Austrolebias minuano

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 : 124-126

Austrolebias minuano Costa & Cheffe

(Fig. 47)

Austrolebias minuano Costa & Cheffe, 2001: 185 ( type locality: temporary lagoon about 4.5 km N of Quinta , Rio Grande do Sul, Brazil; holotype: MCP 28028 .

Material examined

Brazil: Rio Grande do Sul: laguna dos Patos system: MCP 28028 , holotype, male, 46.1 mm SL; MCP 28029 , 8 paratypes; UFRJ 5036 , 33 paratypes; UFRJ 5037 , 4 paratypes (c&s); temporary lagoon about 4.5 km N of Quinta ; W. J. E. M. Costa & A. C. Bacellar, 10 Sep. 1999. CIMC 4622 , 21 paratypes; banhado do Macarico , 8 km of the road BR-471, distrito da Quinta, Rio Grande ; M. Cheffe, F. Silveira & D. Silveira, 15 Aug. 2001. UFRJ 5032 , 6 paratypes; UFRJ 6176 , 2 paratypes (c&s); road to Cassino, 6 km before the city ; W. J. E. M. Costa & A. C. Bacellar, 9 Sep. 1999. CIMC 3435 , 6; UFRJ 6177 , 2; UFRJ 6178 , 3 (c&s); swamp at the road BR-101, Tavares ; G. Mauricio, 1 Oct. 1999. CIMC 3587 , 21; UFRJ 6179 , 6 (c&s); swamp 3 km S of Bojuru, Sao Jose do Norte ; G. Mauricio & J. Mahler, 24 Oct. 2000. CIMC 3588 , 19; temporary swamp in Capao do Meio, Sao Jose do Norte ; G. Mauricio & J. Mahler, 25 Oct. 2000. CIMC 3590 , 17; temporary swamp in Sao Caetano, 20 km NE Sao Jose do Norte ; G. Mauricio & J. Mahler, 25 Oct. 2000. CIMC 3522 , 19; UFRJ 6180 , 4 (c&s); swamp at the road BR-101, 2 km from Tavares ; G. Mauricio & N. Jaegar, 24 Aug. 2000.

Diagnosis

Distinguished from remaining species of the A. adloffi group by the combination of the following features: dorsal-fin origin posterior to anal-fin origin in males and slightly anterior in females, 23-28 anal-fin rays in males and 21-26 in females, 21-25 caudal-fin rays, maximum body depth 51.2 % SL in older males, 6-7 teeth on second pharyngobranchial in larger specimens, 27-30 vertebrae, posterior border of the dorsal and anal fins black in males, a black bar on parietal series of neuromasts, dorsal and anal-fin bases with elongated white spots, anterior flank bars about so wide as interspace and posterior bars wider.

Description

Morphometric data appear in Table 8. Males larger than females, largest male examined 46.5 mm SL, largest female 39.9 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 male. 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 4th and 8th anal-fin rays in males, and between anus and urogenital papilla in females. Tip of both pelvic fins reaching between base of 2nd and 6th anal-fin rays. Medial pelvic-fin membranes 30-50 % coalesced. Urogenital papilla not attached to anal fin. Dorsal-fin origin on vertical between base of 1st and 3rd anal-fin rays in males, slightly anterior to anal-fin origin in females, anal-fin origin through base of 2nd or 3rd dorsal-fin ray in females; dorsal-fin origin between neural spines of 8th 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 10th vertebrae in females. Dorsal-fin rays 20-25 in males, 18-22 in females; anal-fin rays 23-28 in males, 21-26 in females; caudal-fin rays 21-25; pectoral-fin rays 11-12; pelvicfin 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 F-, 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 12-14; scale rows around caudal peduncle 16-18. Three to seven minute contact organs on each scale of ventral portion of flanks in males. Rows of minute contact organs on one or two uppermost pectoral-fin rays in males. No contact organ on anal, dorsal and caudal fins.

Cephalic neuromasts: supraorbital 16-21, parietal 3-4, anterior rostral 1, posterior rostral 1, infraorbital 2-3 + 22-30, preorbital 1-3, otic 2-4, post-otic 3-5, supratemporal 1, median opercular 1, ventral opercular 1-2, preopercular plus mandibular 30-37, lateral mandibular 4-7.

Basihyal subtriangular, width about 55-65 % of length; basihyal cartilage long, about 55-65 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Four to seven teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3-4 + 9-10. Dermosphenotic ossification absent. Ventral process of posttemporal long or short. Total vertebrae 27-30.

Coloration

Males: sides of body light blue to pale golden, with 7-14 bars, of which anterior bars black to gradually dark purplish brown posteriorly; anterior bars narrow, about as wide as interspace, posterior bars slightly wider than interspace; usually an 8-shaped black spot on posterior part of caudal peduncle. Urogenital papilla gray. Opercular and infraorbital regions light bluish green; black infraorbital bar, wider close to eye, gradually narrowing ventrally; elongate subtriangular black supraorbital bar, with narrow distinctive extension over neuromast parietal series. Iris dark yellow, with dark brown bar through center of eye. Unpaired fins dark gray, with white small spots, elongated on dorsal and anal-fin bases; dorsal and anal fins with black posterior margin; pale blue iridescence on distal portion of anal fin; sometimes pink to golden iridescence on distal portion of dorsal fin. Pelvic fins dark bluish gray. Pectoral fins hyaline with black ventral margin.

Females: sides of body light yellowish brown, with pale gray bars or vertical rows of elongate gray spots, sometimes gray marks inconspicuous; venter pale golden; rarely one to three black spots on anterocentral portion of flank; two black spots vertically arranged on posterior portion of caudal peduncle, often coalesced to form an 8-shaped spot. Opercular region pale greenish golden. Iris light yellow, with gray bar through center of eye. Infraorbital and supraorbital bars dark gray. Unpaired fins hyaline, with small dark gray spots; paired fins hyaline.

Distribution

Southern laguna dos Patos floodplains and adjacent coastal plains, Rio Grande do Sul, southern Brazil (Fig. 52).