Austrolebias nonoiuliensis

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 : 41-43

Austrolebias nonoiuliensis (Taberner, Fernandez & Castelli)

(Fig. 16)

Cynolebias nonoiuliensis Taberner, Fernandez & Castelli, 1974: 187 ( type locality: charcos temporarios in Nueve de Julio , provincia de Buenos Aires, Argentina; holotype: MACN 6754-5 ).

Material examined

Argentina: Buenos Aires: MACN 6754-5 , male holotype, 77.0 mm SL; MACN 6755- 7 , one paratype; MACN 6754 , 12 paratypes; MACN 6755 , 17 paratypes; ZFMK 13259- 60 , 2; Nueve de Julio ; Taberner, Fernadez & Castelli, 1 Nov. 1973. ZFMK 12048-72 , 25 (2c&s); same locality ; Lüling, 30 Sep. 1978.

Diagnosis

Distinguished from all other species of the A. robustus group by the following combination of features: dorsal-fin origin on vertical between base of 4th and 7th anal-fin rays in males, between base of 1st and 4th anal-fin rays in females; longitudinal series scales 31-35; vertebrae 33-34; flank gray in males; spots and bars on flank and one or two large, round dark gray to black spot on caudal peduncle end in females.

Description

Morphometric data appear in Table 2. Males larger than females, largest male examined 77.0 mm SL, largest female 42.6 mm SL. Dorsal profile of head slightly concave, convex from nape to end of dorsal-fin base, approximately straight on caudal peduncle; 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. Body moderately deep, 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 rounded. Pectoral fins elliptical, posterior margin on vertical between base of 2nd and 4th anal-fin rays in male, between anus and base of 1st anal-fin ray in female. Tip of each pelvic fin reaching between base of 3rd and 4th anal-fin rays in males, between urogenital papilla and base of 3rd anal-fin ray in females. Pelvic-fin bases medially united, medial pelvic-fin margins about 25 % united. Urogenital papilla not attached to anal fin. Dorsal-fin origin on vertical between base of 4th and 7th anal-fin rays in males, between base of 1st and 4th anal-fin rays in females; dorsal-fin origin between neural spines of 12th and 13th vertebrae in males, between neural spines of 11th and 12th vertebrae in females. Anal-fin origin between pleural ribs of 11th and 12th vertebrae in males, between pleural ribs of 10th and 11th vertebrae in females. Dorsal-fin rays 22-24 in males, 18-21 in females; anal-fin rays 25-29 in males, 22-25 in females; caudal-fin rays 28-32; pectoral-fin rays 12-13; pelvicfin rays 6.

Scales large and cycloid. Trunk and head entirely scaled, except ventral surface of head. A few scales scattered sparsely over anal-fin base; no scales on dorsal-fin base; three rows of scales on caudal-fin base. Frontal squamation F-patterned; E-scales not overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 33-34, scales regularly arranged; transverse series of scales 13-15; scale rows around caudal peduncle 20-22. One prominent contact organ on each scale of flank and opercle in males. Rows of prominent contact organs on anal-fin rays; no contact organs on dorsal fin and caudal fin; row of contact organs on four uppermost pectoral-fin rays in males.

Cephalic neuromasts: supraorbital 17-23, parietal 2, anterior rostral 1, posterior rostral 1, infraorbital 3 + 24-26, preorbital 3, otic 5-7, post-otic 5-6, supratemporal 1, median opercular 1, ventral opercular 2, preopercular plus mandibular 36-49, lateral mandibular 5.

Basihyal subtriangular, width about 85 % of length; basihyal cartilage long, about 60 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Five teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3 + 11. Dermosphenotic ossification absent. Ventral process of posttemporal long. Total vertebrae 31-35.

Coloration

Males: side of body bluish gray; juveniles with faint light brown vertical bars and dark gray round spot on posterodorsal portion of caudal peduncle. Urogenital papilla dark gray. Opercular and infraorbital regions pale green; approximately rectangular gray infraorbital bar, faint gray supraorbital bar. Iris yellow, with brown bar through center of eye. Fins dark bluish gray.

Females: sides of body light yellowish brown, with vertically elongated dark gray spots, sometimes forming short bars above anal fin; no distinctively darker spot on anterocentral portion of flank; often one, sometimes two, dark gray to black spots on posterior portion of caudal peduncle. Opercular region pale greenish golden. Iris yellow, with gray bar through center of eye. Faint infraorbital and supraorbital gray bars. Unpaired fins hyaline, with small dark gray spots; paired fins hyaline.

Distribution

Upper río Salado drainage, lower río de La Plata basin, northeastern Argentina (Fig. 8).

Remarks

Within the controversial historical context about names of Argentinean annual fish species (see history above), Taberner et al. (1974) described Cynolebias nonoiuliensis , from Buenos Aires Province. It was considered a valid species by all authors prior to 1995, when Wildekamp relegated it to the synonymy of C. holmbergi Berg, a species previously considered a synonym of C. elongatus (Lazara, 1981, 1984; Costa, 1995). This taxonomic decision was based solely on a collection of specimens similar to C. nonoiuliensis from the vicinity of the type locality of C. holmbergi by two Spanish aquarists. However, recent examination of the types of C. holmbergi reveals that it is a synonym of M. elongatus (see below). Cynolebias nonoiuliensis was considered a valid species by Costa (1998a), who transferred it to Austrolebias .