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: 21-22
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Simpsonichthys perpendicularis ZBK Costa, Nielsen & De Luca, 2001: 26 ( type locality: temporary pool near ribeirao do Salto, road between Itarantim and Jordania , about 6 km from Jordania , rio Jequitinhonha basin , Estado da Bahia, Brazil [approximately 15°55’S 40°10’W; altitude about 190 m]; holotype: MZUSP 62570GoogleMaps ).
Brazil: Estado da Bahia, rio Jequitinhonha basin: MZUSP 62570, holotype, male, 43.3 mm SL; MZUSP 62571, 5 paratypes; UFRJ 5144, 10 paratypes; UFRJ 5145, 5 paratypes (c&s); temporary pool in ribeirao do Salto floodplains, road between Itarantim and Jordania , about 6 km from Jordania ; A. C. De Luca, D. S. U. Martins & V. S. Favalli, 23 Jun. 2000.
Distinguished from all other congeners by the unique color pattern in males, consisting of bars on anterior half and three stripes on the posterior half of flank. It is also distinguished from the other species of Ophthalmolebias in possessing more gill-rakers on the first branchial arch (4 + 14, vs. 2-4 + 11) and more dorsal-fin rays in females (16-18, vs. 13-16).
Morphometric data appear in Table 1. Largest male examined 43.3 mm SL. Dorsal profile 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 lateral portion of head. Snout blunt to slightly pointed. Urogenital papilla cylindrical and short in males, pocket-shaped in females.
Tip of dorsal fin weakly pointed in males, rounded in females; tip of anal fin rounded in both sexes. Tip of both dorsal and anal fins with filamentous rays in males, the longest dorsal-fin filaments reaching posteriorly to vertical through middle of caudal fin; tip of anal-fin filaments reaching vertical through base of caudal fin. Dorsal-fin rays unbranched. Caudal fin rounded. Pectoral fins elliptical. Posterior margin of each pectoral fin reaching vertical through base of 4th anal-fin ray in males and between pelvic-fin base and anus in females. Tip of each pelvic fin reaching base of 3rd or 4th anal-fin ray in males and between urogenital papilla and anal-fin origin in females. Pelvic-fin bases medially in close proximity. Dorsal-fin origin on vertical through base of 5th or 6th anal-fin ray, between neural spines of vertebrae 11 and 12 in both sexes. Anal-fin origin between pleural ribs of vertebrae 8 and 9 in males and between pleural ribs of vertebrae 9 and 10 in females. Dorsal-fin rays 17-20 in males, 16-18 in females; anal-fin rays 23-25 in males, 21-23 in females; caudal-fin rays 25-27; pectoral-fin rays 13; pelvic-fin rays 6.
Frontal squamation E-patterned; E-scales overlapping medially; no scales anterior to H-scale; one supraorbital scale. Longitudinal series of scales 26-28; transverse series of scales 9-10; scale rows around caudal peduncle 14. Contact organ on each scale of anteroventral portion of lateral surface of body in males. Small papillate contact organs on inner surface of dorsalmost pectoral-fin ray in males.
Cephalic neuromasts: supraorbital 8 + 5-6, parietal 2-3, anterior rostral 1, sometimes absent, posterior rostral 1, infraorbital 2 + 19-20, preorbital 2, otic 2, post-otic 3, supratemporal 1, median opercular 1, ventral opercular2, preopercular 14-15, mandibular 10, lateral mandibular 3, paramandibular 1. One or two neuromasts on center of each scale of lateral line. Two neuromasts on caudal-fin base.
Basihyal subtriangular, width about 55% of length; basihyal cartilage about 30% of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 2-3. Gill-rakers on first branchial arch 4 + 14. Vomerine teeth absent. Dermosphenotic present. Ventral process of posttemporal long. Total vertebrae 27-28.
Males. Sides of body light purplish brown to pale golden anteriorly; 7-10 pale brown bars between vertical through pectoral-fin base and middle of dorsal-fin base and 3 purplish brown stripes on posterior half of body; posterior two bars overlapping anterior portion of stripes. Opercular region golden. Iris yellow, with purplish brown bar through center of eye. Pelvic and unpaired fins pale yellow, with dark gray spots. Pectoral fins hyaline, with dark gray ventral border.
Females. Sides of body pale brown, with 11-12 dark gray bars between head and caudal-fin base; usually one or two black blotches, rarely three, on anterocentral portion, alternated with light blue vertically elongated spots. Opercular region pale golden. Iris yellow, with grayish brown bar through center of eye. Dorsal fin hyaline, with dark gray round spots. Caudal fin hyaline, pale pink ventrally. Anal fin pink, with faint metallic blue spots. Paired fins hyaline.
Known only from the type locality, ribeirão do Salto floodplains, middle rio Jequitinhonha basin, Estado da Bahia, northeastern Brazil (Fig. 4).
The type locality is a temporary pool within an area where the original forest was destroyed, in a cattle area. Simpsonichthys perpendicularis ZBK was not found elsewhere and is considered a vulnerable species (Costa, 2002).
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