Simpsonichthys stellatus

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 : 61-63

Simpsonichthys stellatus (Costa & Brasil, 1994)

(Figs. 37-38)

Cynolebias stellatus Costa & Brasil, 1994b: 5 ( type locality: temporary pool 1 km N from the city of Sao Francisco , Estado de Minas Gerais, Brazil [approximately 15º50’S 44º50’W; altitude about 470 m]; holotype: MNRJ 12446 ).

Material examined

Brazil: Estado de Minas Gerais, rio São Francisco basin: MNRJ 12446 , holotype, male, 39.8 mm SL; UFRJ 2066 , 5 paratypes; UFRJ 2067 , 4 paratypes (c&s); MZUSP 45771 , 4 paratypes; MNRJ 12518 , 3 paratypes; temporary pool 1 km N of the city of Sao Francisco ; W. J. E. M. Costa, G. C. Brasil & C. Campinha, 7 Feb. 1994 . UFRJ 2121 , 6; UMMZ 230861 , 4; MNHN 1997 -0051, 4; MCZ 138940 , 4; temporary pool 7 km S from Sao Francisco ; G. C. Brasil, 13 Mar. 1994 . UFRJ 2121 , 101; UFRJ 5126 , 8 (c&s); temporary pool 1.4 km S from Sao Francisco ; W. J. E. M. Costa, F. Pupo & E. Araujo, 8 Feb. 1999 .

Diagnosis

Distinguished from all other species of the S. notatus group by possessing a combination of row of elongated light blue spots with black interspace on the basal portion of the dorsal fin in males (vs. never a similar color pattern) and a dark gray to black distal stripe on the anal fin in males (vs. no distinctive distal dark stripe).

Description

Morphometric data appear in Table 4. Largest specimen examined 37.9 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. Eye positioned on dorsal portion of head side. Snout blunt. Urogenital papilla cylindrical and short in males, pocket-shaped in females.

Tip of both dorsal and anal fins pointed in males, rounded in females. Short filamentous rays on tip of both dorsal and anal fins in males, tip of filaments reaching vertical through caudal-fin base. Anterior and posterior rays of dorsal-fin, including rays on tip of fin, unbranched; median rays branched. Caudal fin rounded. Pectoral fins elliptical. Posterior margin of pectoral fins reaching vertical through base of 4th anal-fin ray in males, and through urogenital papilla in females. Tip of each pelvic fin reaching between base of 4th and 6th anal-fin rays in males, and between urogenital papilla and base of 1st anal-fin ray in females. Pelvic-fin bases in close proximity. Anal-fin origin on vertical through base of 2nd or 3rd dorsal-fin ray in males, through dorsal-fin origin in females. Dorsal-fin origin between neural spines of vertebrae 7 and 9 in males, and neural spines of vertebrae 10 and 12 in females. Anal-fin origin between pleural ribs of vertebrae 7 and 9 in males, and pleural ribs of vertebrae 9 and 10 in females. Dorsal-fin rays 20-23 in males, 15-17 in females; anal-fin rays 19-21 in males, 17-19 in females; caudal-fin rays 25-28; pectoral-fin rays 14; pelvic-fin rays 6.

Frontal squamation A-patterned; E-scales slightly medially overlapped; no scale anterior to H-scale; supraorbital scales 2. Longitudinal series of scales 27; transverse series of scales 11; scale rows around caudal peduncle 16. Contact organ on each scale of anteroventral portion of flank in males. Small papillate contact organs on inner surface of dorsalmost ray of pectoral fin in males.

Cephalic neuromasts: supraorbital 11-15, parietal 3-4, anterior rostral 1-2, posterior rostral 1, infraorbital 2 + 19-21, preorbital 2-3, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 2, preopercular12-16, mandibular 10-11, lateral mandibular 5, paramandibular 1. One neuromast on center of each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, width about 60-65% 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 + 9. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 27- 28.

Coloration

Males. Sides of body dark yellow ochre, with 9-11 dark gray bars and light blue dots; venter yellowish white. Sides of head yellow ochre, with small blue spots on opercular region. Iris light yellow, with dark reddish brown bar through center of eye. Dorsal fin dark brownish red, with small round light blue spots; spots along dorsal fin base elongated, lateral interspace dark gray; row of blue spots along distal margin of dorsal fin. Anal fin light purplish gray, with dark gray oblique bars; distal edge dark gray to black. Caudal fin dark brownish red, with small round blue spots. Pelvic fins purplish gray, each with black tip. Pectoral fins hyaline.

Females. Sides of body light gray, with faint gray spots, sometimes coalesced to form bars; venter pale golden; one to three rounded black blotches on anterocentral portion of flanks. Opercular region pale greenish golden. Iris light yellow, with gray bar through center of eye. Unpaired fins hyaline, with faint gray spots on basal region; spots on anal fin elongated; small light blue spot on posterior margin of anal fin, just posterior to fin base. Paired fins hyaline.

Distribution

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

Habitat

Temporary pools in the Cerrado.