Rivulus rutilicaudus, 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 : 77-80

Rivulus rutilicaudus , new species

Figs. 8 -9

Rivulus pictus (non Costa, 1989). - Costa, 1995a: 216 (misidentification, specimens from Mineiros).

Holotype. UFRJ 5965, male,22.9 mmSL; Brazil: EstadodeGoiás: Município de Serranópolis, rio Verde floodplains, rio Paraná basin, road BR- 060, 18 o 22’31.5”S 52 o 0’59.5”W, altitude 531 m; by W. J. E. M. Costa, B. B. Costa and C. P. Bove, 15 January 2004.

Paratypes. Brazil: Estado de Goiás: rio Verde drainage, rio Paraná basin: UFRJ 5966, 4 males, 15.8-20.9 mm SL, 4 females, 15.4-22.8 mm SL, 3 juveniles of undetermined sex, 11.5-15.1 mm SL ; MCP 36124; 1 male, 16.3 mm SL, 1 female, 15.4 mm SL ; UFRJ 5967 , 2 males, 17.5-17.6 mm SL, 1 female, 18.5 mm SL (c&s); collected with the holotype .

Additional material (non type specimens). UFRJ 2208, 9 ex.; stream tributary to the upper rio Verde drainage, rio Paraná basin, road BR-364, 19 km SE from the city of Mineiros, Município de Mineiros ; W. J. E. M. Costa, A. Sarraf, R. D’Arrigo and G. Carvalho, 16 Sep 1994 .

Diagnosis. Distinguished from its congeners in possessing a dark orangish red caudal fin in females (vs. caudal fin hyaline or pale colored). Also distinguished from all other species of the R. punctatus group by the following combination of features: 10-12 dorsal fin rays (vs. 8-10), 34-35 scales on the longitudinal series (vs. 29-31), dorsal-fin origin at vertical between base of eighth and ninth anal-fin ray (vs. between base of seventh and eighth or ninth and eleventh anal-fin ray), frontal squamation E-patterned (vs. F-patterned), flank with striking iridescent colors in male, contrasting metallic blue to greenish blue on middle of flank with light purplish blue above anal fin and brownish golden on anterior dorsolateral portion of body (vs. never a similar color pattern), flank with narrow pale red chevron-like oblique bars with anteriorly directed vertex (vs. never a similar pattern), and no distinctive dark stripe along midline of flank (vs. stripe present).

Description. Morphometric data in Table 5. Largest specimen 22.9 mm SL, male. Dorsal profile slightly convex from snout to end of dorsal-fin base, approximately straight to slightly concave on caudal peduncle. Ventral profile convex on head, weakly convex from anterior portion of venter to end of analfin base, nearly straight to gently concave along caudal peduncle. Body slender, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at level of pelvic-fin base.

Dorsal and anal fins weakly pointed to rounded in male, rounded in female. Caudal fin almost circular. Pectoral fin rounded, posterior margin on vertical just anterior to pelvicfin base. Tip of pelvic fin reaching urogenital papilla in male, and anus 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 17th and 19th vertebrae. Anal-fin origin between pleural ribs of 13th and 15th vertebrae. Dorsal-fin rays 10-12; anal-fin rays 14-5; caudal-fin rays 32-34; pectoral-fin rays 12-13; pelvic-fin rays 7.

faint red bars. Anal fin pale yellow, base white to pale blue with six short red bars. Caudal fin yellow with four or five red bars on middle. Pelvic fin pale yellow. Pectoral fin yellowish hyaline.

Female: Side of body pale metallic greenish blue, with narrow red chevron-like oblique bars with anteriorly directed vertex; dark red blotch on humeral region. Anterior dorsolateral portion of flank pale golden. Dorsum light brown with gray blotches, venter white. Opercular region pale golden with two oblique dark red bars and blotches. Dark red marks on opercle and anterior portion of flank becoming black when exposed to light. Infraorbital region and ventral surface of head white. Lower jaw reddish gray. Iris light yellow. Dorsal fin dark yellow with three dark gray bars; broad dark gray distal stripe. Anal fin light yellow, base light blue with red dots; broad dark gray distal stripe. Caudal fin dark orangish red with four or five dark gray bars on middle; margins dark gray; black spot on subdorsal portion of caudal fin base. Pelvic fin pale blue, anterior margin dark gray. Pectoral fin hyaline.

Distribution. rio Verde drainage, rio Paraná basin, central Brazil ( Fig. 2 ). Rio Verde here assigned is a right affluent to the rio Paraná, situated between rio Correntes and rio Claro, Estado de Goiás.

Etymology. From the Latin rutilis (bright red, rufous) and caudus (tail), in reference to the diagnostic orangish red caudal fin in females.

Rivulus pictus (non Costa, 1989). - Costa, 1995a: 216 (misidentification, specimens from the rio Sucuruí and rio Aporé drainages).

Holotype. UFRJ 5968, male, 26.8 mm SL; Brazil: Estado de Mato Grosso do Sul: Município de Costa Rica, stream tributary to the upper rio Sucuruí drainage, rio Paraná basin, 18 o 53’54.7”S 52 o 58’44.2”W, altitude 810 m; W. J. E. M. Costa, B. B. Costa and C. P. Bove, 13 Jan 2004.

Paratypes. Brazil: Estado de Mato Grosso do Sul, rio Paraná basin, rio Sucuruí drainage. UFRJ 5969, 8 males, 18.9-28.9 mm SL, 11 females, 17.9-31.5 mm SL; MCP 36125, 2 males, 20.5- 20.9 mm SL, 3 females, 22.0- 23.9 mm SL; UFRJ 5970, 2 males, 22.4-22.6 mm SL, 2 females, 19.2-24.6 mm SL; with the holotype. UFRJ 2277, 3 males, 20.6-25.6, 2 females, 22.3-26.5; UFRJ 2278, 2 males, 22.6-24.3, 2 females, 23.5-23.9 (c&s); Ribeirão São Luiz, road MS-306; G. C . Brasil and M. T. C. Lacerda, 22 Jan 1988 .

Additional material (non type specimens). Brazil: Estado de Mato Grosso do Sul, rio Paraná basin, rio Aporé drainage: UFRJ 2209, 17 ex.; stream tributary to rio Aporé, 68 km NW from Cassilândia ; W. J. E. M. Costa, A. Sarraf, R. D’Arrigo and G. Carvalho, 17 Sep 1994 . UFRJ 2276, 10 ex.; road between Paranaíba and Cassilândia ; G. C. Brasil and M. T. C. Lacerda, 21 Jan 1988 . UFRJ 2207, 20 ex.; UFRJ 2280, 3 ex. (c&s); swamp close to ribeirão Grande, road MS-306, 29 km SE from the city of Cassilândia, Município de Cassilândia; W. J. E. M. Costa, A. Sarraf , R. D’Arrigo and G. Carvalho, 17 Sep 1994 . Estado de Goiás, rio Paraná basin, rio Correntes drainage: UFRJ 5387, 2 ex.; upper section of rio Formoso ; W. J. E. M. Costa, S. M. Lima and A. C. Bacellar, 31 Mar 1999 . Estado de Mato Grosso: MZUSP 73354 , 15 ex.; stream tributary to rio Taquari, rio Paraguay basin, km 421.07 of the Ferronorte railway; C. L. R. Moreira and F. C. T. Lima, 22 May 2001 .

Diagnosis. Differs from all other species of the R. punctatus group by the color pattern of adult males, consisting of flank intense metallic blue with small red squares aligned to form broad red chevron-like oblique bars (vs. never a similar color pattern). It may be also distinguished from other species of

the R. punctatus group by the combination of the following features: 10-12 dorsal fin rays (vs. 8-10), 32-34 scales on the longitudinal series (vs. 29-31), frontal squamation E-patterned (vs. F-patterned), 29-31 vertebrae (vs. 31-33), dorsal-fin origin at vertical between base of seventh and eighth anal-fin ray (vs. between base of eighth and eleventh ray), flank with intense iridescent colors in male, contrasting metallic blue to greenish blue on middle of flank with light purplish blue above anal fin and brownish golden on anterior dorsolateral portion of body (vs. never a similar color pattern), and no distinctive dark stripe along midline of flank (vs. stripe present).

Description. Morphometric data in Table 6. Largest specimen 31.5 mm SL, female. Dorsal profile slightly convex from snout to end of dorsal-fin base, approximately straight to slightly concave 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, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at level of pelvic-fin base.

Dorsal and anal fins slightly pointed in male, rounded in female. Caudal fin rounded, almost circular. Pectoral fin rounded, posterior margin on vertical just anterior to pelvicfin base. Tip of pelvic fin reaching between base of 1st and 3rd anal-fin ray in male, and anus in female. Pelvic-fin bases in close proximity. Dorsal-fin origin on vertical through base of 7th or 8th anal-fin ray, and between neural spines of 18th and 20th vertebrae. Anal-fin origin between pleural ribs of 13th and 16th vertebrae. Dorsal-fin rays 10-12; anal-fin rays 12-14; caudal-fin rays 31-33; pectoral-fin rays 12-13; pelvicfin rays 7.

Scales large, cycloid. Trunk scaled; head scaled except on its anteroventral surface. Body scales slightly extending over caudal-fin base; no scales on dorsal and anal fins. Frontal squamation E-patterned; E-scales not overlapping medially; scales arranged in circular pattern around central A-scale without exposed margins. Longitudinal series of scales 32- 34; 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. Two vomerine teeth. Total vertebrae 29-31.

Coloration. Male: Side of body intense metallic blue to metallic greenish blue anteriorly and purplish blue ventrally, with broad red chevron-like oblique bars with anteriorly directed vertex, sometimes with red spots and vertical red lines between oblique bars; dark red spots on humeral region. Chevron-like bars of flank formed by small aligned square spots, resulting in indented posterior margin of bars in larger specimens. Anterior dorsolateral portion of flank light brownish golden. Dorsum light yellowish brown, venter white. Opercular region golden with two oblique dark red bars. Opercular and humeral red marks becoming black when exposed to light. Infraorbital region and ventral surface of head white. Lower jaw gray. Iris light yellow, anterior and posterior portion dark brown. Dorsal fin yellow with four faint red bars. Anal fin bright yellow, base pale blue with six short red bars. Caudal fin yellow with five to seven narrow pale red bars. Pelvic fin bright yellow. Pectoral fin yellowish hyaline.

Female: Side of body pale metallic greenish blue, with red chevron-like oblique bars with anteriorly directed vertex; small dark red blotch on humeral region. Anterior dorsolateral portion of flank pale golden. Dorsum light brown with pale gray dots, venter white. Opercular region pale golden with two oblique dark red bars. Dark red marks on opercle and anterior portion of flank becoming black when exposed to light. Infraorbital region and ventral surface of head white. Lower jaw gray. Iris light yellow. Dorsal fin pale yellow with two dark gray bars; dark gray distal stripe.Anal fin light yellow, base light blue with red dots; dark gray distal stripe. Caudal fin pale yellow with three to six gray bars; margins dark gray; black spot on subdorsal portion of caudal fin base. Pelvic fin pale yellow, anterior margin gray. Pectoral fin hyaline.

Distribution. rio Sucuruí, rio Aporé and upper rio Correntes drainages, rio Paraná basin, and upper rio Taquari drainage, rio Paraguay basin, central Brazil ( Fig. 2 ).

Etymology. From the Latin scalaris (with a stair), referring to the color pattern of males consisting of red oblique bars with indented posterior borders, resembling small squares aligned to form stairs.

Figures

Fig. 8. Rivulus rutilicaudus, UFRJ 5965, male, holotype, 22.9 mm SL (one day after collection); Brazil: Goiás: Serranópolis. Photo by W. J. E. M. Costa.

Fig. 2. Geographic distribution of species of the genus Rivulus in the Paraná, Paraguay, and upper Araguaia river basins, central Brazil.