Simpsonichthys similis

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 : 70-72

Simpsonichthys similis Costa & Hellner, 1999

(Figs. 45-46)

Simpsonichthys similis Costa & Hellner, 1999: 90 ( type locality: temporary pool close to Urucuia, road to Sao Romao , rio Urucuia basin , Estado de Minas Gerais, Brazil [approximately 16°05’S 45°45’W; altitude about 500 m]; holotype: MZUSP 51834 ).

Material examined

Brazil: Estado de Minas Gerais, rio Urucuia drainage, rio São Francisco basin: MZUSP 51834 , holotype, male, 28.4 mm SL; MZUSP 51835 , 1 paratype; UFRJ 4146 , 1 paratype female; UFRJ 4147 , 5 paratypes (c&s); temporary pool close to Urucuia ; S. Hellner & K. Schoelzel, Apr. 1995. UFRJ 4148 , 1 paratype; born in aquarium, descendant of fishes collected with the holotype .

Diagnosis

Distinguished from remaining species of S. notatus group in possessing the following combination of characters: often one or two black blotches on anterocentral portion of flanks in males (vs. blotch always absent), white dots on all unpaired fins in males (vs. never all fins with light dots), row of small blue spots on distal margin of dorsal fin in males (vs. distal blue stripe or no distinctive distal blue mark), anterior portion of flanks dark metallic yellow ochre in males (vs. bright golden), and absence of humeral dark brown blotch in males (vs. presence).

Description

Morphometric data appear in Table 4. Largest specimen examined 43.3 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 dorsal and anal fins slightly pointed in males, rounded in females. Short filamentous rays on tip of dorsal and anal fins in males, tip of filaments reaching vertical through caudal-fin base. Dorsal-fin rays unbranched. Caudal fin rounded. Pectoral fin elliptical. Posterior margin of each pectoral fin reaching vertical through base of 2nd anal-fin ray in males, and through pelvic-fin base in females. Tip of each pelvic fin reaching base of 2nd anal-fin ray in males, and urogenital papilla in females. Pelvic-fin bases in close proximity. Anal-fin origin on vertical through base of 3rd dorsal-fin ray in males, through base of 1st dorsal-fin ray in females; dorsal-fin origin between neural spines of vertebrae 7 and 9 in males, and neural spines of vertebrae 11 and 12 in females. Anal-fin origin between pleural ribs of vertebrae 7 and 9 in males, and pleural ribs of vertebrae 10 and 11 in females. Dorsal-fin rays 22-23 in males, 16-18 in females; anal-fin rays 20-21 in males, 17 in females; caudal-fin rays 26-29; pectoral-fin rays 14; pelvic-fin rays 6.

Frontal squamation A-patterned; E-scales medially slightly overlapping; no scale anterior to H-scale; supraorbital scales 2. Longitudinal series of scales 27; transverse series of scales 10; 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 pectoral fin in males.

Cephalic neuromasts: supraorbital 11-14, parietal 3-4, anterior rostral 1, posterior rostral 1, infraorbital 2 + 19, preorbital 3, otic 2, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1-2, preopercular 15, 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 75-80% of length; basihyal cartilage about 20% of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 2. Gill-rakers on first branchial arch 3 + 10. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 27-28.

Coloration

Males. Sides of body metallic yellow ochre, with 11-12 dark purplish brown bars and light blue dots; sometimes one or two black blotches on anterocentral portion of flanks, often blotches absent; venter pale orangish golden. Sides of head yellow ochre, with small green spots on opercular region. Iris light yellow, with dark reddish brown bar through center of eye. Unpaired fins dark purplish brown to dark gray, with small white spots, usually small, rounded, sometimes elongated and parallel to fin rays; subdistal row of blue dots on distal margin of caudal fin; sometimes spots of caudal and anal fins distally elongated. Pelvic fins dark purplish brown. Pectoral fins hyaline.

Females. Sides of body light gray, with faint 11-12 gray 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; small light blue spot on posterior margin of anal fin, just posterior to fin base. Paired fins hyaline.

Distribution

Rio Urucuia drainage, middle rio São Francisco basin, Estado de Minas Gerais, Brazil (Fig. 1).

Habitat

Temporary pools in the Cerrado.