Pituna obliquoseriata, Costa, Wilson J. E. M., 2007

Costa, Wilson J. E. M., 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 : 16-18

Pituna obliquoseriata , new species

( Fig. 10 )

Pituna compacta non P. compacta (Myers) ; Costa, 1998b: 142 (misidentification).

Material examined. Holotype. UFRJ 6398 (male, 36.6 mm SL); Brazil: Estado de Mato Grosso, road MT- 326, 15– 16 km from the right bank of rio das Mortes, rio Araguaia basin, about 14°00’S, 51°40’W; W. J. E. M. Costa, G. C. Brasil, M. I. Landim & C. Moreira, 16 Feb. 1996.

Paratypes. Brazil: Estado de Mato Grosso: UFRJ 3543 (5 males, 27.4–30.8 mm SL, 7 females, 20.5–29.2 mm SL); UFRJ 3545 (1 male, 29.8 mm SL, 2 females, 21.8–27.6 mm SL [c&s]); MCP 40498 (1 male, 28.2 mm SL, 2 females, 23.3–24.2 mm SL); collected with holotype. UFRJ 247 (3 males, 29.8–37.5 mm SL, 18 females, 17.1–25.3 mm SL); UFRJ 294 (1 male, 36.7 mm SL); same locality; G. C. Brasil et al., Jan. 1988.

Diagnosis. Distinguished from all congeners in having more caudal-fin rays (28–31 vs. 24–28). It is also distinguished from all other species of the genus by the following combination of characters: 25–29 scales in longitudinal series (vs. 23–24), pectoral fins 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 flanks mainly obliquely arranged in females (vs. mainly longitudinally or irregularly arranged), 1 + 1+ 13–17 + 1 infraorbital neuromasts (vs. 1 + 1+ 17–21 + 1), and oblique rows of dark brown dots never forming bars on flank in females (vs. forming oblique bars).

Description. Morphometric data appear in Table 1 . Largest male examined 37.5 mm SL; largest female examined 29.2 mm SL. Dorsal profile weakly convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile gently convex from lower jaw to anal-fin origin, nearly straight along 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 each often with filamentous tip reaching to vertical through middle of caudal fin in males. Caudal fin rounded. Pectoral fins rounded, their posterior margin reaching vertical between pelvic-fin base and anus in males, through pelvic-fin base in females. Pelvic fins short, slightly pointed in males, elliptical in females; tip of each pelvic fin reaching between base of 1st and 3rd anal-fin rays in males, and base of 1st anal-fin ray in females. Pelvic-fin bases in close proximity medially. Dorsal-fin origin at vertical through base of 9th or 10th 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 9–10; anal-fin rays 13–15; caudal-fin rays 28–31; pectoral-fin rays 15–16; 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 45–50 % 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 7–9. Longitudinal series of scales 27–29; transverse series of scales 8; scale rows around caudal peduncle 16. Three to five contact organs on posterior margin of each scale of flank. No contact organs on fin rays.

Cephalic neuromasts: supraorbital 6–7 + 4–5, parietal 2, anterior rostral 1, posterior rostral 1, infraorbital 1 + 1 + 15–17 + 1, preorbital 4, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 10, mandibular 9, lateral mandibular 4, paramandibular 1. One neuromast per scale of lateral line. Two neuromasts on caudal-fin base.

Basihyal subtriangular, greatest width about 60 % 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 + 9. Vomerine teeth 2–4. Dermosphenotic present. Ventral process of posttemporal vestigial or absent. Total vertebrae 29.

Coloration. Males. Sides of body dark brown to purplish brown, with oblique rows of small greenish golden spots; dark metallic blue blotch on humeral region. Dorsum light brown. Venter light gray. Sides of head light greenish golden, scale borders brown; dark gray to black infraorbital bar, adjacent to narrow preorbital light gray bar. Jaws dark brown. Iris yellow, with dark brown bar through center of eye. Exposed part of branchiostegal membranes dark gray. Dorsal fin bright greenish blue, distal portion of median rays red, posterior portion of fin yellow with 3–4 short brown bars. Anal fin dark brown, orangish brown on distal portion; row of 6–7 yellow spots along fin base and posterior margin; sometimes transverse row of pale blue on subdistal region. Caudal fin dark purplish brown. Pectoral fins light blue, with 6–8 transverse rows of dark gray to black spots, sometimes coalesced to form bars. Pelvic fins orangish brown, with pale yellow spots on basal portion.

Females. Sides of head and trunk light gray, with dark brown dots arranged in oblique rows, often forming chevron-like pattern with tip posteriorly directed. 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 on basal portion. Paired fins hyaline.

Etymology. From the Latin obliquus (oblique) and seriatus (with series), referring to the oblique rows of dots on the flanks in females.

Distribution and habitat. Known only from the type locality, a temporary swamp near rio das Mortes, rio Araguaia basin, central Brazil ( Fig. 1 ), in a savannah area.

Figures

FIGURE 1. Geographic distribution of the genus Pituna. Triangle = P. schindleri; inverted triangle = P. xinguensis; star = P. brevirostrata; dots = P. poranga; square = P. c o m p a c t a; asterisk = P. obliquoseriata. One symbol may represent more than one collecting site.

FIGURE 10. Pituna obliquoseriata, UFRJ 6398, male holotype, 36.6 mm SL, above, UFRJ 3543, female paratype, 29.4 mm SL; Brazil: Mato Grosso: rio das Mortes floodplains. Photo by W. J. E. M. Costa.