Simpsonichthys parallelus

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 : 29-31

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Simpsonichthys parallelus


Simpsonichthys parallelus   ZBK Costa, 2000

(Figs. 15-16)

Simpsonichthys parallelus   ZBK Costa, 2000: 13 (original description; type locality: seasonal swamp in floodplains of rio Formoso, a tributary of rio Correntes, rio Paranaiba drainage, rio Parana basin, Parque Nacional da Emas , Estado de Goiás, Brazil [approximately 22°45’ S, 42°00’ W]; holotype: MZUSP 57537 GoogleMaps ).

Material examined

Brazil: Estado de Goiás, rio Paranaíba drainage, rio Paraná basin: MZUSP 57537 , holotype, male, 22.1 mm SL; MZUSP 57538 , 4 paratypes; UFRJ 4838 , 7 paratypes; UFRJ 4839 , 4 paratypes (c&s); MCP 22681 , 4 paratypes; UFRJ 5196 , 16 paratypes; UFRJ 5197 , 4 paratypes; UFRJ 5386 , 11; seasonal swamp in the floodplains of the rio Formoso, Parque Nacional da Emas ; W. J. E. M. Costa, A. C. Bacellar and S. M. Q. Lima, 31 Mar. 1999. MNRJ 18285 , 5; rio Formoso, Santa Amelia farm, Chapadao do Ceu ; M. R. S. Melo, 11 Oct. 1998.


Distinguished from all 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 dorsal-fin rays in males (vs. 19-22), 20-23 anal-fin rays in males (vs. 17-19), 17-20 anal-fin rays in females (vs. 20-22), distal border of 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), iris blue in males (vs. yellow), iridescent blue bars on flank much narrower than red bars in males (vs. approximately as wide as red bars), ground color of dorsal and anal fins orange in males (vs. light blue anteriorly, yellow posteriorly), dark bars on unpaired fins absent in males (vs. bars present), black spots on posterobasal portion of dorsal fin absent in males (vs. present); yellow dots on caudal fin absent in males (vs. present); maximum adult size 23.5 mm SL (vs. 40.0 mm SL).


Morphometric data appear in Table 2. Largest specimen examined 22.6 mm SL. Dorsal profile convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile convex from lower jaw to end of anal-fin base, nearly straight on caudal peduncle. Body moderately deep, compressed, greatest body depth in vertical just anterior to anal-fin origin. Eye positioned on dorsal portion of each side of head. Snout blunt. Urogenital papilla cylindrical and short in males, pocket-shaped in females.

Tip of dorsal and anal fins gently pointed in males, rounded in females; filamentous rays absent. Dorsalfin rays unbranched. Caudal fin elliptical. Pectoral fins elliptical. Posterior margin of each pectoral fin reaching vertical between base of 2nd and 4th anal-fin rays in males, and between anus and urogenital papilla in females. Pelvic fins and pelvic girdle absent. Dorsal-fin origin on vertical through base of 2nd and 4th anal-fin ray in males, and on vertical through anal-fin origin in females; dorsal-fin origin between neural spines of vertebrae9 and 10 in males and vertebrae 10 and 12 in females. Anal-fin origin between pleural ribs of vertebrae 8 and 9 in males and vertebrae 9 and 10 in females. Dorsal-fin rays 16-18 in males, 15-17 in females; analfin rays 20-22 in males, 17-20 in females; caudal-fin rays 25-27; pectoral-fin rays 13.

Frontal squamation E-patterned; E-scales medially overlapping; no scale anterior to H-scale. Supraorbital scales absent. Longitudinal series of scales 24-25; transverse series of scales 9; scale rows around caudal peduncle 16. Contact organ on each scale of anteroventral portion of lateral surface of body in males. Minute papillate contact organs on medial surface of first pectoral-fin ray in males.

Cephalic neuromasts: supraorbital 2 + 6-8, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 15-16, preorbital 2, otic 1, post-otic 1-2, supratemporal 1, median opercular 1, ventral opercular 1, preopercular7-8, mandibular 5-6, lateral mandibular 1, paramandibular 1. One neuromast on center of each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, width about 40% of length; basihyal cartilage about 15% 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 25.


Males. Body and head light yellowish brown; flank with 11-12 red crimson bars alternating with narrow metallic blue bars; dorsal portion of blue bars wider and changing to yellow ochre; each side of head with four red crimson bars, one below eye and three on opercular region, alternating with light blue bars. Iris metallic blue, with vertical brownish red bar through center of eye. Basal and median portions of unpaired fins orange, sometimes with irregular yellow spots on dorsal and anal-fin bases; dark gray to black stripe along caudal fin margin and distal margin of dorsal and anal fins; narrow metallic blue line between orange and dark gray zones of unpaired fins. Pectoral fins grayish hyaline.

Females. Sides of head and body light yellowish brown, with 10-11 dark brown bars; one or two rounded black blotches on center of body. Iris yellow, anterior and posterior borders bright blue, with dark brown bar through center of eye. Unpaired fins pale yellow, with rounded black spots, larger and transversely elongated close to base of dorsal and anal fins. Pectoral fins grayish hyaline.


Floodplains of the rio Formoso, a tributary of rio Correntes, rio Paranaíba drainage, rio Paraná basin, Estado de Goiás, central Brazil (Fig. 1).


Temporary pools in Campo Úmido, in the Cerrado.