Plesiolebias altamira Costa & Nielsen, 2007

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 : 25-27

Plesiolebias altamira Costa & Nielsen , new species

(Figs. 16-17)

Material examined. Holotype. UFRJ 6369 (male, 17.1 mm SL), Brazil: Estado do Pará: temporary pool in island, rio Xingu, in front of Altamira, 3º13’34.6”S, 52°12’26.1”W, altitude 39m; J. L. Diniz, 5 May 2003.

Paratypes. Brasil: Estado do Pará: UFRJ 6370 (1 female, 18.1 mm SL) ; UFRJ 6371 (1 male, 17.5 mm SL, 2 females, 15.0-16.6 mm SL [c&s]); collected with holotype .

Diagnosis. Distinguished from all its congeners by the combination of the following characters: filamentous ray present on each pelvic fin in males (vs. filamentous ray absent); pelvic-fin rays 8 (vs. 7); eye yellow in males (vs. bright green); flank with oblique black bars in males (vs. black bars absent); red stripe on anterior portion of flank not anteriorly reaching orbit in males (vs. red stripe reaching orbit or absent); basal portion of dorsal fin red in males (vs. with transverse rows of dark red and white spots); a black spot on posterior portion of anal fin in males (vs. black spot absent); body depth 24.8-25.6 % SL in males, 23.0-26.0 % SL in females (vs. 28.6-32.6 % SL in males, 26.4-30.3 % SL in females); sparse bright dots on flank in males (vs. oblique rows of bright dots on flank); 3 white bars on basal portion of anal fin in males (vs. 4-5); a black bar on preopercle(vs. black bar absent); 8-9 oblique bars on flanks in females (vs. 5-7); 22-23 scales in longitudinal series (vs. 24-25).

Description. Morphometric data appear in Table 2. Largest male examined 17.5 mm SL, largest female 18.1 mm SL. Dorsal profile slightly convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile gently convex from lower jaw to end of anal-fin base, nearly straight on caudal peduncle. Body moderately slender, compressed. Greatest body depth at level of pelvic-fin base. Jaws short, snout blunt.

Tip of dorsal and anal fins rounded. Caudal fin rounded. Pectoral fins elliptical, posterior margin reaching vertical through base of 2nd anal-fin ray in males, through anus in females. Pelvic fins pointed in males, terminating in long filament, with tip reaching base of 9th anal-fin ray; tip of each pelvic fin reaching urogenital papilla in females. Pelvic-fin bases medially united. Dorsal-fin origin on vertical through base of 4th or 5th anal-fin ray, and between neural spines of 11th and 12th vertebrae. Anal-fin origin between pleural ribs of 9th and 11th vertebrae. Dorsal-fin rays 10-12; anal-fin rays 14-16; caudal-fin rays 23-25; pectoral-fin rays 12-13; pelvic-fin rays 8.

Scales large, cycloid. Body and head entirely scaled, except on anterior ventral surface of head. Body squamation extending onto anterior 25 % of caudal fin; no scales on dorsal and anal-fin bases. Frontal squamation G-patterned; E-scales overlapping medially; scales arranged in regular transverse pattern. Two supraorbital scales. Longitudinal series of scales 22-23; transverse series of scales 8; scale rows around caudal peduncle 12. Three to five minute contact organs on posterior margin of each scale of ventral portion of flank in males.

Cephalic neuromasts: supraorbital 5-6 + 5, parietal 2, anterior rostral 1, posterior rostral 1, infraorbital 1 + 24-26 + 1, preorbital 2, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 2, preopercular2 + 9, mandibular 7, lateral mandibular 2. One neuromast on center of each scale of lateral line of trunk. Two neuromasts on caudal-fin base.

Basihyal subtriangular, narrow, width about 30 % of length; basihyal cartilage about 20 % of basihyal length. Five branchiostegal rays. Four teeth on second pharyngobranchial. Gill-rakers of first branchial arch 1 + 8. One vomerine tooth. Ventral process of posttemporal absent. Total vertebrae 25-27.

Coloration. Males: Sides of body pale purplish gray, with 10-11 oblique dark gray to black bars, alternating with two rows of white dots on anterior half of flank and with single similar row on posterior portion of flanks; red spot extending between anterior part of dorsolateral region of trunk and posterior part of dorsolateral region of head. Dorsum light purplish brown. Venter pinkish white, with transverse dark gray marks. Sides of head pale pink, opercular region greenish golden; oblique black bar just posterior to orbit and another similar bar through preopercle; short oblique black infraorbital bar. Jaws dark gray. Iris yellow, with black bar through center of eye. Dorsal fin red, distal portion hyaline; small white spots on fin base. Anal fin black with three short white bars on its basal half, uniformly reddish black on distal half; faint light blue bar on posterior portion of fin. Caudal fin grayish hyaline, with transverse rows of small white spots, united to form narrow bars on ventral portion of fin. Pectoral fins hyaline. Pelvic fins black, with two white bars, anterior bar near anterior margin of each fin and posterior bar on posterior margin.

Females: Sides of body light brownish gray, with 8-9 wide oblique gray bars. Dorsum light brown. Venter white. Sides of head light brown, pale greenish yellow on opercle. Jaws gray. Iris pale yellow, with gray bar through center of eye. Fins hyaline.

Etymology. The name altamira is an allusion to the occurrence of the new species near the city of Altamira, Brazilian Amazon.

Distribution and habitat. Known only from seasonal pools near the city of Altamira, rio Xingu drainage, rio Amazonas basin, Estado do Pará, Brazil (Fig. 13).