Simpsonichthys alternatus

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 : 122-124

Simpsonichthys alternatus (Costa & Brasil, 1994)

(Figs. 76)

Cynolebias alternatus Costa & Brasil, 1994b: 7 ( type locality: Joao Pinheiro [ Municipio ] close to rio Paracatu [near the city of Brasilandia ], rio Sao Francisco basin , Estado de Minas Gerais, Brazil [17°02’52.0”S 46°01’34.0”W; altitude 509 m]; holotype: MNRJ 12523 ).

Material examined

Brazil: Estado de Minas Gerais, rio Paracatu drainage, rio Sào Francisco basin: MNRJ 12523 , holotype, male, 22.7 mm SL; MNRJ 12524 , 2 paratypes; MZUSP 46082 , 3 paratypes; UFRJ 2129 , 1 paratype; UFRJ 3457 , 9; MNHN 1997.0048 , 6; UMMZ 231545 , 6; Brasilandia , Joao Pinheiro ; G. C. Brasil, 1 May 1994. UFRJ 2130 , 11 paratypes; UFRJ 2131 , 4 paratypes (c&s); same locality ; G. C. Brasil, 1 Jun. 1994. UFRJ 4636 , 25; same locality ; W. J. E. M. Costa, D. Belote, G. Neves & D. Almeida, 10 Apr. 1998. UFRJ 4750 , 4; same locality ; D. Nielsen & A. Carletto, 1 May 1996.

Diagnosis

Similar to S. delucai and S. fasciatus , and distinguished from the remaining species of the S. flammeus group by possessing a distal red bar on caudal fin in males (vs. broad metallic blue bar), a red distal stripe on anal fin in males (vs. no distinctive distal stripe), short to minute filamentous rays on tip of dorsal fin in males (vs. long filaments), and anal fin rounded in males (vs. pointed); differs from S. delucai by having dorsal fin pointed in males (vs. rounded to slightly pointed), dorsal fin with 6-8 bars through whole fin in males (vs. bars restricted to posterobasal portion of fin), and reddish gray bars on the side of body in males (vs. dark brown to black bars); differs from S. fasciatus in having dorsal-fin origin in vertical between base of 3rd and 5th anal-fin rays (vs. anterior to anal-fin base or in vertical between base of 1st and 2nd anal-fin rays) and red distal stripe on dorsal fin in males (vs. dark gray to black).

Description

Morphometric data appear in Table 7. Largest specimen examined 38.8 mm SL. Dorsal profile straight to slightly concave on head, convex from nape to end of dorsal-fin base, about 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 at level of pelvic-fin base. Eye positioned on dorsolateral portion of side of head. Snout blunt. Urogenital papilla cylindrical and short in males, pocket-shaped in females.

Tip of dorsal fin pointed in males, rounded in females; distal border of anal fin rounded in both sexes; median anal-fin rays long in females, anal fin spatula-shaped. Tip of dorsal fin with short filamentous rays in males, tips reaching vertical through caudal-fin base; no filamentous rays on anal fin. Caudal fin subtruncate in males, round in females. Pectoral fins elliptical. Posterior margin of pectoral fins reaching vertical through base of 6th anal-fin ray in males, and between base of 1st and 3rd anal-fin rays in females. Tip of pelvic fins reaching between base of 3rd and 4th anal-fin ray in males and reaching urogenital papilla in females. Pelvicfin bases medially in close proximity. Dorsal-fin origin in vertical between base of 3rd and 5th anal-fin rays in males, and between base of 2nd and 4th anal-fin rays in females. Dorsal-fin origin between neural spines of vertebrae8 and 9 in males, and neural spines of vertebrae 10 and 12 in females. Anal-fin origin between pleural ribs of vertebrae 7 and 8 in males, and pleural ribs of vertebrae 8 and 10 in females. Dorsal-fin rays 18-22 in males, 14-17 in females; anal-fin rays 21-24 in males, 18-20 in females; caudal-fin rays 23-24; pectoral-fin rays 12-13; pelvic-fin rays 6.

Frontal squamation E-patterned; E-scales overlapping medially; no scales anterior to G-scale; one supraorbital scale. Longitudinal series of scales 23-24; transverse series of scales 9-10; scale rows around caudal peduncle 12. Contact organ on each scale of ventral portion of lateral surface of body in males. Small papillate contact organs on inner surface of three dorsalmost rays of pectoral fins in males.

Cephalic neuromasts: supraorbital 13-18, parietal 4, anterior rostral 1, posterior rostral 1, infraorbital 2-3 + 19-21, preorbital 3, otic 2, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1, preopercular16-17, mandibular 11-13, lateral mandibular 5, paramandibular 1. One or two neuromasts on each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, width about 50% of length; basihyal cartilage about 35% of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 2-3. Gill-rakers on first branchial arch 3 + 10. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 25-27.

Coloration

Males. Sides of body bright brownish yellow, with 8-11 reddish gray bars slightly posteriorly inclined. Opercular region pale greenish golden. Iris light yellow, with dark brown bar. Dorsal fin light greenish yellow, with 6-8 reddish brown bars through the entire fin, connected to distal red stripe. Anal fin light greenish yellow, with 4-5 brown oblique bars and red distal stripe. Caudal fin light greenish yellow, with 3-5 reddish brown bars and red distal border. Pectoral fins hyaline. Pelvic fins reddish brown, with greenish yellow base.

Females. Side of body light yellowish gray, with one or two black spots on anterocentral portion of flank; sometimes faint gray bars on caudal peduncle. Opercular region pale greenish golden. Iris light yellow, with gray bar. Unpaired fins hyaline, with faint spots; small, iridescent blue spot on posterior portion of anal fin close to caudal peduncle. Paired fins hyaline.

Distribution

Rio Paracatu floodplains, rio São Francisco basin, Estado de Minas Gerais, Brazil (Fig. 4).

Habitat

Temporary pools in the Cerrado.