Austrolebias bellottii

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 : 104-108

Austrolebias bellottii (Steindachner)

(Figs. 40-41)

Cynolebias bellottii Steindachner, 1881: 98 ( type locality: La Plata , Argentina; holotype: NMW 75105 ).

Cynolebias maculatus Steindachner, 1881: 98 ( type locality: La Plata , Argentina; holotype: NMW 59613 ).

Cynolebias gibberosus Berg, 1897: 294 ( type locality: Cachari , Partido de Azul , Provincia de Buenos Aires, Argentina; lectotype: MACN 5172 , herein designated).

Cynolebias irregularis Ahl, 1938: 57 (based on aquarium material of unknown geographic origin, probably Argentina according to the author; holotype: ZMB 21145 ).

Material examined

Argentina: Buenos Aires: NMW 75105 (photo), male holotype, about 47.5 mm SL; NMW 59613 (photo), female holotype of C. maculatus , about 50.0 mm SL; La Plata ; no data on collector and date. MACN 5172 , male lectotype of C. gibberosus , about 70 mm SL; MACN 5177 , female paralectotype of C. gibberosus , about 50 mm SL; Cachari , Azul ; J. Monguillot, Feb. 1896. MLP 6847 , 1; Punta Lara ; C. Tremouilles, 1960. MLP 3091 , 6; El Tunel, La Plata ; no data on collection, Oct. 1941. MLP 1075 , 1; MLP 1076 , 1; MLP 1077 , 1; La Plata floodplains ; no data on collection. MLP 3643 , 3; La Plata ; R. S. Castillo, Oct. 1936. MNRJ 9753 , 3; near La Plata ; H. Lopez, R. Vaz-Ferreira, B. Sierra & J. Soriano, 3 Nov. 1962. MNRJ 11350 , 2; Punta Lara ; R. Vaz-Ferreira & B. Sierra, 2 Nov. 1962. MLP 8298 , 4; San Miguel del Monte ; A. Bachmann, Sep. 1963. MLP 8304 , 3; Tigre, rio Lujan floodplains ; A. Bachmann, 30 Nov. 1952. MCP 11595 , 5; swamp in Florencio Varela ; L. Braga, 1 Nov. 1986. MLP 8299 , 7; Buenos Aires ; A. Bachmann, 27 Mar. 1953. ILPLA 997 , 9 (2 c&s); Las Heras, rio Salado basin ; A. Aon, 5 Dec. 1980. UFRJ 5156 , 14; UFRJ 5160 , 6 (c&s); swamp on the road Ruta Nacional 11, coming from Magdalena ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 7 Sep. 1998. UFRJ 4747 , 30; swamp close to Base Aeronaval de Punta Indio ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 7 Sep. 1998. UFRJ 4746 , 8; temporary pool, road Ruta 11, between Punta Indio and Veronica ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 7 Sep. 1998. UFRJ 4745 , 14; road Ruta Provincial 36, near Pipinas ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 7 Sep. 1998. UFRJ 5158 , 20; swamp, road Ruta Provincial 29, km 6 of the section Brandsen-Ranchos ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 8 Sep. 1998. UFRJ 5161 , 24; UFRJ 5162 , 6 (c&s); small road 10 km of the road Ruta Provincial 29, between General Belgrano and Chas ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 8 Sep. 1998. UFRJ 4744 , 6; road Ruta Provincial 29, between General Belgrano and Ranchos ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 8 Sep. 1998. UFRJ 4741 , 50; UFRJ 4742 , 6 (c&s); km 276, road Ruta Nacional 2, near arroyo Vivorata ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 9 Sep. 1998. UFRJ 4738 , 19; small road 13 km of the road Ruta Nacional 2, near arroyo Vivorata ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 9 Sep. 1998. UFRJ 5163 , 5; temporary pool, road between Villa Elisa and Punta Lara ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 10 Sep. 1998. UFRJ 4743 , 4; temporary pool, road Ruta Nacional 11, between Magdalena and La Plata ; W. J. E. M. Costa, A. Miquelarena, L. Protogino & R. Filiberto, 10 Sep. 1998.

Diagnosis

Distinguished from all other species of the A. bellottii group by the following combination of features: no prominent contact organ on anal fin in males, urogenital papilla attached to anal fin in males, dorsal-fin origin posterior to anal-fin origin in males, flank dark blue to dark green with vertical rows of light blue dots in males, anal-fin rays 25-28 in males, 21-25 in females, longitudinal series scales 26-29, frontal squamation H or G-patterned, vertebrae 27-31, anal-fin origin between pleural ribs of 7th and 10th vertebrae in males, between pleural ribs of vertebrae 9th and 11th in females, and numerous teeth (8-12) on second pharyngobranchial.

Description

Morphometric data appear in Table 7. Males larger than females, largest male examined 70.0 mm SL, largest female 39.4 mm SL. Dorsal profile slightly concave on head, convex from nape to end of dorsal-fin base, nearly straight on caudal peduncle; often 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 nearly triangular; distal portion of anal fin thickened in females. Caudal fin rounded. Pectoral fins elliptical, posterior margin on vertical between base of 4th and 7th anal-fin rays in males, and between urogenital papilla and base of 2nd anal-fin ray in females. Tip of both pelvic fins reaching between base of 2nd and 4th anal-fin rays. Medial pelvic-fin membranes about 60-75 % coalesced. Entire urogenital papilla attached to anal fin in males. Dorsal-fin origin on vertical between base of 4th and 5th anal-fin rays in males, between base of 1st and 3rd anal-fin rays in females; dorsal-fin origin between neural spines of 8th and 10th vertebrae in males, between neural spines of 11th and 12th vertebrae in females. Anal-fin origin between pleural ribs of 7th and 9th vertebrae in males, between pleural ribs of 9th and 11th vertebrae in females. Dorsal-fin rays 20-27 in males, 17-21 in females; anal-fin rays 26-32 in males, 24-29 in females; caudal-fin rays 24-27; pectoral-fin rays 11-13; pelvic-fin 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 G-patterned, sometimes H or F- patterned; E-scales not or slightly overlapping medially; scales arranged in transverse pattern. Longitudinal series of scales 28-30; transverse series of scales 13-17; scale rows around caudal peduncle 16. Four to six minute contact organs on each scale of ventral portion of flanks and opercular region in males. Row of contact organs on three uppermost pectoral-fin rays, and sometimes on distal portion of anteriormost anal-fin rays in males. No contact organ on dorsal and caudal fins.

Cephalic neuromasts: supraorbital 17-18, parietal 2-3, anterior rostral 1, posterior rostral 1, infraorbital 3 + 25-28, preorbital 3, otic 2-3, post-otic 4, supratemporal 1, median opercular 1, ventral opercular 2-3, preopercular 24-28, mandibular 11-15, lateral mandibular 5-6.

Basihyal nearly triangular, width about 50-55 % of length; basihyal cartilage long, about 60-70 % of total basihyal length, with pronounced lateral projection. Six branchiostegal rays. Eight to twelve teeth on second pharyngobranchial. Gill-rakers on first branchial arch 3-4 + 11-12. Sometimes two or one minute dermosphenotic ossifications. Ventral process of posttemporal long. Total vertebrae 29-32.

Coloration

Males: sides of body dark greenish to bluish gray, sometimes with intense light blue iridescence; 7-12 vertical rows of light blue dots. Sides of head dark greenish gray to bright blue on opercular and infraorbital regions; approximately triangular, narrow black infraorbital bar, ventral tip directed ventroposteriorly; subtriangular black supraorbital bar, not extending to parietal series of neuromasts. Iris dark brownish yellow, with black bar through center of eye. Dorsal fin dark bluish gray,, with one or two rows of white dots on basal half. Anal fin dark bluish gray, often with light blue iridescence; transverse row of white dots on basal portion and black distal line. Caudal fin dark bluish gray, with white dots on basal half; marginal region hyaline. Pelvic fins dark bluish gray with black tip. Pectoral fins hyaline, with dark bluish gray ventral margin.

Females: sides of body light yellowish brown, with vertically elongate dark gray spots, often vertically arranged, sometimes forming bars; rarely one or two black spots on anterocentral portion of flank; 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

Lower río de La Plata basin and adjacent coastal plains to south, Argentina (Fig. 11).

Remarks

Cynolebias gibberosus has been considered a synonym of C. bellottii , which has been confirmed after examination of the syntypes. Vaz-Ferreira and Sierra (1973) claimed that the type specimens of C. gibberosus had had their morphology pathologically altered, with anomalies in the vertebral column resulting in exposed neural spines. In fact, the original description was based on two specimens, which show a high degree of contraction of the fleshy parts due to desiccation. Consequently, the jaw bones and first neural spines are externally exposed, and the body is twisted, making it difficult to take precise measurements. These exposed neural spines were described by Berg (1897) as osseous tubercles, which were considered to constitute the main diagnostic character of C. gibberosus . The material used in the original description is MACN 5172, a male about 70 mm SL, is herein designated as lectotype, and MACN 5177, a female about 50 mm SL, is designated as paralectotype.