Simpsonichthys trilineatus

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 : 77-79

Simpsonichthys trilineatus (Costa & Brasil, 1994)

(Fig. 51)

Cynolebias trilineatus Costa & Brasil, 1994b: 8 ( type locality: Joao Pinheiro close to the rio Paracatu [close to the city of Brasilandia ], rio Sao Francisco basin , Estado de Minas Gerais, Brazil [17º02’52.0”S 46º01’34.0”W; altitude 509 m]; holotype: MNRJ 12525 ).

Material examined

Brazil: Estado de Minas Gerais, rio Paracatu drainage, rio São Francisco basin: MNRJ 12525 , holotype, male, 24.3 mm SL; UFRJ 2132 , 1 paratype (c&s); Brasilândia; G. C. Brasil, 1 May 1994. MNRJ 12526 , 1 paratype; UFRJ 2133 , 2 paratypes; same locality as holotype ; G. C. Brasil, 1 Jun. 1994. UFRJ 4637 , 140; UFRJ 4670 , 10 (c&s); UFRJ 5272 , 2; UMMZ 234762 , 14; same locality as holotype ; W. J. E. M. Costa, D. Belote, G. Neves & D. Almeida, 10 Apr. 1998. UFRJ 4749 , 2; same locality as holotype ; D. Nielsen & A. Carletto, 1 May 1996.

Diagnosis

Similar to S. auratus and S. virgulatus , and distinguished from all other species of the S. notatus group by having anterior portion of flanks bright golden in males (vs. dark metallic yellow ochre) and by the presence of a dark brown humeral blotch in males (vs. absence in females). It differs from S. auratus and S. virgulatus by having five (vs. six) pelvic-fin rays, and three purplish brown stripes on posterior half of flanks in males (vs. never this color pattern).

Description

Morphometric data appear in Table 4. Largest specimen examined 49.2 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 deep, compressed, greatest body depth at level of pelvic-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 dorsal and anal fins pointed in males, rounded in females. Filamentous rays on tip of dorsal and anal fins in males, tip of filaments reaching vertical through posterior half of caudal fin. Dorsal-fin rays unbranched. Caudal fin rounded. Pectoral fins elliptical. Posterior margin of each pectoral fin reaching vertical between base of 4th and 7th anal-fin rays in males, and through urogenital papilla in females. Tip of each pelvic fin reaching base of 4th or 5th anal-fin ray in males, and between base of 1st or 2nd anal-fin ray in females. Pelvic-fin bases in close proximity. Anal-fin origin in vertical through base of the 2nd or 3rd dorsal-fin ray in males and 1st ray in females. Dorsal-fin origin between neural spines of vertebrae 7 and 9 in males and neural spines of vertebrae 10 and 13 in females. Anal-fin origin between pleural ribs of vertebrae 7 and 8 in males and pleural ribs of vertebrae 9 and 10 in females. Dorsal-fin rays 19-22 in males, 14-16 in females; anal-fin rays 18-22 in males, 16-18 in females; caudal-fin rays 26-27; pectoral-fin rays 13-14; pelvic-fin rays 5.

Frontal squamation A-patterned; E-scales slightly overlapping medially; no row of scales anterior to Fiscale; supraorbital scales 2. Longitudinal series of scales 27; transverse series of scales 8; scale rows around caudal peduncle 12. Contact organ on each scale of anteroventral portion of flank in males. Minute papillate contact organs on inner surface of dorsalmost ray of pectoral-fins in males.

Cephalic neuromasts: supraorbital 13-17, parietal 2, anterior rostral 1, posterior rostral 1, infraorbital 2 + 19- 21, preorbital 3, otic 2, post-otic 3, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 17- 18, mandibular 11-15, lateral mandibular 5, paramandibular 1. One neuromast on each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, width about 50% of length; basihyal cartilage about 25% of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 2. Gill-rakers on first branchial arch 3 + 10. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 27- 28.

Coloration

Males. Sides of body light yellowish gray, golden on anterior third; three purplish brown stripes, the median stripe continuous with vertical row of three round black blotches on anterior portion of flanks; six vertical rows of white dots on posterior two thirds of flanks; venter golden. Sides of head golden. Iris light yellow, with dark reddish brown bar through center of eye. Unpaired fins dark reddish brown, with white dots. Pelvic fins dark reddish brown. Pectoral fins hyaline, ventral edges pale orange.

Females. Sides of body light gray with dark gray spots, rarely vertically coalescent; venter pale golden; one or two rounded black blotches on anterocentral portion of flanks. Opercular region pale greenish golden. Iris light yellow, with gray bar through center of eye. Fins hyaline; small light blue spot on posterior margin of anal fin, just posterior to fin base.

Distribution

Middle rio Paracatu floodplains, middle rio São Francisco basin, Estado de Minas Gerais, Brazil (Fig. 1).

Habitat

Temporary pools in the Cerrado.