Simpsonichthys fasciatus

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 : 124-126

Simpsonichthys fasciatus Costa & Brasil, 2006

(Figs. 77)

Simpsonichthys fasciatus Costa & Brasil, 2006: 46 ( type locality: Unai , temporary pool about 2 km from the right bank of rio Preto, rio Paracatu drainage, rio Sao Francisco basin , about 16°41’30”S 46°30’00”W, altitude about 550 m, Estado de Minas Gerais, Brazil; holotype: UFRJ 6339 ).

Material examined

Brazil: Estado de Minas Gerais, rio Paracatu drainage, rio São Francisco basin: UFRJ 6339 , holotype, male, 19.7 mm SL; UFRJ 6340 , 7 paratypes; UFRJ 6341 , 4 paratypes (c&s); Brazil: Estado de Minas Gerais: Unai , temporary pool about 2 km from the right bank of rio Preto, rio Paracatu drainage, rio Sao Francisco basin ; G. C. Brasil, 15 Apr. 2005. UFRJ 6372 , 7 paratypes; MCP 39932 , 3 paratypes; UFRJ 6377 , 1 paratype; 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, about semicircular), and oblique bars on dorsal fin in males (vs. never a similar color pattern). Simpsonichthys fasciatus differs from S. alternatus and S. delucai in possessing dorsal-fin origin usually just anterior to anal-fin origin, sometimes slightly posterior, in a vertical through base of 2nd anal-fin ray (vs. dorsal-fin origin in 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 7. Largest specimen examined 20.0 mm SL. Dorsal profile 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, approximately straight on caudal peduncle. Body moderately deep, compressed, greatest body depth at level of pelvic-fin base. Eye positioned on dorsolateral portion of head side. Snout blunt. Urogenital papilla cylindrical and short in males, pocket-shaped in females.

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-fin s 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 in contact medially. Dorsal-fin origin often slightly anterior to anal-fin origin, or sometimes posterior to it, 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; pectoral-fin rays 12; pelvic-fin rays 6.

Frontal squamation E-patterned; E-scales overlapping medially; no row of scales anterior to G-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 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 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. Sides 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 to 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

Middle rio Preto drainage, itself a part of the rio Paracatu drainage, rio São Francisco basin, Unaí, Estado de Minas Gerais, Brazil (Fig. 4).

Habitat

Temporary pools in the Cerrado.