Austrolebias duraznensis

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 : 74-77

Austrolebias duraznensis ( García, Scvortzoff & Hernández)

(Fig. 30)

“ Cynolebias duraznensis n. sp. ” DYU-11/91” Reichert, 1992: 59 ( nomem nudum).

Cynolebias duraznensis García, Scvortzoff & Hernández, 1995: 107 ( type locality: Durazno , Uruguay; no type specimen designated or mentioned ).

Material examined

Uruguay: Durazno: UFRJ 6192 , 3 (c&s); CTL 969 , 12; Paso de San Borja , 33°24.95’S 56°25.95’W; P. Laurino, T. Litz, E. Perujo, R. Recuero, H. Salvia & J. Salvia, 22 Aug. 2004. Soriano: UFRJ 6193 , 4; UFRJ 6194 , 3 (c&s); CTL 1162 , 34; Parque Guernika, Mercedes , 33°14.73’S 58°03.12’W; no data on collectors and date.

Diagnosis

Similar to A. affinis and A. juanlangi and distinguished from all other species of the A. alexandri group by the posterior margin of the pectoral fin in males reaching a vertical between urogenital papilla and base of second anal-fin ray (vs. between base of second and fifth anal-fin rays). It is distinguished from A. juanlangi in having blue bars substituted by vertical rows of blue dots, except sometimes narrow ill-defined bars on anteriormost portion of flank (vs. well-defined bright blue bars on flanks in males), and more neuromasts in the preopercular (18-21 vs. 15-18) and mandibular series (11-13 vs. 9-10). Differs from A. affinis by having fewer neuromasts in infraorbital series (2 + 22-23, vs. 2 + 25-27) and light dots of unpaired fins in male restricted to basal portion of fins (vs. over the entire fins). According to García et al. (1995), A. duraznensis is also distinguishable from A. affinis by karyotypic features (6 subteleocentric and 38-40 acrocentric elements, vs. no subteleocentric and 44-45 acrocentric elements).

Description

Morphometric data appear given in Table 5. Males larger than females, largest male examined 28.1 mm SL, largest female 21.1 mm SL. Dorsal profile nearly straight to convex on head, convex from nape 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 slender and compressed. Snout blunt and jaws short.

Tip of both dorsal and anal fins rounded. Anteromedian rays of anal fin of females not lengthened; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fins rounded, posterior margin on vertical between pelvic-fin base and base of 2nd anal-fin ray in males, on vertical between pelvic-fin base and anus in females. Tip of each pelvic fin reaching between base of 2nd and 3rd anal-fin rays in males, between urogenital papilla and base of 1st anal-fin ray in females. Pelvic-fin bases united or in close proximity, medial membrane never coalesced. Urogenital papilla not attached to anal fin. Anal-fin origin on vertical between bases of 1st and 3rd dorsal-fin rays; dorsal-fin origin between neural spines of 7th and 9th vertebrae in males, between neural spines of 10th and 12th vertebrae in females. Anal-fin origin between pleural ribs of 8th and 9th vertebrae in males, between pleural ribs of 10th and 12th vertebrae in females. Dorsal-fin rays 22-27 in males, 16-18 in females; anal-fin rays 22-24 in males, 18-20 in females; caudal-fin rays 24-27; pectoral-fin rays 11; pelvic-fin rays 5.

Scales large and cycloid. Trunk and head entirely scaled, except ventral surface of head. No scales on dorsal and anal-fin bases, and two rows of scales on caudal-fin base. Frontal squamation H-patterned; E-scales overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 27-28, scales regularly arranged; transverse series of scales 12; scale rows around caudal peduncle 16. One contact organ on each scale of ventral portion of flank and opercle in males. Row of minute contact organs on two uppermost pectoral-fin rays in males, sometimes absent; no contact organs on unpaired fins.

Cephalic neuromasts: supraorbital 15-18, parietal 1 or none, anterior rostral 1, posterior rostral 1, infraorbital 1-2 + 22-23, preorbital 2, otic 3, post-otic 4, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 18-21, mandibular 12-13, lateral mandibular 4.

Basihyal subtriangular, width about 70 % of length; basihyal cartilage moderate in length, about 45 % of total basihyal length, without lateral projections. Six branchiostegal rays. One to three teeth on second pharyngobranchial. Gill-rakers on first branchial arch 2-3 + 8-9. Dermosphenotic ossification absent. Ventral process of posttemporal vestigial. Total vertebrae 27-29.

Coloration

Males: sides of body dark bluish gray to dark brown, with 9-11 rows of bright blue dots; sometimes dots of anteriormost rows united and forming narrow vertical lines in larger males. Urogenital papilla gray. Opercular and infraorbital regions bright blue; approximately rectangular, dark gray to black infraorbital bar; subtriangular dark gray to black supraorbital blotch, not reaching neuromast parietal series. Iris brown, with black bar through center of eye. Unpaired fins dark gray, with light blue to white dots concentrated on basal two thirds of fins, usually irregularly arranged on dorsal and caudal fins, often arranged in two transverse rows on anal fin; blue iridescence on distal portion of dorsal fin; intense bright blue iridescence on distal portion of anal fin, often forming distinctive stripe; bright blue iridescence on distal portion of caudal fin. Pelvic fins dark bluish gray with light blue basal spot. Pectoral fins dark bluish gray, with bright blue iridescence.

Females: sides of body light yellowish brown, with dark gray spots, usually as so large as eye, vertically elongated, sometimes forming short bars above anal fin; sometimes 1 or 2 black spots on anterocentral portion of flank and 1 or 2 on caudal peduncle; venter pale golden. 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 dark gray spots, darker and elongated on basal portion; paired fins hyaline.

Distribution

Lower río Negro basin, southwestern Uruguay (Fig. 20).

Remarks

Since the species name duraznensis was first cited by Reichert (1992) in quotation marks, and was not accompanied by any diagnostic features, it thus constitutes a nomen nudum (Costa, 1995). García et al. (1995), in a comparative study on karyotypes of Uruguayan cynolebiatines, used the name C. duraznensis . This species was then diagnosed by karyotypic features and compared to other congeners, making the name C. duraznensis available for nomenclatural proposes (Costa, 2002b). As indicated above in the synonymy, therefore, the name should properly date from “ García, Scvortzoff & Hernández, 1995.”