Simpsonichthys gibberatus, Wilson J. E. M. Costa & Gilberto C. Brasil, 2006

Wilson J. E. M. Costa & Gilberto C. Brasil, 2006, Three new species of the seasonal killifish genus Simpsonichthys, subgenus Hypsolebias (Teleostei: Cyprinodontiformes: Rivulidae) from the rio Paracatu drainage, rio São Francisco basin, Brazil., Zootaxa 1244, pp. 41-55 : 50-53

Simpsonichthys gibberatus , new species

(Figs. 6-7)

Material examined

Holotype. UFRJ 6373, male, 27.9 mm SL; Brazil: Estado de Minas Gerais: Unaí, temporary pool about 2 km from the right bank of rio Preto, rio Paracatu drainage, rio São Francisco basin, about 16º41’30”S 46º30’00”W, altitude about 550 m; G. C. Brasil, 14 Feb. 2006.

Paratypes. UFRJ 6374, 5 males, 20.6-26.4 mm SL, 6 females, 17.9-21.9 mm SL ; UFRJ 6375, 4 males, 20.1-26.7 mm SL, 2 females, 21.3-21.5 mm SL (c&s) ; MCP 39437, 2 males, 18.9-19.2 mm SL, 2 females, 19.0-19.8 mm SL; all collected with holotype .

Diagnosis

Differs from all congeners by the unusual body morphology in females, in which there is a pronounced convexity of the dorsal profile in the region comprising the posterior portion of the head and the anterior portion of trunk, resulting in the greatest body depth at the level of the posterior margin of the opercle. S. gibberatus is also distinguished from all other species of the genus by the combination of the following features: frontal squamation A-patterned (vs. E-patterned), no distinctive rows of bright spots on distal margin of the dorsal fin in males (vs. row of bright blue spots present), gray bars on the flanks in females (vs. dark gray spots).

Description

Morphometric data appear in Table 1. Males larger than females, the largest male examined 27.9 mm SL; largest female examined 21.9 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 at level of pelvic-fin base in male, at level of posterior margin of opercle in females. Snout blunt. Urogenital papilla cylindrical and short in males; urogenital papilla protuberate in females, posterior border slightly overlapping anterior portion of anal fin, urogenital opening transverse.

Tip of both dorsal and anal fins pointed, with short filamentous rays in males and tip of longest filament reaching vertical through caudal-fin base. Dorsal and anal fins rounded in females, anal fin slightly lengthened. Most dorsal-fin rays unbranched. Caudal fin rounded. Pectoral fins elliptical. Posterior margin of pectoral fins reaching vertical between base of 6th and 8th anal-fins ray in males, and base of 3rd anal-fins ray in females. Tip of each pelvic fin reaching between base of 3rd and 4th anal-fin rays in males, reaching urogenital papilla in females. Pelvic-fin bases in contact medially. Dorsal-fin origin anterior to anal-fin origin, anal-fin origin on vertical between base of 4th and 5th dorsal-fin rays in males, between base of 1st and 3rd dorsal-fin rays in females. Dorsal-fin origin between neural spines of vertebrae 6 and 7 in males, between neural spines of vertebrae 11 and 12 in females. Anal-fin origin between pleural ribs of vertebrae 7 and 9 in males, between pleural ribs of vertebrae 10 and 12 in females. Dorsal-fin rays 21-26 in males, 15-17 in females; anal-fin rays 18-20 in males, 16-18 in females; caudal-fin rays 27-29 in both sexes; pectoral-fin rays 13-14 in both sexes; pelvic-fin rays 6 in both sexes.

Scales large, cycloid. Body and head entirely scaled, except on ventral surface of head. Trunk squamation extending slightly onto middle of anal-fin base. Scales extending onto anterior fifth of caudal fin. Frontal squamation A-patterned; E-scales overlapping medially; no row of scales anterior to H-scale; two small supraorbital scales. Longitudinal series of scales 25-27; transverse series of scales 8-9; scale rows around caudal peduncle 12. Prominent contact organ on each scale of anteroventral portion of flank in males. No contact organs on pectoral-fins.

Cephalic neuromasts: supraorbital 13-15, parietal 2-3, anterior rostral 1, posterior rostral 1, infraorbital 2-3 + 17-23, preorbital 3, otic 2, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1-2, preopercular plus mandibular 27-33, lateral mandibular 5-9, paramandibular 1. One neuromast on each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, the greatest width about 70 % of length; basihyal cartilage about 25 % of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 1-2. Gill-rakers on first branchial arch 2 + 9. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 27-28.

Coloration

Males: Sides of body light golden, with 9-11 light brown bars and horizontal series of small bright greenish blue spots; often dark gray to black spot on anterocentral portion of flanks. Dorsum light brown, venter yellowish white. Sides of head light golden to reddish brown on scales margins of dorsoposterior portion of head, with small greenish blue spots on center of scales; infraorbital region light golden. Iris light yellow, with reddish brown bar through center of each eye. Unpaired fins dark gray almost black, with small light blue spots; pale blue line on posterior margin of caudal fin. Pelvic fins dark gray. Pectoral fins hyaline.

Females: Sides of body light brownish gray, with 11-13 pale gray bars and 1 or 2 round black spot on anterocentral portion of flanks. Dorsum light brownish gray, venter light gray. Opercular region pale golden. Iris light yellow, with gray bar through center of eye. Fins hyaline.

Distribution

Known only from the type locality, middle rio Preto drainage, a part of rio Paracatu drainage, rio São Francisco basin, Unaí, Estado de Minas Gerais, Brazil (Fig. 3).

Habitat

Same as described for S. fasciatus .

Etymology

From the Latin gibberatus (with humped back), an allusion to the lateral profile of the anterodorsal portion of the body in females.