Pituna compacta (Myers)

Wilson J. E. M. Costa, 2007, Taxonomy of the plesiolebiasine killifish genera Pituna, Plesiolebias and Maratecoara (Teleostei: Cyprinodontiformes: Rivulidae), with descriptions of nine new species., Zootaxa 1410, pp. 1-41 : 11-13

Pituna compacta (Myers)

(Figs. 6-7)

Rivulus compactus Myers, 1927 : 120 (type locality: shallow lake, Donna Francisquinha, Porto Nacional, rio Tocantins, Goays [now Estado do Tocantins], Brazil [about 11°20’S 48°20’W]; lectotype: CAS 40707, designated by Huber, 1992: 157) .

Material examined. Brazil: Estado do Tocantins: rio Tocantins basin: CAS 40707 (lectotype, female, 25.5 mm SL); Dona Francisquinha, Porto Nacional; C. Ternetz, 16 Feb. 1924 . UFRJ 2101 (11), temporary lagoon close to rio Dona Francisquinha, Porto Nacional; W. J. E. M. Costa, G. C. Brasil & C. Campinha, 16 Feb. 1994 . UFRJ 2099 (29) ; UFRJ 2115 (2 [c&s]), temporary lagoon near rio Tocantins, Brejinho de Nazaré; W. J. E. M. Costa, G. C. Brasil & C. Campinha, 16- 16 Feb. 1994 . UFRJ 6391 (2) ; UFRJ 6392 (2 [c&s]), temporary swamp 2 km from rio Canabrava, rio Santa Tereza drainage, rio Tocantins basin, road TO-373 12 km from the road BR-153, 12°29’46.3”S 49°0’50.7”W, altitude 292 m; W. J. E. M. Costa, C. P. Bove, J. Paz & A. Oliveira, 16 Apr. 2006 . UFRJ 3797, (2), 10 km of Salvação, Alvorada; D. T. B. Nielsen, A. Carletto & A. de Luca, 5 Apr. 1996 . UFRJ 5118 (1), pool near Peixe; G. C. Brasil, 20 Apr. 2000 . UFRJ 4090 (4), pool near left bank of rio Tocantins, Itaguatins; G. C. Brasil, 20 Apr. 1997 .

Diagnosis. Distinguished from all congeners by the following combination of characters: 25-29 scales in longitudinal series (vs. 23-24), pectoral fin with vertical rows of small dark gray spots or dark gray bars in males (vs. pectoral fin without dark marks), frontal squamation F-patterned (vs. D-patterned), anterior section of supraorbital series of neuromasts continuous (vs. interrupted), dark marks on flank mainly longitudinally arranged in females (vs. mainly obliquely or irregularly arranged), body depth 24.6-27.2 % SL in males and 24.1-26.3 % SL in females (vs. 21.3-24.6 % SL in males and 18.1-23.8 % SL in females), caudal peduncle depth 17.6-19.5 % SL in males and 15.6-17.9 % SL in females (vs. 15.5-17.1 % SL in males and 14.7-15.7 % SL in females), head depth 74.9-80.7 % SL in males and 71.8-77.1 % SL in females (vs. 69.4-75.4 % SL in males and 65.2-68.1 % SL in females), and 7-8 bars or transverse rows of spots on pectoral fins in males (vs. 4-5).

Description. Morphometric data appear in Table 1. Largest male examined 39.7 mm SL; largest female examined 35.8 mm SL. Dorsal profile slightly convex from snout to end of dorsal-fin base, about straight on caudal peduncle. Ventral profile gently convex from lower jaw to anal-fin origin, approximately straight to end of caudal peduncle. Body slender, subcylindrical, slightly deeper than wide, greatest body depth at level of pelvic-fin base. Jaws short, snout blunt.

Dorsal and anal fins pointed in both sexes, longer and often with filamentous tip reaching to vertical through base of caudal fin in males. Caudal fin rounded. Pectoral fins rounded, posterior margin of each fin reaching vertical through anus in males, between pelvic-fin base and anus in females. Pelvic fins short, slightly pointed in males, elliptical in females; tip of each pelvic fin reaching between base of 2nd and 4th analfin rays in males, and base of 1st anal-fin ray in females. Pelvic-fin bases medially in close proximity. Dorsalfin origin at vertical through base of 10th or 11th anal-fin rays, between neural spines of vertebrae 18 and 20. Anal-fin origin between pleural ribs of vertebrae 12 and 14. Dorsal-fin rays 8-10; anal-fin rays 14-16; caudalfin rays 26-28; pectoral-fin rays 14-15; pelvic-fin rays 7.

Scales large, cycloid. Body and head entirely scaled, except on anteroventral surface of head. No scales on dorsal and anal-fin bases. Scales extending onto anterior 45 % of caudal fin. Frontal squamation F-patterned, frontal scales circularly arranged around A-scale without free margins; E-scales not overlapping; row of scales anterior to H-scale; supraorbital scales 5-7. Longitudinal series of scales 26-27; transverse series of scales 7-8; scale rows around caudal peduncle 16. Three to five contact organs on posterior margin of each scale of flanks and opercular region. No contact organs on fin rays.

Cephalic neuromasts: supraorbital 6 + 5-6, parietal 1-2, anterior rostral 1, posterior rostral 1, infraorbital 1 + 1 + 16 + 1, preorbital 5, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1-2, preopercular 11-12, mandibular 8-9, lateral mandibular 3, paramandibular 1. One neuromast per scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, greatest width about 55 % of length; basihyal cartilage about 35 % of total length of basihyal. Six branchiostegal rays. Second pharyngobranchial teeth 3. Gill-rakers on first branchial arch 1 + 8-9. Vomerine teeth 1-3. Dermosphenotic present. Ventral process of posttemporal vestigial or absent. Total vertebrae 28-29.

Coloration. Males. Sides of body reddish brown, with oblique rows of small golden spots; vertically elongated, dark metallic blue blotch on humeral region. Dorsum light brown. Venter light gray. Sides of head greenish golden, scale borders reddish brown; dark gray to black infraorbital bar, adjacent to narrow preorbital light gray bar. Jaws reddish brown. Iris yellow with dark brown bar through center of eye. Exposed parts of branchiostegal membranes dark gray. Dorsal fin bright blue, distal portion of median rays red; 5-6 brown bars on posterior edge of fin. Anal fin orangish brown, with transverse rows of faint yellow spots, to dark brown with 7 short yellow bars on basal and posterior portions; distal margin dark gray to black. Caudal fin purplish brown, with transverse rows of small pale blue spots. Pectoral fins light blue, with 7-8 transverse rows of dark gray to black spots, often coalesced to form bars. Pelvic fins orangish brown, with pale yellow spots on basal portion.

Females. Sides of head and trunk light gray, with small brown spots, irregular and simultaneously arranged in horizontal and oblique rows. Dorsum light brown. Venter light gray. Opercular region pale greenish golden. Dark gray infraorbital bar, adjacent to narrow preorbital light gray bar. Jaws brown. Iris yellow, with dark brown bar through center of eye. Unpaired fins hyaline, with faint small brown spots. Paired fins hyaline.

Distribution and habitat. Temporary pools of the middle rio Tocantins basin (Fig. 1), in typical savannah environments.