Austrolebias viarius

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 : 117-120

Austrolebias viarius (Vaz-Ferreira, Sierra-de-Soriano & Scaglia-de-Paulete)

(Fig. 45)

Cynolebias viarius Vaz-Ferreira, Sierra-de-Soriano & Scaglia-de-Paulete, 1964: 1 ( type locality: temporary swamp at the edge of Ruta 15, between arroyo Valizas and balneario Aguas Dulces , 34º22’S 53°43’W, Departamento de Rocha, Uruguay; holotype: ZVC-P 798 ).

Material examined

Uruguay: Rocha: MNRJ 9748 , 2 paratypes (from ZVC-P 789); swamp at Ruta 15, close to balneario Aguas Dulces ; R. Vaz-Ferreira, B. Sierra-de-Soriano & J. Soriano, 29 Jul. 1963. MCP 15050 , 4 (1 c&s); swamp between km 267 and 275, road Valizas-Rocha ; R. Vaz-Ferreira & C. Rios, 7 Nov. 1970. MCP 15053 , 2; Ruta 10 ; C. Maspoli, Oct. 1990. CIMC 3503 , 17; confluence between road to Aguas Dulces and the road Castillos-Valizas ; M. Cheffe, 7 Aug. 2000. CIMC 3571 , 12; swamp at Ruta 10, between arroyo Valizas and balneario Aguas Dulces ; M. Cheffe, 5 Oct. 2000. UFRJ 6214 , 6; UFRJ 6215 , 6 (c&s); CTL 1387 , 107; Ruta 9, km 254.8 , 34°13.23’S 53°57.26’W; P. Laurino et al., 27 Aug. 2004. UFRJ 6216 , 4; CTL 1345 , 10; temporary swamp near arroyo Valizas, Ruta 10, km 267 , 34°21.55’S 53°50.64’W; P. Laurino et al., 27 Aug. 2004. CTL 1365 , 30; temporary swamp in Barra de Valizas , 34°19.34’S 53°49.36’W; P. Laurino et al., 27 Aug. 2004.

Diagnosis

Distinguished from all other species of the A. bellottii group by the following combination of features: no prominent contact organ on anal fin in males, urogenital papilla not attached to anal fin, dorsal-fin origin slightly posterior to anal-fin origin in males, flanks dark brown, with narrow light bars in males, anal-fin rays 23-26 in males, 19-22 in females, longitudinal series scales 29-30, frontal squamation F, G or H- patterned, and vertebrae 28-31.

Description

Morphometric data appear in Table 8. Males larger than females, largest male examined 61.0 mm SL, largest female 34.0 mm SL. Dorsal profile convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle; sometimes small adipose ridge on frontal region in males. 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 compressed. Snout blunt and jaws short.

Tip of both dorsal and anal fins rounded. Anteromedian rays of anal fin of females lengthened, anal fin shape approximately triangular; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fins elliptical, posterior margin on vertical between base of 2nd and 4th anal-fin rays in males, between anus and urogenital papilla in females. Tip of each pelvic fin reaching between base of 2nd and 3rd anal-fin rays in males, between urogenital base of 1st and 2nd anal-fin rays in females. Pelvic-fin bases medially united, medial pelvic-fin membranes about 10-60 % coalesced. Urogenital papilla not attached to anal fin. Dorsal-fin origin on vertical between base of 1st and 3rd anal-fin rays in males; dorsal-fin origin slightly anterior or posterior to anal-fin origin in females; dorsal-fin origin between neural spines of 8th and 10th vertebrae in males, between neural spines of 9th and 11th vertebrae in females. Anal-fin origin between pleural ribs of 7th and 9th vertebrae in males, between pleural ribs of 9th and 11th vertebrae in females. Dorsalfin rays 21-25 in males, 16-20 in females; anal-fin rays 23-26 in males, 19-22 in females; caudal-fin rays 22-25; pectoral-fin rays 11-13; pelvic-fin rays 5-6.

Scales large and cycloid. Trunk and head entirely scaled, except ventral surface of head. Usually no scales on dorsal and anal-fin bases, sometimes few scales slightly extending onto anal-fin base; three rows of scales on caudal-fin base. Frontal squamation often F-patterned, sometimes G or H-patterned; E-scales overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 29-30, scales regularly arranged; transverse series of scales 14-16; scale rows around caudal peduncle 20. Five to seven minute contact organs on each scale of ventral portion of flank in males. Row of minute contact organs on four uppermost pectoral-fin rays in males; sometimes minute contact organs on distal portion of anteriormost anal-fin rays in males. No contact organ on dorsal and caudal fins.

Cephalic neuromasts: supraorbital 16-18, parietal 4, anterior rostral 1, posterior rostral 1, infraorbital 2-3 + 25-26, preorbital 2, otic 3-4, post-otic 3-5, supratemporal 1, median opercular 1, ventral opercular 2, preopercular plus mandibular 39-40, lateral mandibular 4.

Basihyal nearly triangular, width about 65-85 % of length; basihyal cartilage moderate, about 50-60 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Five or six teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3-4 + 11-13. Dermosphenotic ossification absent. Ventral process of posttemporal long. Total vertebrae 28-31.

Coloration

Males: sides of body dark brown, with 8-11 narrow pale greenish yellow bars, anterior bars wider, posterior bars often represented by spots; sometimes faint similar bars through dark zones; often dark gray to black spot on anterocentral part of flanks. Urogenital papilla gray. Sides of head dark brown, opercular and infraorbital region bright greenish blue; approximately rectangular dark gray infraorbital bar; subtriangular dark gray supraorbital bar, not extending to neuromast parietal series. Iris dark brown, with black bar through center of eye. Dorsal and anal fins dark gray, with row of white dots on basal region; dorsal fin with pink iridescence; anal fin with blue iridescence. Caudal fin pale gray, with white dots over basal half of fin. Pelvic fins dark bluish gray. Pectoral fins grayish hyaline.

Females: sides of body light yellowish brown, with vertically elongated gray spots, sometimes forming short gray bars; venter pale golden; rarely a black spot on anterocentral portion of flanks; no black spot on posterior portion of caudal peduncle. Opercular region pale greenish yellow. Iris light yellow, with gray bar through center of eye. Infraorbital and supraorbital bars gray. Unpaired fins hyaline, with pale gray spots; paired fins hyaline.

Distribution

Isolated coastal drainages of southeastern Uruguay (Fig. 20).