Austrolebias minuano, M Costa & Cheffe, 2001

M Costa, Wilson J. E. & Cheffe, Morevy M., 2001, THREE NEW ANNUAL FISHES OF THE GENUS Austrolebias FROM THE LAGUNA DOS PATOS SYSTEM, SOUTHERN BRAZIL, AND A REDESCRIPTION OF A. adloffi (AHL) (CYPRINODONTIFORMES: RIVULIDAE), Comun. Mus. Ciênc. Tecnol. PUCRS, Sér. Zool. 14 (2), pp. 179-200 : 185-187

Austrolebias minuano , sp. nov.

(Figs. 4-5)

Holotype. MCP 28028 , male, 46.1 mm SL; Brazil. Rio Grande do Sul. Temporary lagoon about 4.5 km N of Quinta , W. J. E. M. Costa and A. C. Bacellar, 10 Sept. 1999. Paratypes. Brazil. Rio Grande do Sul. MCP 28029 , 4 males, 33.3-41.8 mm SL, and 4 females, 32.0 -33.0 mm SL ; UFRJ 5036 , 24 males, 30.3 -46.5 mm SL, and 9 females, 33.0- 39.9 mm SL ; UFRJ 5037 , 2 males, 44.2-45.1 mm SL, and 2 females, 34.2-36.0 mm SL (c&s); all collected with holotype . - UFRJ 5032 , 6 males, 27.9 - 45.9 mm SL, and 2 females, 30.2 -33.3 mm SL; road to Cassino, 6 km before the city; W. J. E. M. Costa and A. C. Bacellar, 09 Sept. 1999 . MUCP 3622 , 8 males, 33,1 - 38,0 mm SL, and 13 females 31,0-41,1 mm SL; banhado do Maçarico, a 8 km da BR-471 , no distrito da Quinta, Rio Grande, RS; M. Cheffe, F. Silveira & D. Silveira, 15-VIII-2001 .

Diagnosis. Similar to A. adloffi , A. charrua and A. nigrofasciatus by possessing body side bright gray with dark gray to black stripes in male (vs. light gray or no stripes) and a vertically paired black blotch on the end of the caudal peduncle of juvenile and female (vs. small spots irregularly arranged, or a single round dorsally positioned spot, or no spots on caudal peduncle), two derived conditions not occurring in other congeners. It is distinguished from A. adloffi , A. charrua and A. nigrofasciatus by having more second pharyngobranchial teeth (6-7 vs. 2-5) and a rather deep body in adult male (to 48.6% SL vs. to 45.1 % SL), sometimes producing a unique discoid body morphology. This species also differs from A. charrua by having fewer supraorbital neuromasts (16-19 vs. 19-24) and fewer scales on the longitudinal series (26-28 vs. 28-30), from A. adloffi by female having dorsal-fin origin anterior to the anal-fin origin (vs. posterior to anal-fin origin) and a male color pattern with dark lateral stripes usually wider than the light interspaces (vs. usually narrower), and from A. adloffi and A. nigrofasciatus by having more caudal-fin rays (22-25 vs. 20 -22).

Description. Morphometric data are given in Table 2 . Male larger than female, reaching at least 46.5 mm SL. Dorsal profile convex between snout and end of dorsal-fin base, approximately straight on caudal peduncle. Protuberance on interorbital region of adult specimens of both sexes, more prominent in male. Ventral profile convex from lower jaw to end of anal-fin base, nearly straight on caudal peduncle. Body rather deep, often approximately reaching discoid morphology, compressed, body width approximately 2.4 in body depth in larger males. Longest body depth at vertical through anal-fin origin. Snout blunt. Jaws short.

Tip of dorsal and anal fins rounded. Border of membrane of anterior portion of dorsal fin of male not distinctively indented. Anteroinedian rays of anal fin of female lengthened, resulting in approximately triangular fin shape. Urogenital papilla of male not attached to anal fin. Caudal fin rounded. Pectoral fin elliptical. Posterior margin of the pectoral fin reaching vertical between base of fourth and fifth anal-fin ray in male, and between anus and urogenital papilla in female. Tip of pelvic fin reaching base of third anal-fin ray. Pelvic fins medially united along proximal half. Dorsal-fin origin at vertical through base of first or second anal-fin ray in male, and slightly anterior to anal-fin origin, at vertical through anus or urogenital papilla in female. Anal-fin origin of female at vertical through base of second or third dorsal-fin ray. Dorsal-fin rays: 21 -25 in male, 18 -22 in female. Anal-fin rays: 23 -27 in male, 21 - 24 in female. Caudal-fin rays: 22 -25. Pectoral-fin rays: 11- 12. Pelvic-fin rays: 5 -6.

Scales large, cycloid. Body and head entirely scaled. except on ventral surface of head. Frontal squamation F-patterned. No transverse rows of scales on anal-fin base. Pectoral-fin base naked. Longitudinal series of scales: 26 -28. Transverse series of scales: 12- 14. Scale rows around caudal peduncle: 16. Three to seven minute ctenii-like contact organs on each scale of lateral surface of body and opercular region of male. No contact organs on unpaired fins nor outer surface of pectoral and pelvic fins. Small papillate contact organs on inner surface of three dorsalmost rays of pectoral-fin of male. Supraorbital neuromasts: 16- 19.

Basihyal slightly widened, its longest width about 65-80% of its longitudinal length; basihyal cartilage long, about 55 % of total longitudinal length of basihyal, and with lateral projections. Six branchiostegal rays. Two to five teeth on second pharyngobranchial. Gill-rakers on first branchial arch: 3 + 10. Lateral process of sphenotic narrow, without anterior expansion. Dermosphenotic absent. Ventral process of posttemporal long. Total Venebrae: 27-30.

longitu-

length

Coloration. Male. Side of body bright gray with iridescent blue spots. sometimes golden on venter, with 8 - 14 dark vertical stripes; anterior stripes narrower and black, gradually changing to wider and dark purplish brown posteriorly; posteriormost stripe overlapped by black blotch, corresponding to the blotch present in juvenile and adult female; dark stripes usually approximately equal in width or slightly wider than light interspace, but sometimes stripes may be slightly narrower. Opercular and preopercular regions blue to bluish green. Black vertical suborbital stripe, and black oblique supraorbital stripe. Iris yellowish brown; dark gray vertical bar crossing eye. Unpaired fins dark gray with white small spots on their basal halves; basalmost spots of dorsal and anal fins slightly elongatcd parallelly to rays; dorsal fin with pink iridescence on distal half, and caudal and anal fins with blue iridescence on distal half. Pelvic fin bluish dark gray. Pectoral fin hyaline, with bluish black ventral edge.

Female. Side of body pale brownish gray, with light brown spots, usually vertically elongated, sometimes forming vertical stripes, but sometimes absent; never black spots on anterocentral portion of body sides. Venter pale golden. Two black spots vertically arranged on posterior portion of caudal peduncle, always coalesced forming single 8-shaped blotch. Opercular and preopercular region pale blue to pale greenish golden. Faint vertical, gray suborbital stripe. Iris light yellow; gray vertical bar crossing eye. Unpaired fins hyaline with small dark gray spots. Paired fins hyaline, sometimes gray stripe along ventral border of pectoral fin.

Etymology. The name minuano referring to the indigenous tribe inhabiting Estado do Rio Grande do Sul in the past, in an area occupied by the new species. A noun in apposition.

Distribution. Known only from some localities of the coastal plains close to the southernmost end of lagoa dos Patos, between Quinta and Rio Grande, southern Rio Grande do Sul, southern Brazil (Fig. l).