From the mud to the tree: phylogeny of Austrolebias killifishes, new generic structure and description of a new species (Cyprinodontiformes: Rivulidae) Author Alonso, Felipe Instituto de Bio y Geociencias del NOA (IBIGEO), National Scientific and Technical Research Council (CONICET) - UNSa, Av. 9 de Julio 14, A 4405 BBA Rosario de Lerma, Salta, Argentina & Killifish Foundation, La Plata, Buenos Aires Province, Argentina Author Terán, Guillermo Enrique Killifish Foundation, La Plata, Buenos Aires Province, Argentina & Fundación Miguel Lillo - Unidad Ejecutora Lillo (CONICET), San Miguel de Tucumán, Tucumán, Tucuman Province, Argentina Author Alanís, Wilson Sebastián Serra Killifish Foundation, La Plata, Buenos Aires Province, Argentina & Sección Ictiología, Departamento de Zoología, Museo Nacional de Historia Natural, Montevideo, Uruguay & Centro Universitario Regional del Este (CURE) Sede Rocha, Rocha, Uruguay Author Calviño, Pablo Killifish Foundation, La Plata, Buenos Aires Province, Argentina Author Montes, Martin Miguel Killifish Foundation, La Plata, Buenos Aires Province, Argentina & Centro de Estudios Parasitológicos y de Vectores - [CCT-CONICET - La Plata] Centro Científico Tecnológico Conicet, La Plata - [Conicet] Consejo Nacional De Investigaciones Científicas y Técnicas, La Plata, Buenos Aires Province, Argentina Author García, Ignacio Daniel Killifish Foundation, La Plata, Buenos Aires Province, Argentina & Instituto de Limnología ‘ Dr. Raúl Ringuelet’ (ILPLA) - UNLP-CONICET, La Plata, Buenos Aires Province, Argentina Author Barneche, Jorge Adrián Killifish Foundation, La Plata, Buenos Aires Province, Argentina & Centro de Estudios Parasitológicos y de Vectores - [CCT-CONICET - La Plata] Centro Científico Tecnológico Conicet, La Plata - [Conicet] Consejo Nacional De Investigaciones Científicas y Técnicas, La Plata, Buenos Aires Province, Argentina Author Almirón, Adriana Universidad Nacional de La Plata, Facultad de Ciencias Naturales y Museo, División Zoología Vertebrados, La Plata, Buenos Aires Province, Argentina Author Ciotek, Liliana Administración de Parques Nacionales, Parque Nacional Campos del Tuyú (7103), General Lavalle, Buenos Aires Province, Argentina Author Giorgis, Pablo Administración de Parques Nacionales, Parque Nacional Campos del Tuyú (7103), General Lavalle, Buenos Aires Province, Argentina Author Cascioưa, Jorge Universidad Nacional de La Plata, Facultad de Ciencias Naturales y Museo, División Zoología Vertebrados, La Plata, Buenos Aires Province, Argentina text Zoological Journal of the Linnean Society 2023 2023-07-10 199 1 280 309 http://dx.doi.org/10.1093/zoolinnean/zlad032 journal article 266147 10.1093/zoolinnean/zlad032 684543f4-855c-492a-b163-a157473a187c 0024-4082 8326346 E1210342-9DBD-4D89-ABF5-1925792D0E14C 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 .