Austrolebias charrua, 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 : 182-184

Austrolebias charrua , sp. nov.

(Figs. 2-3)

Holotype. MZUSP 60070 , male, 47.2 mm SL: Brazil. Rio Grande do Sul. Temporary pool close to arroio Chuí , road to Barra do Chuí; W. J. E. M. Costa and A. C. Bacellar. 12 Sept. 1999 . Paratypes. Brazil. Rio Grande do Sul. MZUSP 60071 , 2 males, 38.1 -40.8 mm SL, and 3 females, 28.3-39.8 mm SL ; UFRJ 4950 , 19 males, 25.6- 45.0 mm SL, and 28 females, 25.5 -41.5 mm SL ; UFRJ 5061 , 3 males, 38.5 -42.9 mm SL, and 4 females, 30.2 -38.4 mm SL (e&s); all collected with holotype . — MCP 28027 , 8 males, 31.7-38.3 mm SL, and 8 females, 23.3 -33.8 mm SL; temporary swamp, km 5.5 of the road between Chuí and Barra do Chuí; W. J. E. M. Costa and A. C. Bacellar, 12 Sept. 1999 . - UFRJ 4990 , 22 males, 26.5 -40.1 mm SL. and 47 females, 23.3 -34.7 mm SL; same data as MCP 28027 . — UFRJ 5009 , 25 males, 24- 9- - 34.3 mm SL. and 17 females, 21.8-31.8 mm SL; same data as MCP 28027 . - UFRJ 5024 , 2 males, 35.7-37.3 mm SL, and 2 females, 36.8-37.2 mm SL; same data as MCP 28027 . — UFRJ 5006 , 3 males, 37.4-38.2 mm SL, and 7 females, 32.4-36.7 mm SL; temporary pool, 3 km N of Chuí, road BR-471; W. J. E. M. Costa and A. C. Bacellar, 12 Sept. 1999. - Uruguay. Rocha. MUCP 2542 , 10 males, 34.3 -44.0 mm SL, and 6 females, 28.8 -41.7 mm SL; temporary swamp close to arroyo San Miguel .. Chuy; M. Cheffe e G. Maurício, 30 Aug. 2000 .

Additional material (non type specimens). Brazil. Rio Grande do Sul. UFRJ 4948 , 43 ex.; ditch at road side, km 3 of the road between Chuí and Barra do Chuí; W. J. E. M. Costa and A. C. Bacellar. ll Sept. 1999 . - UFRJ 5008 . 9 ex; temporary pool, Chuí; W. J. E. M. Costa and A. C. Bacellar, ll Sept. 1999 . - UFRJ 5034 . 77 ex.: UFRJ 5035 , 5 ex. (c& s); temporary pool 2 km N of Curral Alto ; W. J. E. M. Costa and A. C. Bacellar. 14 Sept. 1999 . - UFRJ 4723 . 38 ex.: UFRJ 4724 , 8 ex. (c & s); temporary pool, road between Chui and Barra do Chuí; W. J. E. M. Costa, D. Belote ,, D. Almeida and F. Pupo, 19 Jul. 1998 .

Diagnosis. Similar to A. adloffi , A. minuano and A. nigrofasciatus by possessing two apomorphic color patterns, unique among species of Austrolebias , consisting of body side of male bright gray with dark gray to black stripes (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). lt differs from A. adloffi , A. minuano and A. nigrofasciatus by usually having more scales in the longitudinal series (28-30 vs. 26 -28) and more supraorbital neuromasts (19-24 vs. 16- 19). It is further distinguished from A. adloffi and A. nigrofasciatus by having more caudal-fin rays (23 -26 vs. 20-22) and 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 equal or wider than the light interspaces (vs. usually narrower), and from A. minuano by fewer second pharyngobranchial teeth (2-5 vs. 6-7).

Description. Morphometric data are given in Table 1. Male larger than female, reaching at least 47.2 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, compressed, body width approximately 2.7 times 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. Anteromedian 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 pectoral fm reaching vertical between base of sixth and ninth anal-fin ray in male, and between urogenital papilla and base of second anal-fm ray 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-fm origin, at vertical through urogenital papilla in female. Anal-fin origin of female at vertical through base of second dorsal-fin ray. Dorsal-fin rays: 21 -26 in male, 16 -22 in female. Anal-fin rays: 23 -29 in male, 21 - 25 in female. Caudal-fin rays: 23 -26. Pectoral-fin rays: ll-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: 28 -30. 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. Often small papillate contact organs on distal portion of first five anal-fin rays of male. No contact organs on dorsal fin and 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: 19-24.

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: 4 + 10-ll. Lateral process of sphenotic narrow, without anterior expansion. Dermosphenotic absent. Ventral process of posttemporal long. Total vertebrae: 28-31.

Coloration. Male. Side of body bright gray with iridescent blue spots, and with 8 - 15 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 blotch present in juvenile and adult female; dark stripes usually approximately equal in width or slightly wider that, light interspace, but sometimes stripes may be slightly narrower. Opercular and preopercular regions blue. 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 rounded to slightly elongated parallelly to rays; dorsal fin usually with pink iridescence, and caudal and anal fin with blue iridescence. 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; rarely one to three black spots on anterocentral portion of body side. Venter pale golden. Two black spots vertically arranged on posterior portion of caudal peduncle, often coalesced forming single S-shaped blotch, but sometimes very reduced or absent. Opercular and preopercular region pale blue. 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 charrua refers to the indigenous tribe formerly inhabiting southern Estado do Rio Grande do Sul, an area including the geographic range of the new species, a Portuguese name of uncertain origin. A noun in apposition.

Distribution. Known from some localities along the coastal plains of southern Rio Grande do Sul adjacent to lagoa Mirim, southern Brazil, between Curral Alto and Chuí (Fig. l).