Simpsonichthys fasciatus, 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 : 46-50

Simpsonichthys fasciatus , new species

(Figs. 4-5)

Material examined

Holotype. UFRJ 6339, male, 19.7 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, 15 April 2005.

Paratypes. UFRJ 6340, 4 males, 16.8-20.0 mm SL, 3 females, 15.7-16.3 mm SL ; UFRJ 6341, 2 males, 17.6-18.6 mm SL, 2 females, both 15.7 mm SL (c&s) ; all collected with holotype. UFRJ 6372, 5 males, 16.4-19.4 mm SL, 2 females, 15.4-16.7 mm SL ; MCP 39436, 3 males, 18.4-18.8 mm SL ; UFRJ 6377, 1 female, 15.9 mm SL; same locality; G. C. Brasil, 14 Feb. 2006 .

Diagnosis

Similar to S. alternatus and S. delucai , and distinguished from all other congeners in having the following combination of characters: anal fin rounded in males (vs. pointed), anal fin elongated, spatula-shaped in females (vs. short, nearly semicircular), and oblique bars on dorsal fin in males (vs. never with a similar color pattern). Simpsonichthys fasciatus differs from S. alternatus and S. delucai in usually having dorsal-fin origin just anterior (occasionally slightly posterior) to anal-fin origin, on a vertical through base of 2nd anal-fin ray (vs. dorsal-fin origin on a vertical between base of 3rd and 5th anal-fin rays), and a dark gray to black stripe on distal margin of dorsal fin in males (vs. dark red distal stripe).

Description

Morphometric data appear in Table 1. Males larger than females, the largest male examined 20.0 mm SL; largest female examined 16.7 mm SL. Dorsal profile slightly concave on head, convex from nape 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 and compressed, greatest body depth at level of pelvic-fin base. 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 dorsal fin pointed and tip of anal fin rounded in both sexes; anal fin long, spatula-shaped in females. Short filamentous rays on tip of dorsal fin in males, tip of longest filament reaching vertical through caudal-fin base. Most dorsal-fin rays unbranched. Caudal fin subtruncate in males, rounded in females. Pectoral fins elliptical. Posterior margin of pectoral fins reaching vertical between base of 4th and 6th anal-fins ray in males, through urogenital papilla in females. Tip of each pelvic fin reaching between base of 1st and 2nd anal-fin rays in males, reaching urogenital papilla in females. Pelvic-fin bases medially in contact. Dorsal-fin origin usually slightly anterior (sometimes posterior) to anal-fin origin, on vertical between base of 1st and 2nd anal-fin rays in males, and between base of 3rd and 4th anal-fin rays in females. Dorsal-fin origin between neural spines of vertebrae 7 and 8 in males, between neural spines of vertebrae 10 and 11 in females. Anal-fin origin between pleural ribs of vertebrae 7 and 9 in males, between pleural ribs of vertebrae 8 and 9 in females. Dorsal-fin rays 19-20 in males, 13-14 in females; anal-fin rays 20-21 in males, 17-19 in females; caudal-fin rays 22-24 in both sexes; pectoral-fin rays 12 in both sexes; pelvic-fin rays 6 in both sexes.

Scales large, cycloid. Body and head entirely scaled, except on ventral surface of head. Scales extending slightly onto middle of anal-fin base, and onto anterior fifth of caudal fin. Frontal squamation E-patterned; E-scales overlapping medially; no row of scales anterior to H-scale; two small supraorbital scales. Longitudinal series of scales 24-25; transverse series of scales 8-9; scale rows around caudal peduncle 12. Minute contact organ on each scale of anteroventral portion of flank in males. Small papillate contact organs on upper surface of dorsalmost ray of pectoral-fin in males.

Cephalic neuromasts: supraorbital 11-13, parietal 3, anterior rostral 1, posterior rostral 1, infraorbital 2-3 + 18, preorbital 3, otic 2, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1-2, preopercular 13-15, mandibular 10-12, lateral mandibular 4-5, paramandibular 1. One neuromast on each scale of lateral line. Two neuromasts on caudalfin base.

Basihyal subtriangular, the greatest width about 50 % of length; basihyal cartilage about 35 % of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 3. Gill-rakers on first branchial arch 3 + 10. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 25-26.

Coloration

Males: Side of body light pinkish gray, with 9-10 reddish brown bars. Dorsum light brown, venter yellowish white. Sides of head yellowish gray; narrow red pigmentation on scale margins of posterodorsal portion of head; opercular and infraorbital regions golden. Iris light yellow, with brown bar through center of eye. Dorsal fin light greenish blue, with 6-8 oblique dark reddish brown bars; dark gray to black stripe on distal margin of fin. Anal fin light greenish blue, becoming light yellowish gray on anterior portion, with 5 oblique dark reddish brown bars; distal portion of fin dark orangish red. Caudal fin light greenish blue, with 4 dark reddish brown bars. Pelvic fins reddish brown. Pectoral fins hyaline.

Females: Sides of body light brownish gray, usually with round black spot on anterocentral portion of flanks, sometimes two spots or spots absent; often faint gray bars on ventral portion of caudal peduncle. Dorsum light brownish gray, venter light gray. Opercular region pale greenish golden. Iris light yellow, with gray bar through center of eye. Fins hyaline.

Distribution

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

Habitat

Simpsonichthys fasciatus was collected in a small and shallow seasonal pool, area about 20 m2, and maximum depth about 0.4 m. At 10:00 AM on 26 May 2005, the water was clear, pH 5.7, temperature of the air 29.0°C, temperature of the water near the surface 23.1°C, and temperature of the water near the bottom 20.8°C. Simpsonichthys gibberatus was also collected in this same biotope. Other fish species found but not preserved were: Astyanax sp., Characidium sp. and Synbranchus sp.

Etymology

From the Latin fasciatus (with vertical bars), in reference to the male color pattern on the flanks and unpaired fins.