Rivulus dapazi, Costa, 2005

Costa, Wilson J. E. M., 2005, Seven new species of the killifish genus Rivulus (Cyprinodontiformes: Rivulidae) from the Paraná, Paraguay and upper Araguaia river basins, central Brazil, Neotropical Ichthyology 3 (1), pp. 69-82 : 71-72

Rivulus dapazi , new species

Fig. 1

Holotype. UFRJ 5915, male, 24.3 mm SL; Brazil: Estado de Mato Grosso do Sul: Sonora, córrego Confusão, tributary to rio Correntes , rio Paraguay basin, 17 o 33’56.4”S 54 o 44’23.8”W, altitude 411m; W.J.E.M.Costa, C. P.Bove & B. B. Costa, 22 Jul2003 . Paratypes. Brazil: Estado de Mato Grosso do Sul: Sonora : rio Paraguay basin: UFRJ 5916, 3 females, 21.9-22.8 mm SL; UFRJ 5917, 1 male, 20.7 mm SL, 1 female, 18.7 mm SL (c&s); collected with the holotype. UFRJ 5918, 5 males, 20.9-31.7 mm SL, 3 females, 20.9-24.9 mm SL; UFRJ 5919, 2 males, 21.9-24.1

mm SL (c&s); córrego do Burro , tributary to rio Correntes; R. C. da Paz, 6 Feb 2003 . Estado de Mato Grosso : Itiquira: rio Paraguay basin. UFRJ 5920, 7 males, 14.2-22.1 mm SL, 5 females, 13.5-21.6 mm SL; UFRJ 5921, 2 males, 23.0- 26.7 mm SL, 1 female, 19.1 mm SL (c&s); rio Comprido, a tributary to rio Correntes; R. C. da Paz, 5 Feb 2003 . UFRJ 5922, 1 female, 21.4 mm SL; right bank of rio Correntes ; R. C. da Paz, 4 Feb 2003 . MCP 36120, 5 males, 16.6-19.1 mm SL, 4 females, 15.6-21.5 mm SL; right bank of rio Comprido , a tributary to rio Correntes; R. C. da Paz, 4 Feb 2003 . UFRJ 5924, 2 males, 19.1-20.5 mm SL, 1 female, 22.0 mm SL; rio Comprido ; R. C. da Paz, 6 Feb 2003 .

Diagnosis. Distinguished from all other species of the R. punctatus group in having an anal fin with an orange distal stripe (vs. orange distal stripe absent) and caudal fin with marginal region dark orange with black ventral outline in males (vs. never a similar pattern). Differs from all other species from the Paraná-Paraguay basin by the combination of the following features: flank with chevron-like red lines (vs. oblique rows of red dots), flank with dark gray stripe along midline (vs. stripe absent), and 34-35 scales on the longitudinal series (vs. 30-32 as in all other species of the rio Paraguay basin).

Description. Morphometric data in Table 1. Largest specimen 31.7 mm SL, male. Dorsal profile slightly convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile convex on head, almost straight from anterior portion of venter to end of anal-fin base, nearly straight along caudal peduncle. Body slender, approximately cylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at level of pelvic-fin base.

Dorsal and anal fins rounded. Caudal fin oval. Pectoral fin rounded, posterior margin on vertical just anterior to pelvicfin base. Tip of pelvic fin reaching between urogenital papilla and base of first anal-fin ray in male, and urogenital opening in female. Pelvic-fin bases in close proximity. Dorsal-fin origin on vertical through base of 8th or 9th anal-fin ray, and between neural spines of 18th and 19th vertebrae. Anal-fin origin between pleural ribs of 13th and 15th vertebrae. Dorsalfin rays 10-11; anal-fin rays 14-15; caudal-fin rays 30-31; pectoral-fin rays 13-14; pelvic-fin rays 6-7.

Scales large, cycloid. Trunk scaled; head scaled except on anteroventral surface. Body scales slightly extending over caudal-fin base; no scales on dorsal and anal fins. Frontal squamation usually F-patterned, sometimes E-patterned; Escales not overlapping medially; scales arranged in circular pattern around central A-scale without exposed margins. Longitudinal series of scales 34-35; transverse series of scales 8; scale rows around caudal peduncle 16. Contact organs absent. Supraorbital neuromasts 3 + 3. Six branchiostegal rays. Gill rakers of first branchial arch 1 + 7-8. One to three vomerine teeth. Total vertebrae 30-31.

Figures

Fig. 1. Rivulus dapazi, UFRJ 5915, male, holotype, 24.3 mm SL (minutes after collection); Brazil: Mato Grosso do Sul: Sonora. Photo by W. J. E. M. Costa.