Amatolebias, Alonso & Terán & Alanís & Calviño & Montes & García & Barneche & Almirón & Ciotek & Giorgis & Cascioưa, 2023

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 : 286-288

Amatolebias gen. nov.

LSID urn:lsid:zoobank.org:act:29852779-F2ED-4AA7-AE2D-B21307A10AC6

Type species: Austrolebias wichi Alonso et al., 2018 .

Diagnosis: Amatolebias is distinguished from the remaining genera of the Austrolebias genus group by the following unique combination of characters in mature dominant males: (1) well-defined and regular vertical dark grey bars only on the anterior portion of the flank (anterior to the anal fin origin); (2) scales on flanks, above anal fin and below dorsal fin leaden bluish to greenish, without wide dark grey border; (3) anal fin with a black band at the distal margin; (4) thin most exterior border of scales on dorsal half portion of flank, below dorsal fin, light grey to brownish grey; and (5) lateral margins of basihyal cartilage laterally expanded.

Differential diagnosis: The genus Amatolebias can be distinguished from all other genera of the genus group Austrolebias 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 hyaline in adult males (vs. non-hyaline in Argolebias , Acantholebias , Megalebias , Acrolebias , Cypholebias and Matilebias ); by presenting a black band at the distal margin of the anal fin and posterior region of the flanks with white spots vertically aligned in adult males (vs. without black band and white markings in Garcialebias ); from Austrolebias by the urogenital papillae not attached to the anal fin and no contact organs on anal fin in males [vs. urogenital papillae attached in Austrolebias melanoorus Amato, 1986 , Austrolebias queguay Serra & Loureiro, 2018 , Austrolebias univentripinnis Costa & Cheffe, 2005 , Austrolebias bellottii Steindachner, 1881 and Austrolebias ephemerus Volcan & Severo-Neto, 2019 , and contact organs present on anal fin of Austrolebias vandenbergi and Austrolebias accorsii ].

Synapomorphies: Amatolebias is recovered as monophyletic, supported by eight molecular synapomorphies and the following six morphological synapomorphies (see Supporting Information, Appendix S5): centre of most scales on ventral half of flank, above anal fin, in dominant mature males (excluding bands, bars and iridescent lines) bluish to greenish leaden (1:7); wide border of most scales on ventral half of flank, above anal fin, in dominant mature males (not considering bands, bars and iridescent lines) absent (2:0); centre of most scales on dorsal half of flank, below dorsal fin, in mature dominant males (not considering bands, bars and iridescent lines) bluish to greenish leaden (6:7); thin outermost edge of scales on dorsal half of flank, below dorsal fin, in dominant mature males (not considering bands, bars and iridescent lines) light grey to brownish grey (10:1); flanks with regular, well-defined vertical dark grey bars (16:1); and dark grey bars only on anterior portion of flank (anterior to anal fin origin) (17:1).

Included species: Amatolebias wichi Alonso et al., 2018 comb. nov., Amatolebias varzeae Costa et al., 2004 comb. nov. and Amatolebias patriciae Huber, 1995 comb. nov.

Etymology: Genus dedicated to Luis H. Amato, for his important contribution to the knowledge of the Rivulidae diversity of Uruguay, Paraguay and Brazil (Rio Grande do Sul); composed of his last name and from the Greek lebias (small fish, a name commonly used to compose generic names of cyprinodontiform fishes).

Distribution: Chacoan region of the Paraguay River basin in Argentina and Paraguay and the upper Uruguay River basin in Brazil.