Simpsonichthys mediopapillatus, Wilson J. E. M. Costa, 2006

Wilson J. E. M. Costa, 2006, Three new species of seasonal killifishes of the Simpsonichthys antenori species group (Teleostei: Cyprinodontiformes: Rivulidae) from the rio São Francisco basin, Brazil., Zootaxa 1306, pp. 25-39 : 30-34

Simpsonichthys mediopapillatus , new species

(Figs. 4-6)

Simpsonichthys ghisolfii non S. ghisolfii Costa , Cyrino & Nielsen; Costa, 2003: 41 (misidentification).

Holotype. UFRJ 5406 , males, 40.3 mm SL; Brazil: Estado da Bahia, temporary pool 8 km S of Pindai , rio Sao Domingos drainage, a tributary to the Rio Verde Pequeno, itself a tributary of rio Verde Grande, rio Sao Francisco basin , 14°33’36.7”S 42°42’9.8”W, altitude 628 m ; W. J. E. M. Costa, C. P. Bove & B. B. Costa, 23 Jan. 2002.

Paratypes. UFRJ 5408 , 2 males, 40.8-40.9 mm SL, 7 females, 32.0-38.2 mm SL; UFRJ 5407 , 1 male, 43.4 mm SL, 2 females, 32.5-36.7 mm SL (c&s); collected with holotype. UFRJ 6064 , 8 males, 26.9-30.1 mm SL, 4 females, 23.6-24.8 mm SL; UFRJ 6074 , 2 males, 28.0-30.5 mm SL, 2 females, 22.9-23.4 mm SL; MCP 40139 , 3 males, 27.7-28.9 mm SL; same locality and collectors, 15- 16 Jan. 2005.

Diagnosis. Distinguished from all other species of the S. antenori group in having a median neuromast on the posterior rostral series (Fig. 6) (vs. median rostral neuromast absent). Similar to S. ghisolfii , and distinguished from the other species of the S. antenori group , by possessing a long (vs. short) urogenital papilla in males (Fig. 6), zigzag shaped bars on caudal peduncle in males (vs. bars straight or slightly curved), and a distinctive narrow subdistal bright yellowish orange stripe on anal fin in males (vs. never a similar color pattern). Also distinguished from S. ghisolfii by the absence of contact organs on the flanks of males (vs. minute contact organs present on posterior border of anteroventral portion of flanks).

Description. Morphometric data appear in Table 1. Males larger than females, the largest male examined 43.4 mm SL, largest female examined 38.2 mm SL. Dorsal profile nearly straight on head, convex from nape to end of dorsal-fin base, nearly straight on caudal peduncle. Ventral profile convex from lower jaw to end of anal-fin base, approximately straight on caudal peduncle. Body deep, compressed, greatest body depth at level of pelvic-fin bases. Urogenital papilla cylindrical and long in males.

Tip of dorsal fin pointed in males, slightly pointed in females; tip of anal fin pointed in males, rounded in females. Tips of dorsal and anal fins with filamentous rays in males, tips reaching posterior portion of caudal fin. Caudal fin subtruncate in males, round in females. Pectoral fin elliptical. Posterior margin of pectoral fins reaching to vertical between base of 6th and 8th anal-fin rays in males, and between urogenital papilla and base of 1st analfin ray in females. Tip of each pelvic fin reaching to base of 3rd or 4th anal-fin ray in males and between urogenital papilla and base of 1st anal-fin ray in females. Pelvic-fin bases medially united. Dorsal-fin origin on vertical between base of 3rd and 4th anal-fin rays in males, and between base of 4th and 6th anal-fin rays in females; dorsal-fin origin between neural spines of vertebrae 7 and 8 in males, and neural spines of vertebrae 11 and 12 in females. Anal-fin origin between pleural ribs of vertebrae 7 and 8 in males, and pleural ribs of vertebrae 9 and 11 in females. Dorsal-fin rays 20-23 in males, 15-17 in females; anal-fin rays 21-23 in males, 19-21 in females; caudal-fin rays 22-24; pectoralfin rays 12; pelvic-fin rays 6.

Scales large, cycloid. Body and head entirely scaled, except on ventral surface of head. Trunk squamation slightly extending onto middle of anal-fin base. Scales extending onto anterior fifth of caudal fin. Frontal squamation E-patterned; E-scales overlapping medially; no scales anterior to H-scale; two or three supraorbital scales. Longitudinal series of scales 28-30; transverse series of scales 12-13; scale rows around caudal peduncle 16. No contact organs on scales. Small papillate contact organs on inner surface of three dorsalmost rays of pectoral fin in males.

Cephalic neuromasts: supraorbital 14-17, parietal 2-3, anterior rostral 1, posterior rostral with one lateral neuromast and middle neuromast, infraorbital 2 + 22-24, preorbital 3, otic 2, post-otic 3, supratemporal 1, median opercular 1, ventral opercular 1, preopercular 16-18, mandibular 13-15, lateral mandibular 4, paramandibular 1. One neuromast on each scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, longest width about 80 % of length; basihyal cartilage about 25 % of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 9. Gill-rakers on first branchial arch 4 + 11. Vomerine teeth absent. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae 29-30.

Coloration. Males: Sides of body light bluish gray, with white dots and 13-19 approximately straight and wide gray bars, more conspicuous and zigzag shaped on caudal peduncle. Dorsum pale brown. Venter light gray. Opercular region pale greenish blue. Iris light yellow, with dark purplish gray bar through center of eye. Dorsal fin greenish yellow, dark purplish pink on distal portion, with white dots; dorsal-fin filaments dark purple. Anal fin greenish yellow, with bluish white dots; subdistal zone bright yellowish orange, to light blue near fin tip; distal zone black; anal-fin filaments black. Caudal fin dark greenish yellow, with bluish white dots; broad bright blue zone on posterior margin of fin. Pectoral fins hyaline. Pelvic fins yellow, with black tips.

Females: Sides of body light gray, with 13-16 dark gray bars; venter pale golden; 1-3 rounded black blotches on anterocentral portion of flank; 1-7 irregularly arranged rounded black blotches on caudal peduncle. Dorsum pale brown. Venter light gray. Opercular region pale greenish golden. Iris light yellow, with gray bar through center of eye. Unpaired fins hyaline, with faint, longitudinally elongated gray spots; small, iridescent blue spot on posterior portion of anal fin close to caudal peduncle. Paired fins hyaline.

Distribution and habitat. Known from closely approximate, isolated temporary pools in the Caatinga, in the Rio Verde Grande drainage, Rio São Francisco basin, Estado da Bahia, Brazil (Fig. 3).

Etymology. From the Latin medium (middle) and papillatus (with papillae), referring to the unique possession of a neuromast on middle of the posterior rostral series.