Austrolebias charrua

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 : 120-123

Austrolebias charrua Costa & Cheffe

(Fig. 46)

Cynolebias adloffi non C. adloffi Ahl; Vaz-Ferreira & Melgarejo, 1984: 43 (misidentification of specimens from Chuy and San Miguel, Rocha, Uruguay).

Austrolebias charrua Costa & Cheffe, 2001: 182 ( type locality: temporary lagoon close to arroio Chui , road to Barra do Chui , Rio Grande do Sul, Brazil; holotype: MZUSP 60070 ).

Cynolebias reicherti Loureiro & García, 2004: 16 ( type locality: temporary pool 300 m east from route 18, 1 km north of Vergara city , approximately 32°55’S 53°54’W, southwestern laguna Merín basin, Departamento de Treinta y Tres, Uruguay; holotype: ZVC-P 4362 ).

Material examined

Brazil: Rio Grande do Sul: laguna dos Patos system: MZUSP 60070 , holotype, male, 47.2 mm SL; MZUSP 60071 , 5 paratypes; UFRJ 4950 , 47 paratypes; UFRJ 5061 , 7 paratypes (c&s); temporary pool close to arroio Chui , road to Barra do Chui ; W. J. E. M. Costa & A. C. Bacellar, 12 Sept. 1999. MCP 28027 , 16 paratypes; UFRJ 4990 , 69 paratypes; UFRJ 5009 , 42 paratypes; UFRJ 5024 , 4 paratypes; temporary swamp, km 5.5 of the road between Chui and Barra do Chui ; W. J. E. M. Costa & A. C. Bacellar, 12 Sept. 1999. UFRJ 5006 , 10 paratypes; temporary pool, 3 km N of Chui , road BR-471 ; W. J. E. M. Costa & A. C. Bacellar, 12 Sept. 1999. - UFRJ 4948 , 43; ditch at road side, km 3 of the road between Chui and Barra do Chui ; W. J. E. M. Costa & A. C. Bacellar, 11 Sep. 1999. UFRJ 5008 , 9; temporary pool, Chui ; W. J. E. M. Costa & A. C. Bacellar, 11 Sep. 1999. UFRJ 5034 , 77; UFRJ 5035 , 5 (c&s); temporary pool 2 km N of Curral Alto ; W. J. E. M. Costa & A. C. Bacellar, 14 Sep. 1999. UFRJ 4723 , 38; UFRJ 4724 , 8 (c&s); temporary pool, road between Chui and Barra do Chui ; W. J. E. M. Costa et al., 19 Jul. 1998. Uruguay: Rocha: CIMC 3542 , 16 paratypes; temporary swamp close to arroyo San Miguel, Chuy ; M. Cheffe & G. Maurício, 30 Aug. 2000. CTL 1395 , 100; temporary swamp near canal Andreoni, Ruta 14, km 504 , 33°55.21’S 53°32.61’W; P. Laurino et al., 27 Aug. 2004. UFRJ 6172 , 4; UFRJ 6173 , 4 (c&s); CTL 1457 , 15; Ruta 14, km 269, north to Lascano , 33°27.28’S 54°18.06’W; P. Laurino et al., 28 Aug. 2004. UFRJ 6174 , 2; CTL 1469 , 8; Ruta 14, km 270, near rio Cebollati , north to Lascano , 33°36.82’S 54°18.00’W; P. Laurino et al., 28 Aug. 2004. UFRJ 4459 , 18; between 18 de Julio and San Luis, Ruta 19 ; J. J. Reichert, no date. Treinta y Tres: UFRJ 6175 , 6; CTL 1521 , 34; swamp at arroyo Yerbal , 33°13.30’S 54°23.93’W; P. Laurino et al., 28 Aug. 2004.

Diagnosis

Distinguished from the 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 or posterior in females, 23-29 anal-fin rays in males and 20-25 in females, 23-26 caudal-fin rays, maximum body depth 45.1 % SL in older males, 2-5 teeth on second pharyngobranchial in larger specimens, 29-31 vertebrae, no distinctive black mark on posterior portion of the dorsal and anal fins in males, no distinctive black mark on parietal series of neuromasts, dorsal and anal-fin bases with white dots, anterior flank bars about so wide as interspace and posterior bars wider.

Description

Morphometric data appear given in Table 8. Males larger than females, largest male examined 47.2 mm SL, largest female 41.5 mm SL. Dorsal profile convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle; often 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 8th anal-fin rays in males, between urogenital papilla and base of 2nd anal-fin ray in females. Tip of each pelvic fin reaching between base of 3rd and 5th anal-fin rays. Medial pelvic-fin membranes 20-50 % coalesced. Urogenital papilla not attached to anal fin. Dorsal-fin origin on vertical between base of 1st and 4th anal-fin rays in males; dorsalfin base slightly anterior to anal-fin origin or slightly posterior to origin in females; dorsalfin origin between neural spines of 8th and 10th vertebrae in males, between neural spines of 9th and 12th vertebrae in females. Anal-fin origin between pleural ribs of 8th and 10th vertebrae in both sexes. Dorsal-fin rays 21-26 in males, 16-22 in females; anal-fin rays 23 -29 in males, 20-25 in females; caudal-fin rays 23-26; 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 usually F-patterned, rarely G-patterned; E- scales slightly overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 27-30, scales regularly arranged; transverse series of scales 12-14; scale rows around caudal peduncle 16. Three to seven minute contact organs on each scale of ventral portion of flanks in males. Row of small contact organs on two or three uppermost pectoral-fin rays, sometimes on distal portion of five anteriormost rays of anal fin in males. No contact organ on dorsal and caudal fins.

Cephalic neuromasts: supraorbital 15-22, parietal 1-4, anterior rostral 1, posterior rostral 1, infraorbital 2-3 + 22-27, preorbital 2-3, otic 2-3, post-otic 3-4, supratemporal 1, median opercular 1, ventral opercular 1-2, preopercular plus mandibular 29-40, lateral mandibular 4-6.

Basihyal subtriangular, width about 55-60 % of length; basihyal cartilage long, about 45-55 % 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 + 10-11. Dermosphenotic ossification absent. Ventral process of posttemporal long or short. Total vertebrae 29-31.

Coloration

Males: sides of body bluish silver, with 8-15 brown to dark gray bars, anterior bars slightly narrower than interspace, posterior bars wider than interspace, sometimes caudal peduncle dark brown with vestiges of light bars; sometimes a black spot on anterocentral portion of flanks; usually an 8-shaped black spot on posterior portion of caudal peduncle. Urogenital papilla gray. Opercular and infraorbital region light blue; black infraorbital bar, wider close to eye, gradually narrowing ventrally; subtriangular black supraorbital bar, sometimes abutting neuromast parietal series, but not forming a distinctive transverse bar. Iris dark yellow, with dark brown bar through center of eye. Unpaired fins dark gray, with small white spots, sometimes slightly elongated on fin near dorsal and anal fin bases; sometimes dorsal and anal fin with narrow dark gray posterior border; 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; sometimes one to three black spot on anterocentral portion of flank; two black spots vertically arranged on posterior portion of caudal peduncle, often coalesced to form an 8-shaped spot, sometimes minute or absent. Opercular region pale blue. 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 lagoa Mirim basin and adjacent coastal plains, southern Brazil and northeastern Uruguay (Fig. 52).

Remarks

Loureiro & García (2004) described C. reicherti , based on material collected both in the río Cebollatí drainage (holotype and paratypes) and in the río Tacuarí drainage (paratypes). Loureiro & García (2004) compared C. reicherti to A. adloffi , but no mention was made of A. charrua , A. minuano , or A. nigrofasciatus , which occur in the same region and which were described three years before. Examination of specimens collected in the drainage ( río Cebollatí) which includes the type locality of C. reicherti shows it to be indistinguishable from A. charrua , whereas material from the río Tacuarí drainage represents a new species, described later in the present paper as A. salviai , and which is hypothesized to be more closely related to A. adloffi , A. nigrofasciatus and A. nachtigalli than to A. charrua . In a recent molecular analysis, García (2006) considered C. reicherti as the sister group to a clade including A. arachan , A. charrua and A. nigrofasciatus , a hypothesis not in agreement with the present analysis.