Odontesthes bicudo, Malabarba & Dyer, 2002

Malabarba, Luiz R. & Dyer, Brian S., 2002, Description of three new species of the genus Odontesthes from the rio Tramandaí drainage, Brazil (Atheriniformes: Atherinopsidae), Ichthyol. Explor. Freshwaters 13, No. 3, pp. 257-272 : 264-266

Odontesthes bicudo , new species ( Fig. 3 )

Holotype. MCP 26153 , 158 mm SL; Brazil: Rio Grande do Sul: lagoa Emboaba , Osorio (29°57'57"S 50°13'45"W); 7 Oct 1998; L. R. Malabarba, B. Dyer, L. Beheregaray, F. Becker & V. Bertaco .

Paratypes. AH from Brazil: Rio Grande do Sul: rio Tramandaí drainage : MCP 21402 , 26, 120.0­ 205.2 mm SL; same locality as holotype; Aug-Oct 1989. - MCP 21401, 1 , 208 mm SL; same locality as the holotype; 17- 18 Jun 1989; C. B. Fialho, S. Hartz & W. Bruschi. - MCP 21399 , 14, 110.4- 174.9 mm SL; lagoa Caconde , Osorio; 7 Nov 1991; L. R. Malabarba, W. Bruschi & C. E. Giintzel . - MCP 21404 , 5, 149.1 - 174.8 mm SL; lagoa do Horacio , Osorio; 26-27 Nov 1991; W. Bruschi & J. F. Pezzi da Silva. - MCP 21398 , 14, 125.1 - 188.6 mm SL; lagoa do Lessa .

Diagnosis. See discussion.

Description. Morphometric data aresummarized in Table 1 . Body fusiform and elongate; greatest body depth usually near to pelvic-fin origin. Dorsal and ventral body profiles gently convex. Caudal peduncle slender.

Head relatively large. Ventral head profile nearly straight, sometimes with slight convexity at the retroarticuiar joint. Eyes clearly smaller than, snout length. Snout elongated, pointed, in lateral and dorsal views. Mouth terminal; mouth gape horizontal in lateral view; usually larger than eye diameter in specimens larger than 100 mm SL. Mouth gape positioned in an horizontal line crossing near center of eye's pupil and middle of head depth. Two tooth rows in dentary and premaxilla; teeth of inner row twice longer than teeth of external series.

Pectoral-fin rays i, 11-13 (i, 12; mean = 11.8, n = 16). Pectoral fin reaching near to vertical line projected through pelvic-fin origin in specimens up to nearly 150 mm SL, becoming progressively distant from pelvic-fin origin in larger specimens. Pelvic fin with 1 spine and 5 rays (I, 5; n = 16); pelvic fins united medially. Distance from pelvic-fin origin to anal-fin origin twice or more pelvic-fin length.

First dorsal fin I I I-VI (V; mean = 4.53, n- 16); first dorsal-fin origin anterior or above vertical line projected through anal-fin origin. Second dorsal fin with 1 spine and 8-10 rays (1, 9; mean = 8,83, n = 16); second dorsal fin above anal-fin base. Distance from tip of first dorsal fin to second dorsal-fin origin nearly equal to first dor ­ sal-fin length, when fin is depressed. Anal fin with one spine and 15-18 rays (1,16; mean = 16.5; n = 16). Anal-fin profile concave. Caudal fin forked; principal caudal-fin rays i, 15, i.

Scales cycloid. Scales in lateral linescries above lateral band 48-52 (52; mean = 49.9; n = 16). Longitudinal rows of scales between second dorsal fin and anal fin, 8. Predorsal scales 23-26 (25; mean = 25.2, n = 16). Scales between first and sec ­ ond dorsal-fin origins 9-11 (9; mean = 10.1, n = 16). Longitudinal scale rows around caudal peduncle 14- 16 (16; mean = 15.7, n = 16).

Lower branch gill rakers 26-30 (29; mean = 28.1, n = 16); total gill rakers 32-37 (34; mean = 35.1, n = 16). Vertebrae 47(2), 48 (4), 49(3).

Color in alcohol. Black lateral band along sides of body extends from pectoral-fin origin to caudal-fin base, wider above anal-fin base. Lateral band silvery in specimens whose guanine pigment was not destroyed by formalin. Scale borders densely pigmented with dark chromatophores above lateral band, giving dorsal part of body a dark brown reticulate pattern; scale bor ­ ders below lateral band weakly pigmented with dark chromatophores. Abdomen and sides ventral to lateral band pale cream color or yellowish. Fins without distinctive marks, except for first dorsal fin black pigmented and second dorsal fin densely black pigmented along base. Head pigmented dark brown dorsally; pigmented black in dorsal border of maxilla and snout. Head pale cream color or yellowish in lateral and ventral view. Cheek scales usually well delineated by a thin line of dark chromatophores.

Color in life. See Figure 3 of a specimen taken immediately after capture. Livecolor pattern very much like those in preservative. Lateral body band silvery gold. Scale borders above lateral band alsodensely pigmented with dark chromatophores, giving a reticulate pattern over an olive green background color; scale borders below lateral stripe weakly pigmented with dark chromatophores. Abdomen and sides ventral to lateral band white or silvery. Fins without distinctive marks, except for first dorsal fin black pigmented and second dorsal fin densely black pigmented along its base. Head dark green olive dorsally; dark black pigmented in dorsal border of maxilla and snout. Head white to silvery in lateral and ventral view, except fur a golden region in opercle aligned with eyes and lateral body stripe. Iria golden yellow. Cheek scales delineated by a thin line of dark chromatophores.

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Distribution. 01101119511165 liiczido is found in a group of partially isolated freshwater lakes Northeast of the city of Osorio, near the center of the studied area, namely lagoa Ernboaba, lagoa Caconde, lagoa do Horacio, and lagoa do Lessa (Fig. l). Most ot these lakes remain isolated from the rest of the drainage, temporarily connected by shallow streams. There are no Collections availf able from other isolated lakes near or between lagoa Emboaba and lagoa do Lessa, namely lagoa Ernboabiiwha, lagoa Bigua, lagoa do Inácio, lagoa do Rincão, lagoa das Pombas, lagoa das Traíras and lagoa da Caieira, and consequently no information available on the species of Odmitesthvs occurring in them. Odontesfltes birmin has not been found elsewhere. Sympatry with other Otioutrstlres species has been detected only xvith O. prqrznrn (MCP 16364) in the lagoa Caconde.

Etymology. The species name bicudo is a Porto guese word meaning pointed, with a beak, and alludes to the snout shape of this species.

Ecological notes. This species is found in exclusively freshwater lakes of the coastal lagunax' svstem, being absent in the estuarine area of the rio Tramandaí drainage.

Figures

Fig. 3. Odontesthes bicudo, holotype, MCP 26153, 158 mm SL; Brazil, lagoa Emboaba. a, left view; b, head, left view; c, head, dorsal view