Simpsonichthys cholopteryx

Wilson J. E. M. Costa, 2007, Taxonomic revision of the seasonal South American killifish genus Simpsonichthys (Teleostei: Cyprinodontiformes: Aplocheiloidei: Rivulidae)., Zootaxa 1669, pp. 1-134 : 26-29

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Simpsonichthys cholopteryx


Simpsonichthys cholopteryx   ZBK Costa, Moreira & Lima, 2003

(Figs. 13-14)

Simpsonichthys cholopteryx   ZBK Costa, Moreira & Lima, 2003: 140 ( type locality: ribeirao do Sapo, rio Araguaia basin, on road MT 100, 31 km S of Alto Araguaia , Estado de Mato Grosso, Brazil, 17°33’38.5”S 53°18’33.1”W; holotype: MZUSP 78061 GoogleMaps ).

Material examined

Brazil: Estado de Mato Grosso: Município de Alto Araguaia, upper rio Araguaia drainage, rio Amazonas basin: MZUSP 78061 , holotype, male, 23.5 mm SL; UFRJ 5428 , 29 paratypes; Ribeirao do Sapo on road MT 100, 31 km S of Alto Araguaia , 17°33’38.5”S 53°18’33.1”W; W. J. E. M. Costa, S. M. Q. Lima, D. F. Belote & E. S. Araujo, 6 Apr. 2002. GoogleMaps MZUSP 73338 , 16 paratypes (6 c&s); Ribeirao do Sapo, km 464 of Ferronorte railway , 17°31’11”S 53°15’33”W; C. L. R. Moreira & F. C. T. Lima, 21 May 2001. GoogleMaps MZUSP 73323 , 41 paratypes; Corrego do Sapinho, km 474 of Ferronorte railway (17°25’55”S 53°14’34”W); C. L. R. Moreira & F. C. T. Lima, 19 May 2001. GoogleMaps


Distinguished from all other congeners by the combination of the following features: absence of pelvic fins and pelvic girdle (vs. presence); dorsal-fin origin posterior (vs. anterior) to anal-fin origin, 16-18 dorsalfin rays in males (vs. 19-22), 20-23 anal-fin rays in males (vs. 17-19), 20-22 anal-fin rays in females (vs. 17- 20), maximum adult size 23.5 mm SL (vs. 40.0 mm SL), distal border of both dorsal and anal fins dark gray in males (vs. dark red), posterior border of caudal fin dark gray in males (vs. pale pink), iridescent dots on unpaired fins absent in males (vs. present), pectoral fins hyaline in males (vs. red)), with metallic blue spots in males; iris blue in males (vs. yellow), iridescent blue bars on flank approximately as wide as red bars in males (vs. much narrower), ground color of dorsal and anal fins light blue anteriorly, yellow posteriorly in males (vs. whole fins orange), and presence of dark bars on unpaired fins in males (vs. bars absent).


Morphometric data appear in Table 2. Largest specimen examined 23.5 mm SL. Dorsal profile convex from snout to end of dorsal-fin base, nearly straight on caudal peduncle. Ventral profile convex from lower jaw to end of anal-fin base, approximately straight on caudal peduncle. Body moderately deep, compressed, greatest body depth at point just anterior to anal-fin base. Eye positioned on dorsal portion of head side. Snout blunt. Urogenital papilla cylindrical and short in males, pocket-shaped in females.

Tip of both dorsal and anal fins pointed in males, rounded in females; filamentous rays absent. Dorsal-fin rays unbranched. Caudal fin rounded. Pectoral fins elliptical. Posterior margin of each pectoral fin reaching vertical through base of third or fourth anal-fin ray in males, and vertical just anterior to anus in females. Pelvic fins and pelvic girdle absent. Dorsal-fin origin on vertical through base of 5th anal-fin ray in males, and 2nd anal-fin ray in females; dorsal-fin origin between neural spines of vertebrae 9-11 in males, and vertebrae 10-12 in females. Anal-fin origin between pleural ribs of vertebrae 7-10 in males, and vertebrae 9-10 in females. Dorsal-fin rays 17-18 in males, 15-17 in females; anal-fin rays 20-23 in males, 20-22 in females; caudal-fin rays 23-25; pectoral-fin rays 13.

Frontal squamation E-patterned; E-scales medially overlapped; no scale anterior to G-scale; one supraorbital scale. Longitudinal series of scales 22-24; transverse series of scales 8-10; scale rows around caudal peduncle 14-16. Minute contact organ on each scale of ventral portion of lateral surface of body in males. No contact organs on pectoral-fins.

Cephalic neuromasts: supraorbital 2 + 5-7, parietal 2, anterior rostral 1, posterior rostral 1, infraorbital 1 + 11-14, preorbital 2, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1, preopercular 7, mandibular 4, lateral mandibular 2, paramandibular 1. One neuromast on center of each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, width about 30% of length; basihyal cartilage about 20% of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth absent. Gill-rakers on first branchial arch 2 + 8. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal absent. Total vertebrae 24-26.


Males. Body and head pale brown; flanks with 10-11 dark red bars alternating with iridescent dark blue bars; sides of head with four dark red bars, one below eye and three on opercular region, alternating with four light blue bars. Iris greenish blue, with dark reddish brown bar. Dorsal fin yellow, light blue on anterior portion, with six to seven pale brown bars; distal dark gray stripe, ventrally bordered by metallic green line. Anal fin light blue on anterior and yellow on posterior half, with six pale brown bars; distal dark gray stripe, dorsally bordered by metallic blue line. Caudal fin yellow, with four to five brown bars; dark gray band along distal margin, proximally bordered by faint iridescent green line. Pectoral fins hyaline.

Females. Sides of body pale brownish yellow, with 11 dark gray bars; two or three black blotches on anterocentral portion of flank. Sides of head pale brownish yellow, with pale green iridescence on opercular region, and with dark brown bars, three on opercular region, one adjacent to posterior edge of eye, and one on suborbital region. Unpaired fins hyaline, with dark gray spots; anterior portion of anal fin pale orange. Pectoral fins hyaline.


Upper rio Araguaia basin, Estado de Mato Grosso, central Brazil (Fig. 1).


Temporary pools between Campo Úmido and Buritizal in the Cerrado.