Moenkhausia dasalmas, Bertaco & Jerep & Carvalho, 2011

Bertaco, Vinicius A., Jerep, Fernando C. & Carvalho, Fernando R., 2011, New species of Moenkhausia Eigenmann (Ostariophysi: Characidae) from the upper rio Tocantins basin in Central Brazil, Neotropical Ichthyology 9 (1), pp. 57-63 : 58-60

Moenkhausia dasalmas , new species

Figs. 1-5

Holotype. UFRGS 11221 , 1 , 42.9 mm SL, Brazil, Goiás, Cavalcante , tributary of the rio das Almas about 8 km North of Cavalcante on GO 241 road, upper rio Tocantins basin, between Cavalcante and Minaçu, 13º43’13’’S 47º27’20’’W, 8 Sep 2009, V.A. Bertaco, F. C. Jerep & F. R. Carvalho.

Paratypes. Brazil, Goiás, Cavalcante , upper rio Tocantins basin. UFRGS 11194 , 24 (10; 3 c&s), 20.5-35.8 mm SL, MCP 45679, 10 (5), 23.0- 30.5 mm SL, MZUSP 106076 , 8 (2), 22.3-32.9 mm SL, córrego Grotão or Rita Maria about 4 km North of Cavalcante on GO 241 road, between Cavalcante and Minaçu, 13º45’18’’S 47º27’20’’W, 6 Sep 2009, V. A. Bertaco, F. R. Carvalho & G. L. C. Frainer. UFRGS 11589 , 4 (4), 21.5-31.0 mm SL, same locality of UFRGS 11194 , 25 May 2008, F. C. Jerep & T. P. Carvalho .

Diagnosis. Moenkhausia dasalmas is distinguished from all congeners by the presence of iii,9 rays in the dorsal-fin, Fig. 2 (vs. ii,9). Additionally, M. dasalmas can be distinguished from most congeners by the presence of two humeral spots, in which the first one is vertically elongate (except from M. diamantina Benine, Castro & Santos , M. diktyota Lima & Toledo-Piza, M. eigenmanni Géry , M. georgiae Géry , M. inrai Géry , M. levidorsa Benine , M. moisae Géry, Planquette & Le Bail , M. naponis Böhlke , M. pankilopteryx Bertaco & Lucinda , and M. surinamensis Géry ) (vs. absent, or horizontally elongate or diffuse humeral spot). Moenkhausia dasalmas differs from the remaining species by the number of branched anal-fin rays (17-19 vs. 20-35). It can be further distinguished from M. diktyota , M. eigenmanni , M. georgiae , M. inrai , M. levidorsa , M. moisae , and M. naponis by the number of the lateral line scales (36-37 vs. 41-47 in M. moisae , and 31-35 in the remaining species), and from M. pankilopteryx by the number of maxillary teeth (4-5 vs. 2-3) and the shape of the caudal peduncle spot (vertically elongate vs. horizontally elongate in M. pankilopteryx ).

Description. Morphometric data summarized in Table 1. Body compressed, moderately short, greatest body depth usually located anterior to 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 straight to slightly concave.

Mouth terminal, jaw isognathous. Maxilla extending posteroventrally to vertical through anterior half of orbit, aligned approximately at 45 degree angle relative to longitudinal axis of body. Maxilla slightly widened anteroposteriorly.

Two tooth rows in the premaxilla: outer row with three* to four tri- to pentacuspid teeth (mode = 3, n = 22), central cusp longer; inner row with five teeth, gradually decreasing in length from first to fourth, last distinctly smaller, with five to seven cusps; central cusp twice as long and broad as others cusps. Maxilla with four to five* teeth (mode = 4, n = 22), three to five cusps, with central cusp slightly longer. Four anteriormost dentary teeth larger, with five or seven cusps, followed by one medium-sized tooth with five cusps, and five or seven teeth with one to three cusps. Central cusp in all teeth two to three times as long and broad as other cusps. All cusp tips slightly curved posteriorly towards inside mouth ( Fig. 3 ).

Dorsal-fin rays iii,9* (n = 22); first unbranched ray approximately one-fifth to one-seventh of second unbranched ray, which is approximately half-length of third unbranched ray. First branched rays longest. Distal margin of dorsal fin nearly straight to somewhat convex. Adipose fin origin approximately at vertical through last anal-fin ray insertion. Anal-fin rays iv-v,17-19 (iv,18*, mode = iv,18, n = 22). First unbranched ray usually apparent only in c&s specimens. Distal profile of anal fin distal profile smoothly concave in the specimens smaller than 34.0 mm SL, and concave in the specimens larger than 34.9 mm SL. Anal fin origin posterior to vertical through base of last dorsal-fin ray. Pectoral-fin rays i,12-13* (mode = 12, n = 22). Pelvic-fin rays i,7* (n = 22). Pelvic-fin origin slightly anterior to vertical through dorsalfin origin. Tip of pelvic fin trespassing genital opening but not reaching anal-fin origin. Caudal fin forked, lobes similar in size, 19* principal rays (n = 22). Dorsal and ventral procurrent caudal-fin rays 12-13 and 11-12, respectively (n = 3).

Lateral line complete, with 36-37* perforated scales (mode = 37, n = 19). Scale rows between dorsal-fin origin and lateral line 7-8* (mode = 7, n = 22); scale rows between lateral line

V. A. Bertaco, F. C. Jerep & F. R. Carvalho 59

and pelvic-fin origin 6-7* (mode = 7, n = 22). Predorsal scales 13-14* (mode = 13, n = 16) arranged in regular series. Scale rows around caudal peduncle 16-18* (mode = 16, n = 16). Axillary scale on pelvic fin origin covering 1-2 scales posteriorly. Scale sheath along anal-fin base 7-10 scales (9*, mode = 8, n = 19), in single series, covering base of anteriormost rays. Caudal fin scaled, scales over base of upper and along first third of lower caudal-fin lobes; scales gradually decreasing in size posteriorly.

Infraorbitals bones 5 (n = 22), fourth and/or fifth absent or fused ( Fig. 4). Precaudal vertebrae 17; caudal vertebrae 18; total vertebrae 35 (n = 3). Supraneurals 5 (n = 3). Branchiostegal rays 4 (n = 3). First gill arch with six rakers on epibranchial, one between epibranchial and ceratobranchial, eight in ceratobranchial, and two on hypobranchial (n = 3).

Color in alcohol. Overall ground color of body varying from whitish to dark yellowish ( Figs. 1 and 5 ). Dorsal portion of snout, head and body darker than remaining regions. Small melanophores scattered all over head and body, including abdominal region. Larger melanophores scattered over orbital series and opercular apparatus. Scales of longitudinal rows above lateral line series with reticulated color pattern, due to higher concentration of melanophores on their distal margin. Specimens larger than 35.0 mm SL also with a reticulated pattern on most anterior scales of longitudinal rows bellow lateral line series. Two vertically elongate humeral spots, separated by a less pigmented, but not completely pale area. First humeral spot conspicuous, three to four scales wide, narrowing ventrally, and vertically extending over four longitudinal scale rows above lateral line series, and three longitudinal scale rows bellow it. Second humeral spot diffuse, not as dense pigmented as first one, two to three scales wide, fainting posteriorly and ventrally, and extending vertically over four longitudinal scale rows above lateral line series, and at most one longitudinal scale row bellow it. Longitudinal stripe brownish, thinner than scales depth or absent, generally with a denser amount of scattered melanophores along its length. Longitudinal stripe, when present, extending from second humeral spot and contacting caudal peduncle spot on larger specimens, or falling short vertical through adiposefin insertion on smaller. Chevron-shaped striae (chevronshaped bars) posteriorly diverging from longitudinal line, following mioseptum lines, more evident on specimens with longitudinal line not well pigmented ( Fig. 5 ). Caudal peduncle spot faint and vertically expanded, sometimes overlapping base of caudal-fin rays, reaching at most six longitudinal scale lines on larger specimens, but not reaching dorsal and ventral margins of caudal peduncle. All fins hyaline with some melanophores scattered along interradial membranes.Adipose fin hyaline, rarely with dispersed melanophores.

Ta b l e 1. M o r p h o m e t r i c d a t a f o r h o l o t y p e a n d 1 5 paratypes of Moenkhausia dasalmas from the upper rio Tocantins basin. The range includes the holotype. SD = Standard deviation .

syntopically with Aspidoras albater Nijssen & Isbrücker , Astyanax sp. , Characidium stigmosum Melo & Buckup , Corumbataia veadeiros Carvalho , Hemigrammus tocantinsi Carvalho, Bertaco & Jerep , and Trichomycterus sp. Stomach contents of three specimens (UFRGS 11194, 24.4-27.3 mm SL) were mainly composed by Hymenoptera, Coleoptera (adults) and some fish scales, but autochthonous insects and digested vegetal organic matter (seeds) was also found.

Sexual dimorphism. Secondary sexual characters were not found on examined specimens. Immature gonads were observed in one dissected and c&s specimen (UFRGS 11194, 27.3mmSL).

Distribution. Moenkhausia dasalmas is known from tributaries of the rio das Almas, rio Paranã drainage, upper rio Tocantins basin, in the Chapada dos Veadeiros region, Brazilian Cerrado, Goiás, Brazil.

Etymology. The name dasalmas is a reference to the occurrence in the rio das Almas basin, where the new species inhabit. A noun in apposition.

Ecological notes. The collection locality is around 800 m above sea level. Moenkhausia dasalmas inhabits streams, and occurs in semi-lentic and lotic shallow areas (up to 1.0 m deep) with riparian vegetation composed by trees and shrubs ( Fig. 6 ). The streams have transparent water, and bottom with rocks, stones, and some stretches with sand. The new species was collected

Figures

Fig. 1. Moenkhausia dasalmas, holotype, UFRGS 11221, 42.9 mm SL, tributary of rio das Almas, Cavalcante, Goiás, Brazil.

Fig. 2. Left lateral view of the dorsal fin of Moenkhausia dasalmas, paratype, UFRGS 11194, 23.3 mm SL, c&s; showing the unbranched and branched rays. Scale bar = 1 mm.

Fig. 3. Drawing of upper and lower jaws; left lateral view. Moenkhausia dasalmas, paratype, UFRGS 11194, 27.3 mm SL. Scale bar = 1 mm.

Fig. 5. Moenkhausia dasalmas, paratype, UFRGS 11194, 28.6 mm SL, tributary of rio das Almas, Cavalcante, Goiás, Brazil.

Fig. 6. Type locality of Moenkhausia dasalmas, tributary of rio das Almas, Cavalcante, Goiás, Brazil.