal stripe posteriorly broad, larger than one scale depth or than pupil diameter (vs. thinner than one scale depth or pupil diameter or longitudinal stripe absent in H. bellottii , H. boesemani , H. brevis , H. erythrozonus , H. geisleri , H. levis , H. mahnerti , H. microstomus , H. orthus , H. rodwayi , H. tridens , and H. vorderwinkleri ); caudal-fin lobes hyaline (vs. presence of a conspicuous broad black marginal or submarginal band across the distal part of caudal-fin lobes in H. bleheri and H. rhodostomus ). Furthermore, Hemigrammus tocantinsi can be distinguished from all congeners by the color pattern of live specimens (reddish or orange in male and yellowish pigmented in female).

Description. Morphometric data summarized in Table 1. Body compressed, moderately short, greatest body depth at vertical through dorsal-fin origin. Dorsal profile of head convex from tip of upper jaw to vertical through anterior nostril; slightly straight or convex from that point to tip of supraoccipital spine. Dorsal profile of body slightly convex from posterior tip of supraoccipital spine to base of last dorsal-fin ray, and straight to adipose-fin origin. Ventral profile of body convex from tip of lower jaw to pelvic-fin origin, straight or slightly convex from that point to anal-fin origin, and straight and posterodorsally slanted along anal-fin base. Dorsal and ventral profile of caudal peduncle approximately straight.

Eyes large, without distinct adipose eyelid. Jaw isognathous, mouth terminal. Maxilla extending posteriorly surpassing vertical through anterior margin of eye, aligned approximately at 45 degree angle relative to longitudinal axis of body. Nostrils close to each other, anterior opening smaller and circular, posterior one twice larger and oval. Median frontoparietal fontanel extending from mesethmoid to supraoccipital spine. Infraorbital series complete, with fourth infraorbital reduced dorsally (triangular shape) or absent sometimes, allowing contact between third and fifth infraorbitals. Infraorbital laterosensory canal close to inferior orbital margin, extending from posterior half of first infraorbital up to sixth orbital. Third infraorbital largest, double size of the others (in length and depth), contacting the preopercle laterosensory canal ventrally and posteriorly.

Premaxillary teeth in two rows: outer with 2(10), 3*(39), or 4(10) tricuspid teeth (rarely pentacuspid); inner row with 4(13) or 5*(46) pentacuspid teeth. Dentary with 4*(54) or 5(5) large pentacuspid teeth, followed by a series of 4-6 small conical teeth (rarely tricuspid). Border of maxillary relatively straight. Maxilla with 1*(55) or 2(4) tricuspid teeth along anteroventral margin ( Fig. 2 ). Median cusp in all cuspidate teeth longer than remaining cusps; cusp tips slightly curved inwardly in dentary, premaxillary teeth cusps approximately straight.

Scales cycloid, with few radii (3-6), relatively short, at the margin of scale. Lateral line incomplete, slightly curved posteriorly, extending to vertical through distal tip of pectoral fin; perforated scales of lateral line 8(7), 9(7), 10(12), 11(12), 12*(13), 13(4), 14(2), or 15(2); longitudinal scale series including pored scales 29(3), 30(14), 31(19), 32(8), 33*(6), or 34(7); 5*(53) or 5½(6) scale rows between dorsal-fin origin and lateral line; 3½(25) or 4*(34) scale rows between lateral

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line and pelvic fin. Predorsal scales 10(4), 11*(49), or 12(6). Scale sheath along anal-fin base 5(2), 6(11), 7*(22), 8(8), or 9(4) in a single row. Circumpeduncular scales 13(14) or 14*(45). Axillary scale, longer than wide, relatively folded in half, and extending over 1-2 longitudinal scale series.

Dorsal-fin rays ii,8(4) or 9*(55); first unbranched ray approximately half length of second one. Dorsal-fin origin at midbody, at vertical through anterior third of pelvic-fin base, base of last ray at vertical through base of second or third anal-fin branched ray. Tip of longest ray of adpressed dorsal fin at vertical through 8 th to 10 th anal-fin branched ray insertion. First dorsal-fin pterygiophore inserting behind neural spine of 5 th (1) or 6 th (4) vertebra. Adipose fin present. Pectoral fin i,9(14), 10*(36), or 11(9) rays. Pelvic fin i,6(2) or 7*(57) rays. Pelvic-fin origin located anterior to vertical through dorsal-fin origin. Anal-fin rays iii, 15(14), 16(29), or 17*(16). Caudal fin forked, lobes slightly rounded, similar in size, with i,8/8,i(1) or i,9/8,i*(58) rays. Caudal fin scaled, with scales along base of upper and one-third of lower caudal-fin lobe; scales gradually decreasing in size posteriorly ( Fig. 3a ). Dorsal procurrent caudal-fin rays 10(3), 11(2), and ventral procurrent caudal-fin rays 9(1) or 10(4).

Branchiostegal rays 4(5). First gill arch with 6(5) rakers on epibranchial, 1(5) between epibranchial and ceratobranchial, 10(5) in ceratobranchial, and 2(5) on hypobranchial. Precaudal vertebrae 16(5) and caudal vertebrae 17(4) or 18(1). Supraneurals 4(2) or 5(3), thin, not varying in width.

Color in alcohol. Overall body color varying from whitish to pale yellowish. Head dusk to dark brownish dorsally. Region from the posterior portion of second to fifth infraorbital and opercular apparatus silvery on specimens recently collected and yellowish on long time alcohol preservated ones. Small dark melanophores surrounding nare, lips, dorsal margin of maxillary bone, and anterior margin of orbit; larger melanophores scattered over infraorbitals three-six and opercular apparatus. Humeral region with concentration of melanophores occupying two scale rows above and one scale row bellow lateral line, resulting in faint humeral spot. Portion of spot above lateral line two scales wide and one scale wide bellow it. Dorsal and dorso-lateral portions of body with a reticulated pattern due to concentration of melanophores at the posterior margin of the scales. Lateral side of body with scattered melanophores, except at the abdominal region. Longitudinal stripe dark, one-scale wide, and extending from vertical through dorsal-fin origin to caudal-peduncle end, extending onto proximal one-third of middle caudal-fin rays. Lower lateral side of caudal region with few melanophores following the muscles epaxialis and hypaxialis superficial lines.All fins hyaline with scattered melanophores, sometimes bordering the margins of the rays.

Color in life. Overall body and head color pattern reddish in males and yellowish in females. Pattern of melanophores distribution on head, body and fins similar to that described for specimens in alcohol. Proximal two thirds of dorsal, pectoral, pelvic, anal and caudal-fin rays red-orange in males and yellowish in females, except middle caudal-fin rays. Proximal portion of adipose fin and ventral surface of body from the end of pelvic-fin insertion to lower caudal-fin rays origin orange to reddish in males and yellowish in females ( Fig. 4 ) (see also Sexual dimorphism).

Sexual dimorphism. Bony hooks on pelvic and anal-fin ray were observed only in males larger than 23.9 mm SL. Pelvic fin of males bearing small bony hooks along ventromedial border of first to fifth branched rays; one hook per ray segment. Anal fin with small bony hooks situated on distal portion of anal-fin rays, from the last unbranched anal-fin ray to first to eighth branched rays; one hook per ray segment. Males and females also differ in proportions of the pectoral and pelvic fins ( Fig. 5 ), dorsal- and anal-fin base length, and pelvic fin to anal fin distance ( Table 1), and in the anal-fin distal border shape, which is approximately straight on males and slightly concave in the anterior portion in females. Adipose fin located immediately after vertical through last branched anal-fin ray insertions in females and at vertical through last three or four anal-fin ray insertions in males. Tip of longest ray reaching anal-fin origin in males but not in females. Live specimens, or just after fixation, possess body and fins red to orange on males and yellowish in females ( Fig. 4 ). Gill glands (Burns & Weitzman, 1996) were not found on first gill arch on both males and females.

Distribution. Hemigrammus tocantinsi occurs in the tributaries of the rio das Almas, rio Paranã drainage, upper rio Tocantins basin, Goiás State, Brazil ( Fig. 6 ).

Etymology. The specific name tocantinsi is a reference to the rio Tocantins basin, where the new species inhabit. A noun in apposition.

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Ecological notes. The new species lives in streams, occuring in semi-lentic and lotic shallow areas (up to 1 m deep) with riparian vegetation composed by trees and shrubs ( Fig. 7 ). The new species was collected syntopically with Aspidoras albater , Astyanax sp. , Characidium stigmosum , Corumbataia veadeiros , and Trichomycterus sp. Stomach contents of five specimens (UFRGS 11300, 25.1-27.1 mm SL) were mainly composed by Diptera (pupae) and allochthonous insects, but it was also found authochthonous insects and digested vegetal matter in a lesser amount.

Spermatozoa. Hemigrammus tocantinsi has a typical aquasperm with spherical to slightly ovoid nucleus (UFRGS 11300, 25.1 mm SL), suggesting that the species is noninseminating (Burns & Weitzman, 2005) ( Fig. 8 ).

Figures

Fig. 1. Hemigrammus tocantinsi, holotype, male (few days after fixation), MCP 44444, 28.2 mm SL, rio das Pedras, Fazenda Córrego Fundo, municipality of Cavalcante, Goiás State, Brazil.

Fig. 2. Hemigrammus tocantinsi, paratype, female, UFRGS 11300, 27.4 mm SL. Scanning electronic micrograph of lower and upper jaws, left side. Scale bar = 1 mm. Maxillary tooth a little dislocated inwardly.

Fig. 3. Caudal squamation: (a) Hemigrammus tocantinsi, paratype, UFRGS 9907, 27.3 mm SL and (b) Hemigrammus marginatus, MCP 43324, 32.4 mm SL. Scale bars = 1 mm.

Fig. 4. Hemigrammus tocantinsi, paratypes, UFRGS 11300, male above, 27.3 mm SL and female below, 29.5 mm SL. Images of specimens just after fixation.

Fig. 5. Hemigrammus tocantinsi: (a) pectoral-fin length and (b) pelvic-fin length as function of standard length in males and females.

Fig. 6. Geographic distribution of Hemigrammus tocantinsi in rio das Almas drainage, upper rio Tocantins basin, Brazil. Rectangle = municipality of Cavalcante, GO; stars = localities of occurrence of H. tocantinsi; lozenge = type-locality. Arrow shows the direction of rio das Almas flow.

Fig. 7. Type locality of Hemigrammus tocantinsi, Brazil, Goiás, Cavalcante, rio das Pedras, Fazenda Córrego Fundo.

Fig. 8. Hemigrammus tocantinsi, paratype, spermatozeugmata, UFRGS 11300, 25.1 mm SL. Scale bar = 2 µm.