Cypholebias Costa, 2008

Alonso, Felipe, Terán, Guillermo Enrique, Alanís, Wilson Sebastián Serra, Calviño, Pablo, Montes, Martin Miguel, García, Ignacio Daniel, Barneche, Jorge Adrián, Almirón, Adriana, Ciotek, Liliana, Giorgis, Pablo & Cascioưa, Jorge, 2023, From the mud to the tree: phylogeny of Austrolebias killifishes, new generic structure and description of a new species (Cyprinodontiformes: Rivulidae), Zoological Journal of the Linnean Society 199 (1), pp. 280-309 : 291-292

Genus Cypholebias Costa, 2008 stat. nov.

Cypholebias Costa, 2008 as a subgenus of Austrolebias .

Type species: Cynolebias robustus Günther, 1883 .

Diagnosis: Cypholebias can be distinguished from the remaining genera of the Austrolebias genus group by the following unique characters states: (1) irregular light bands on flanks; and (2) acute angle between the articular facet of the second pharyngobranchial with the distal condyle of second epibranchial.

The following characters are also useful to recognize this genus: (3) rounded caudal fin in males (paralleled in Argolebias paranaensis and Titanolebias , except T. cheradophilus ); (4) 26–30 caudal fin rays (paralleled in Ma. litzi, Ma. cyaneus, Ma. paucisquama and Austrolebias melanoorus ); (5) contact organs on the anal fin of males (paralleled in Titanolebias and Acantholebias ); (6) extension of the anterior portion of the entopterygoid in relationship to the autopalatine not overlapping (paralleled in Megalebias and Titanolebias ); and (7) pelvic bones overlapping (paralleled in Austrolebias ).

Differential diagnosis: The genus Cypholebias can be distinguished from all other genera of the Austrolebias genus group by having <40 scales in the longitudinal series (vs.> 40 scales in Titanolebias ); by the presence of scales in the preopercular region (vs. absent in Gymnolebias ); by the basal and medial region of pectoral fins being non-hyaline in adult males (vs. hyaline in Amatolebias , Austrolebias and Garcialebias ); by the presence of non-ossified contact organs on the anal fin of males (vs. contact organs absent in Matilebias , Argolebias , Cypholebias and Megalebias , and ossified contact organs in Acantholebias ).

Synapomorphies: Cypholebias was recovered as monophyletic and supported by seven morphological synapomorphies (see Supporting Information, Appendix S5): irregular light bands on flanks (22:1); rounded caudal fin in males (54:0); 26–30 caudal fin rays (59:1); contact organs on the anal fin of males (86:1); extension of the anterior portion of the entopterygoid in relationship to the autopalatine, not overlapping (107:1); acute angle between the articular facet of the second pharyngobranchial with the distal condyle of second epibranchial (145:1); and pelvic bones overlapping (190:1).

Included species: Cypholebias robustus (Günther, 1883) comb. nov. and Cypholebias cinereus (Amato, 1986) comb. nov.

Remarks: Cynolebias nonoiuliensis Taberner , Fernández-Santos & Castelli, 1974 is considered a junior synonym of Cynolebias robustus because it lacks diagnostic characters and no morphological differences are observed between specimens of Cypholebias robustus and those from the type locality of Cynolebias nonoiuliensis ( Calviño 2003, Calviño et al. 2016, this study).

Distribution: Basins to the east of the lower Uruguay River, basins associated with the Merín lagoon and basins associated with the Río de la Plata and the Atlantic Ocean of the Province of Buenos Aires in Argentina, Brazil and Uruguay.