Austrolebias vandenbergi

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 : 111-113

Austrolebias vandenbergi (Huber)

(Fig. 43)

Cynolebias bellottii non C. bellottii Steindachner; Ringuelet et al., 1967: 439 (misidentification of specimens from northern Argentina).

Cynolebias vandenbergi Huber, 1995: 7 ( type locality: Province of Presidente Hayes, near Fortin Toledo , Paraguay, 22.27 S, 60.54 W; holotype: ZMA 121270 ).

Material examined

Paraguay: Presidente Hayes: UFRJ 3028 , 2 paratypes; near Fortin Toledo ; W. Leen & A. Van den Berg, 23 Jul. 1993. UFRJ 3029 , 4 paratypes (c&s); 25 km N from Faro Moro to Montania ; L. Van den Berg, 1994. Argentina: Salta: ILPLA 994 , 5 (2 c&s); Salta ; S. Perotti, 19 Mar. 1951. Salta: ILPLA 992 , 3; Luna Muerta, San Martin ; S. Pierotti, 12 Dec. 1945. ILPLA 998 , 10; Luna Muerta ; S. Pierotti, 6 Aug. 1945. ILPLA 995 , 27 (3 c&s); San Martin ; S. Pierotti, 21- 26 Mar. 1950. MCMI 1018 , 2; Ruta B1, Poste 307, Hickman, San Martin ; Gonzo-Fabrezi, 19 Dec. 2004. Formosa: MLP 8281 , 1; Ingeniero Juarez ; A. Bachmann, no date. Corrientes: ILPLA 993 , 1; Ituzaingó; S. Pierotti & O. Budin, 16 Nov. 1950. MCMI 920 , 1; Ruta Nacional 81, Hickman, General de San Martin ; M. Fabrezi, 17 Dec. 2003. MCMI 925 , 2; Ruta Nacional 81, General de San Martin ; G. Gonzo & M. Fabrezi, 3 Mar. 2004. MCNI 1142 , 1; Ruta Provincial 52, General de San Martin ; G. Gonzo & M. Fabrezi, 13 Apr. 2005.

Diagnosis

Differs from all species of the A. bellottii group by having transverse rows of scales on anal-fin base in males, prominent papillate contact organs on rays of anterior half of anal fin in males, and 5 + 14-16 gill-rakers on first branchial arch. Also distinguished from all other species of the A. bellottii group by the following combination of features: urogenital papilla not attached to anal fin, dorsal-fin origin posterior to anal-fin origin in males, flanks light bluish gray to pale golden with narrow faint gray bars in males, anal-fin rays 29 -31 in males, 27-29 in females, longitudinal series scales 31-33, frontal squamation H- patterned, and vertebrae 31-33.

Description

Morphometric data appear in Table 7. Males larger than females, largest male examined 99.4 mm SL, largest female 52.3 mm SL. Dorsal profile approximately straight to slightly concave on head, convex from nape to end of dorsal-fin base, nearly straight on caudal peduncle; sometimes adipose ridge on frontal region in males. Ventral profile convex from lower jaw to end of anal-fin base, approximately 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 6th anal-fin rays in males, and through urogenital papilla in females. Tip of each pelvic fin reaching between base of 1st and 3rd anal-fin ray. Medial pelvic-fin membranes about 75 % coalesced. Base of urogenital papilla attached to anal fin in males. Dorsal-fin origin on vertical between base of 2nd and 4th anal-fin rays in males, through base of 1st anal-fin ray in females, sometimes slightly anterior to anal-fin origin; dorsal-fin origin between neural spines of 9th and 11th vertebrae in males, between neural spines of 11th and 13th vertebrae in females. Anal-fin origin between pleural ribs of 8th and 9th vertebrae in males, between pleural ribs of 8th and 10th vertebrae in females. Dorsal-fin rays 21-28 in males, 19-24 in females; anal-fin rays 27-33 in males, 23-30 in females; caudal-fin rays 23-27; pectoral-fin rays 11-13; pelvic-fin rays 5.

Scales large and cycloid. Trunk and head entirely scaled, except ventral surface of head. Three to five rows of scales on anal-fin base, no scales on dorsal-fin base, and three rows of scales on caudal-fin base. Frontal squamation H-patterned; E-scales not overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 31-33; transverse series of scales 13-14; scale rows around caudal peduncle 16. Row of three to five prominent contact organs on each scale of flanks and opercular region in males. Row of prominent contact organs on four uppermost pectoral-fin rays, and distal portion of anal-fin rays in males. No contact organ on dorsal and caudal fins.

Cephalic neuromasts: supraorbital 20-23, parietal 5, anterior rostral 2, posterior rostral 1, infraorbital 3 + 31, preorbital 2, otic 3, post-otic 3, supratemporal 1, median opercular 1, ventral opercular 3, preopercular 31, mandibular 18, lateral mandibular 5.

Basihyal nearly triangular, width about 75 % of length; basihyal cartilage long, about 75 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Eleven to thirteen teeth on second pharyngobranchial. Gill-rakers on first branchial arch 5 + 14-16. Often two minute dermosphenotic ossifications. Ventral process of posttemporal long. Total vertebrae 31-33.

Coloration

Males: sides of body bluish gray to pale golden, with 12-18 faint gray bars. Sides of head gray to blue on opercular and infraorbital region; approximately rectangular dark gray infraorbital bar; subtriangular dark gray supraorbital bar, not extending to parietal series of neuromasts. Iris yellow, with black bar through center of eye. Dorsal fin dark bluish gray, with white dots on basal half, often with pink iridescence. Anal fin dark bluish gray, often with light blue iridescence. Caudal fin dark bluish gray, marginal region hyaline. Pelvic fins dark bluish gray. Pectoral fins hyaline, with dark bluish gray ventral margin.

Females: sides of body light yellowish brown, with vertically elongate dark gray spots, often forming bars; usually one or two black spots on anterocentral portion of flanks; venter pale yellow. Opercular region pale greenish blue. Pale gray supraorbital and infraorbital bars. Iris light yellow, with gray bar through center of eye. Unpaired fins hyaline, with dark gray small spots, darker and elongated on dorsal portion of dorsal and anal fins; paired fins hyaline.

Distribution

Río Paraguay-Paraná basin in Paraguay and northern Argentina (Fig. 11).