Austrolebias cheradophilus, Wilson J. E. M. Costa, 2006

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 : 44-47

Austrolebias cheradophilus (Vaz-Ferreira, Sierra-de-Soriano & Scaglia-de-Paulete), new combination

(Fig. 17)

Cynolebias cheradophilus Vaz-Ferreira, Sierra-de-Soriano & Scaglia-de-Paulete, 1964: 14 ( type locality: temporary swamp near arroyo Valizas , 34º26’S 53°26’W, Departamento de Rocha, Uruguay; holotype: ZVC-P 522 ).

Material examined

Uruguay: Rocha: UFRJ 6165 , 4; UFRJ 6166 , 3 (c&s); CTL 1384 , 14; temporary pool near Ruta 9, km 254.8 , 34°13.23’S 53°57.26’W; P. Laurino et al., 27 Aug. 2004. UFRJ 4458 , 2 (c&s); Ruta 10, close to arroyo Valizas ; J. Reichert, no date.

Diagnosis

Distinguished from all other congeners by the drastic reduction of scales, which are small and not overlapping, and which are restricted to the median portion of flank and opercle; pelvic fins separated by wide interspace; and broad urogenital papilla in males.

Description

Morphometric data appear in Table 3. Males larger than females; largest male examined 69.8 mm SL, largest female 46.7 mm SL. Dorsal profile convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle; accentuated declivity on anterior portion of frontal region; no distinctive adipose ridge on frontal region. 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 or just anterior to it. Body moderately deep and slightly compressed. Snout blunt and jaws short.

Tip of both dorsal and anal fin rounded. Anteromedian rays of anal fin of female not lengthened; distal portion of anal fin thickened in female. Caudal fin subtruncate in male, rounded in female. Pectoral fins rounded and short, posterior margin on vertical through urogenital papilla. Pelvic fins narrow, separated by wide interspace about twice pelvic-fin base width. Tip of each pelvic fin reaching between base of 2nd and 3rd anal-fin rays. Urogenital papilla robust and conical in male, not attached to anal fin. Dorsal-fin origin on vertical between base of 2nd and 3rd anal-fin rays; dorsal-fin origin between neural spines of 12th and 14th vertebrae in males, between neural spines of 14th and 16th vertebrae in females. Anal-fin origin between pleural ribs of 10th and 11th vertebrae in males, between pleural ribs of 13th and 15th vertebrae in females. Dorsal-fin rays 18-22 in males, 16-19 in females; anal-fin rays 19-23 in males, 18-20 in females; caudal-fin rays 29-31; pectoral-fin rays 13-14; pelvic-fin rays 3-5.

Scales minute and thin, not overlapping; cycloid. Squamation on trunk and head extremely reduced, restricted to scales concentrated on median portion of flank, and few scales scattered over opercle; no scales on dorsum, dorsal portion of head and flank, venter, ventral portion of head and flank, and fins. Longitudinal series of scales with about 70 scales, irregularly arranged. One prominent contact organ on each scale of flank and opercle in males. Row of prominent contact organs on inner surface of all pectoral-fin rays, except two ventralmost rays, and on lateral surface of all anal-fin rays, except last three. No contact organ on dorsal and caudal-fin rays.

Cephalic neuromasts: supraorbital 19-21, parietal 2-3, anterior rostral 2, posterior rostral 1, infraorbital 2-4 + 21, preorbital 1, otic plus post-otic 11-13, supratemporal 1-2, median opercular 1, ventral opercular 2, preopercular plus mandibular 35-41, lateral mandibular 3-5.

Basihyal subtriangular, wider than long in males, width about 70 % of length in females; basihyal cartilage short, about 30 % of total basihyal length, without lateral projections. Six branchiostegal rays. Second pharyngobranchial teeth absent. Gill-rakers on first branchial arch 3-5 + 11-12. Dermosphenotic ossification absent. Ventral process of posttemporal short. Total vertebrae 34-36.

Coloration

Males: side of body dark brownish gray, with 11-14 narrow pale golden bars; posterior bars sometimes substituted by vertical rows of vertically elongated spots. Urogenital papilla dark gray. Opercular and infraorbital regions pale greenish blue; approximately rectangular, elongate black infraorbital bar; dark gray supraorbital spot, united to dark gray zone on posterior portion of frontal region. Iris brown, with black bar through center of eye. Unpaired fins dark gray, basal portion black with white dots; pink iridescence on distal portion of dorsal fin and blue iridescence on distal portion of anal fin. Pelvic fins dark gray. Pectoral fins hyaline.

Females: sides of body light brown, with vertically elongated dark gray spots, often forming bars; no darker spot on anterocentral portion of flank or caudal peduncle. Opercular region pale golden. Iris yellow, with dark gray bar through center of eye. Faint infraorbital gray bar and supraorbital gray spot. Unpaired fins hyaline, with small dark gray spots on fin bases; paired fins hyaline.

Distribution

Isolated coastal drainages of southeastern Uruguay (Fig. 18).