Austrolebias varzeae

Wilson J. E. M. Costa, 2006, The South American annual killifish genus Austrolebias (Teleostei: Cyprinodontiformes: Rivulidae): phylogenetic relationships, descriptive morphology and taxonomic revision., Zootaxa 1213, pp. 1-162 : 93-95

Austrolebias varzeae Costa, Reis & Behr

(Fig. 36)

Austrolebias varzeae Costa, Reis & Behr, 2004: 14 ( type locality: temporary lagoon close to rio da Varzea , Fazenda dos Branda, Carazinho, rio Uruguay basin , 28º18’ S 52º 48’W, Rio Grande do Sul, Brazil; holotype: MCP 29641 ).

Material examined

Brazil: Rio Grande do Sul: MCP 29641 , male holotype, 33.7 mm SL; MCP 23667 , 9 paratypes; UFRJ 5431 , 2 paratypes; UFRJ 5432 , 2 paratypes (c&s); temporary lagoon close to rio da Varzea , Fazenda dos Branda, Carazinho, rio Uruguay basin ; M. N. Xavier, 26 Aug. 1999.

Diagnosis

Distinguished from all other congeners by the combination of the following features: dark gray bars on flank in males, the three anteriormost bars distinctively darker and narrower, no contact organs on male anal fin, pelvic-fin bases separated by small interspace, anal fin short in females, urogenital papilla not attached to anal fin, dorsal-fin origin anterior to anal-fin origin, dorsal-fin rays 22-24 in males, 16-18 in females, anal-fin rays 23-26 in males, 18-19 in females, and longitudinal series scales 28-30.

Description

Morphometric data appear in Table 6. Males larger than females, largest male examined 33.7 mm SL, largest female 25.8 mm SL. Dorsal profile slightly concave on head, convex from nape to end of dorsal-fin base, approximately straight on caudal peduncle; no distinctive adipose ridge on frontal region. Ventral profile convex from lower jaw to end of anal-fin base, nearly straight on caudal peduncle. Greatest body depth at level of pelvic-fin base. Body deep and moderately compressed. Snout blunt and jaws short.

Tip of both dorsal and anal fins rounded. Anteromedian rays of anal fin of females not lengthened; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fins elliptical, short, posterior margin on vertical between pelvic-fin base and urogenital papilla. Tip of each pelvic fin reaching base of 2nd anal-fin ray. Pelvic-fin bases in close proximity. Urogenital papilla not attached to anal fin. Anal-fin origin on vertical through base of 2nd or 3rd dorsal-fin ray; dorsal-fin origin between neural spines of 8th and 9th vertebrae in males, between neural spines of 10th and 11th vertebrae in females. Anal-fin origin between pleural ribs of 9th and 10th vertebrae in males, between pleural ribs of 10th and 11th vertebrae in females. Dorsal-fin rays 22-24 in males, 16-18 in females; anal-fin rays 23-26 in males, 18-19 in females; caudal-fin rays 28-29; pectoral-fin rays 12; pelvicfin rays 5.

Scales large and cycloid. Trunk and head entirely scaled, except ventral surface of head. Sometimes few scales extending over anal-fin base; no scales on dorsal-fin base; three rows of scales on caudal-fin base. Frontal squamation F-patterned; E-scales not overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 28-30, scales regularly arranged; transverse series of scales 16-17; scale rows around caudal peduncle 20. One contact organ on each scale of ventral portion of flanks in males. Row of contact organs on three uppermost pectoral-fin rays in males. No contact organ on unpaired fins.

Cephalic neuromasts: supraorbital 17-18, parietal 1-2, anterior rostral 1, posterior rostral 1, infraorbital 3 + 20, preorbital 2, otic 3, post-otic 4-5, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 21-23, mandibular 15-16, lateral mandibular 4.

Basihyal subtriangular, width about 80 % of length; basihyal cartilage long, about 65 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Three to five teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3 + 9. Dermosphenotic ossification absent. Ventral process of posttemporal long. Total vertebrae 27-28.

Coloration

Males: sides of body bluish gray, with 9-11 dark gray bars, anterior three bars darker and narrower than interspace, remaining bars faint and wider than interspace. Urogenital papilla dark gray. Opercular and infraorbital bluish gray; nearly rectangular dark gray infraorbital bar, subtriangular dark gray supraorbital bar. Iris orangish brown, with dark brown bar through center of eye. Unpaired and pelvic fins dark bluish gray; white dots on entire dorsal fin, basal portion of anal fin, and dorsal portion of caudal fin; black distal line on anal fin. Pectoral fins hyaline.

Females: sides of body light yellowish brown, with round to slightly vertically elongated dark gray spots, darker on anterocentral portion of flank; no distinctive spot on caudal peduncle. Opercular region pale greenish golden. Iris orangish brown, with gray bar through center of eye. Infraorbital and supraorbital bars dark gray. Unpaired fins hyaline, with small gray spots on basal portion of anal fin; paired fins hyaline.

Distribution

Known only from rio da Várzea drainage, upper rio Uruguay basin, southern Brazil (Fig. 8).