Austrolebias nigrofasciatus

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 : 129-133

Austrolebias nigrofasciatus Costa & Cheffe

(Fig. 49)

Austrolebias nigrofasciatus Costa & Cheffe, 2001: 187 ( type locality: temporary pool in Pontal da Barra, praia de Laranjal, Pelotas , Rio Grande do Sul, Brazil; holotype: MCP 21172 ).

Material examined

Brazil: Rio Grande do Sul: laguna dos Patos system: MCP 21172 , male holotype, 42.7 mm SL; UFRJ 4016 , 9 paratypes; temporary pool in Pontal da Barra, praia de Laranjal, canal de Sao Goncalo floodplains, Pelotas ; M. Cheffe, G. Mauricio & L. Matheus, 15 Oct. 1995. CIMC 3561 , 57 paratypes; same locality , M. Cheffe & G. Maurício, 1 Oct. 2000. MCP 21173 , 6 paratypes; UMMZ 234764 , 15 paratypes; UFRJ 4219 , 19 paratypes; same locality ; M. Cheffe & G. Mauricio, 16 Aug. 1993. UFRJ 4015 , 26 paratypes; M. Cheffe, G. Mauricio & L. Matheus, 7 Nov. 1993 [[ same locality ? ]]. UFRJ 4218 , 11 paratypes; same locality ; M. Cheffe, G. Mauricio & L. Matheus, 22 Aug. 1991. UFRJ 4259 , 13 paratypes; same locality ; M. Cheffe & G. Mauricio, 24 Sep. 1993. UFRJ 4014 , 7 paratypes (c&s); same locality ; G. Mauricio, 4 Dec. 1996. UFRJ 4220 , 37; same locality as holotype ; M. Cheffe, G. Mauricio & L. Matheus, 4 Jul. 1993. UFRJ 5007 , 19; UFRJ 5060 , 6 (c&s); temporary pool, road BR-116, 43 km NE of Arroio Grande ; W. J. E. M. Costa & A. C. Bacellar, 8 Sep. 1999. UFRJ 6167 , 2; UFRJ 6168 , 5 (c&s); CIMC 3401 , 20; temporary swamp in EMBRAPA near arroio Padre Doutor, canal de Sao Goncalo drainage, Capao do Leao ; M. M. Cheffe & G. N. Mauricio, 1 Sep. 1999.

Diagnosis

Distinguished from remaining species of the A. adloffi group by the combination of the following features: dorsal-fin origin usually anterior to anal-fin origin in both males and females, 21-26 anal-fin rays in males and 18-23 in females, 19-22 caudal-fin rays, maximum body depth 44.2 % SL in older males, 2-3 teeth on second pharyngobranchial in larger specimens, 27-29 vertebrae, a black broad bar on the posterior border of the dorsal and anal fins in male, a black bar on parietal series of neuromasts, dorsal and anal-fin bases with light blue bars, anterior flank bars usually narrower than interspace, posterior bars usually wider.

Description

Morphometric data appear in Table 9. Males larger than females, largest male examined 42.7 mm SL, largest female 36.8 mm SL. Dorsal profile convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle; adipose ridge on frontal region of head 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 nearly triangular; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fins elliptical, posterior margin on vertical between base of 5th and 6th anal-fin rays in males, and between anus and urogenital papilla in females. Tip of each pelvic fin reaching between base of 3rd and 5th anal-fin rays in males, between base of 1st and 3rd anal-fin rays in females. Medial pelvic-fin membranes 30-60 % coalesced. Urogenital papilla not attached to anal fin. Dorsal-fin origin usually anterior to anal-fin origin in males, anal-fin origin on vertical through base of 1st or 2nd anal-fin ray, sometimes dorsal-fin origin slightly posterior to anal-fin origin; dorsal-fin origin always anterior to anal-fin origin in females, anal-fin origin through base of 2nd or 3rd anal-fin ray; dorsal-fin origin between neural spines of 7th and 10th vertebrae in males, between neural spines of 8th and 11th vertebrae in females. Anal-fin origin between pleural ribs of 7th and 9th vertebrae in males, between pleural ribs of 8th and 11th vertebrae in females. Dorsal-fin rays 19-23 in males, 16-20 in females; anal-fin rays 21-26 in males, 18-23 in females; caudal-fin rays 19-22; pectoral-fin rays 10-12; pelvic-fin rays 5-6.

Scales large and cycloid. Trunk and head entirely scaled, except ventral surface of head. One row of scales on anal-fin base, no scales on dorsal-fin base, and three rows of scales on caudal-fin base. Frontal squamation usually F-patterned, rarely G or H- patterned; E-scales slightly overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 26-28, scales regularly arranged; transverse series of scales 11-12; scale rows around caudal peduncle 16. Three to seven minute contact organs on each scale of ventral portion of flank in male. Rows of minute contact organs on three uppermost pectoral-fin rays, 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 18-20, parietal 2-3, anterior rostral 1, posterior rostral 1, infraorbital 3 + 24-27, preorbital 2-3, otic 2-3, post-otic 3-6, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 21-25, mandibular 13-18, lateral mandibular 5.

Basihyal nearly triangular, width about 65-70 % of length; basihyal cartilage long, about 55-75 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Two to five teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3-4 + 9-10. Dermosphenotic ossification absent. Ventral process of posttemporal variable, usually short or absent, sometimes long. Total vertebrae 27-29.

Coloration

Males: sides of body metallic blue, with 6-12 dark brown to black bars, anterior bars darker and narrower, about half interspace width or slightly wider, posterior bars usually twice interspace width, sometimes equal in width; sometimes an 8-shaped black spot on posterior part of caudal peduncle. Urogenital papilla gray. Sides of head light blue on opercular and infraorbital regions; black infraorbital bar, wider close to eye, gradually narrowing ventrally, often tip posteriorly directed in larger specimens; elongated black supraorbital bar, with distinctive narrow extension over neuromast parietal series. Iris dark yellow, with dark brown bar through center of eye. Dorsal and anal fins dark bluish gray, with light blue bars on basal portion, anterior bars long, reaching distal margin of fin, posterior bars reaching median portion of fin and alternating with transverse series of elongated light blues spots on middle of fin; broad black bar, with anterior bright blue border on posterior portion of dorsal and anal fins; distal half of anal fin with blue iridescence. Caudal fin dark bluish gray, with elongated light blue spots on dorsobasal portion. Pelvic fins dark bluish gray. Pectoral fins hyaline, with bluish black ventral margin.

Females: sides of body light yellowish brown, with vertical rows of elongate gray spots, sometimes forming gray bars; venter pale golden; no black spot on anterocentral portion of flanks; usually two black spots vertically arranged on posterior portion of caudal peduncle, often coalesced to form an 8-shaped spot, which is occasionally absent. Opercular region pale greenish blue. Iris light yellow, with gray bar through center of eye. Infraorbital and supraorbital bars gray. Unpaired fins gray, with light gray bars on basal portion of dorsal and anal fins; paired fins hyaline, sometimes gray stripe along ventral border of pectoral fins.

Distribution

River drainages associated with the left margin of canal de São Gonçalo, laguna dos Patos system, Rio Grande do Sul, southern Brazil (Fig. 52).