Simpsonichthys ocellatus

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 : 56-59

Simpsonichthys ocellatus Costa, Nielsen & De Luca, 2001

(Figs. 34-35)

Simpsonichthys ocellatus Costa, Nielsen & De Luca, 2001: 25 ( type locality: temporary pool near rio Jequitinhonha, near Itaobim, road BR-367 , Estado de Minas Gerais, Brazil [approximately 16°40’S 41°40’W; altitude about 270 m]; holotype: MZUSP 61232 ).

Material examined

Brazil: Estado de Minas Gerais, rio Jequitinhonha basin: MZUSP 61232 , holotype, male, 33.9 mm SL; MZUSP 61233 , 20 paratypes; UFRJ 5096 , 9 paratypes; UFRJ 5097 , 60 paratypes; UFPJ 5098 , 8 paratypes (c&s); UFRJ 5102 , 208 paratypes; UMMZ uncatalogued, 24 paratypes; temporary pool 1 km W from Itaobim, road BR-367 ; W. J. E. M. Costa & C. P. Bove, 20 Apr. 2000. UFRJ 5099 , 4 paratypes; temporary pool 2.5 km W from Taquaral . UFRJ 5100 , 38 paratypes; temporary pool 9.5 km E from Sao Pedro do Jequitinhonha . UFRJ 5101 , 52 paratypes; temporary pool 20.5 km W from Almenara . UFRJ 5270 , 5; UFRJ 5148 , 1; temporary pool 2 km from rio Jequitinhonha, 18 km W from Salto da Divisa ; A. De Luca, D. Martins & V. Favalli, 24 Jun. 2000. UFRJ 5056 , 27; temporary pool near rio Jequitinhonha, 1 km from Itaobim ; D. Nielsen, Mar. 2000.

Diagnosis

Distinguished from all other congeners by having a large black blotch with wide bluish silver to light golden outline on anterocentral portion of flanks in females (vs. absence of metallic colors on flanks in females).

Description

Morphometric data appear in Table 4. Largest specimen examined 37.2 mm SL. Dorsal profile straight to slightly concave on head, convex from nape 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 side of head. Snout blunt. Urogenital papilla cylindrical and short in males, pocket-shaped in females.

Tip of dorsal fin slightly pointed in males, rounded in females; anal fin rounded in both sexes; filaments of dorsal and anal fins absent. Median dorsal-fin rays branched, anterior and posterior rays, including rays on fin tip, unbranched. Caudal fin subtruncate. Pectoral fins elliptical. Posterior margin of each pectoral fin reaching vertical through base of 4th anal-fin ray in males and through pelvic-fin base in females. Tip of each pelvic fin reaching base of 3rd anal-fin ray in males and urogenital papilla in females. Pelvic-fin bases in close proximity. Anal-fin origin usually posterior to dorsal-fin origin, on vertical through base of 2nd dorsal-fin ray, sometimes on vertical slightly anterior to dorsal-fin origin. Dorsal-fin origin between neural spines of vertebrae7 and 9 in males, between vertebrae 10 and 13 in females. Anal-fin origin between pleural ribs of vertebrae7 and 9 in males, between 10 and 11 in females. Dorsal-fin rays 21-26 in males, 16-20 in females; analfin rays 21-25 in males, 18-21 in females; caudal-fin rays 27-29; pectoral-fin rays 14-15; pelvic-fin rays 6.

Frontal squamation usually A-patterned, sometimes E-patterned; E-scales not medially overlapping; no scale anterior to H-scale. Supraorbital scales 2. Longitudinal series of scales 26-27; transverse series of scales 11; scale rows around caudal peduncle 12. Contact organ on each scale of ventral portion of flanks in males. Small papillate contact organs on inner surface of dorsalmost ray of each pectoral fin in males. Cephalic neuromasts: supraorbital 14, parietal 3-4, anterior rostral 1, posterior rostral 1, infraorbital 2-3 + 17-20, preorbital 3, otic 2, post-otic 1-2, supratemporal 1, median opercular 1, ventral opercular 2, preopercular and mandibular series sometimes united, preopercular 11-12, mandibular 8-12, lateral mandibular 3-7, paramandibular 1. One neuromast on center of each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, width about 70% of length; basihyal cartilage about 35% of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 3-4. Gill-rakers on first branchial arch 4 + 13. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 27-28.

Coloration

Males. Sides of body light brownish gray, with 10-13 pale brownish purple bars alternating with pale golden bars on anterior fourth and pale metallic blue on posterior three-fourths of flanks. Head light brownish gray, opercular region pale golden, with reddish brown bar on preopercle. Iris yellow, with dark brown bar through center of eye. Dorsal fin purplish gray, with small round pale blue spots. Anal fin purplish gray, with light blue bars. Caudal fin purplish gray with pale blue bars; often bars interrupted on dorsal portion forming rows of small spots. Pelvic fins light brown. Pectoral fins hyaline.

Females. Sides of body pale brown, with 10-11 faint light gray bars (more conspicuous in preserved specimens), alternating with short and narrow silver bars on median portion of flanks; usually one, rarely two elliptical black blotches with wide bluish silver to light golden contour, resulting in brilliant ocellated spot on anterocentral portion of flanks. Venter and head pale golden. Iris yellow, with faint brown bar through center of each eye. Fins hyaline.

Distribution

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

Habitat

Temporary pools in the Caatinga.