Leucos Heckel, 1843

Bianco, Pier Giorgio & Ketmaier, Valerio, 2014, A revision of the Rutilus complex from Mediterranean Europe with description of a new genus, Sarmarutilus, and a new species, Rutilus stoumboudae (Teleostei: Cyprinidae), Zootaxa 3841 (3), pp. 379-402 : 382

Genus Leucos Heckel, 1843

Type species: Squalius aula Bonaparte, 1841 : Fauna It., fasc. XXX, Tav. 116, fig. 3: type locality; Padua Province; north-eastern Italy.

Leucos cisalpinus Heckel, 1843: 1081 (Lake Garda) was the subsequent type species designation by Jordan & Gilbert (1883). But it was a nomen nudum. Type species by present designation: Squalius aula Bonaparte, 1841 : type locality; Italy, Padua Province, north-eastern Italy. It is the only species from Lake Garda, common in every lake of northern Italy, which corresponds with the short description below of the genus. A short diagnosis (translated from Latin) of this genus was given by Heckel, (1843:1081): pharyngeal teeth, 5-5; mouth small; lips smooth; barbels absent; dorsal and anal fins short; origin of D at level of insertion of pelvic fins. Others species placed by Heckel (1843) in this genus: Leucos rubella Heckel, 1843 (nomen nudum); Leucos basak Heckel, 1843 ; Leucos (now placed in Delminichthys ) adspersus Heckel, 1843, Leuciscus selysii Selys-Longchamps, 1841 (junior synonym of Rutilus rutilus ); and Leuciscus rutiloides Selys-Longchamps, 1842 (junior synonym of R. rutilus ). The genus Leucos was used by several authors until it was synonymized with Rutilus ( Howes, 1981) .

Diagnosis. Distinguished from others genera of European cyprinids by a combination of the following characters: pharyngeal teeth 5-5 (rarely 4-5 or 5-4 or 6-5) hooked and slightly serrated. Mouth small, terminal or slightly upturned or downturned; origin of D nearly at same level of origin of P2; free margin of D and A concave or slight concave; caudal fin from moderately to deeply forked; peritoneal membranae from silvery to blackened by fused melanophores; body without longitudinal stripes (excepted Leucos aula ). GR short. Usually, 8–9 branched rays in the D and in the A; 8 branched rays in the P2; 12–14 circum-peduncular scales; absence of large pearl organ (nuptial tubercles) on head and central part of scales in reproductive males; small size, did not exceed 180 mm SL; mostly a still water species. Sequence variation of the entire mitochondrial cytochrome b gene shows a strictly relationship among five species, which separated from a Leuciscinae ancestor about 4-5 milion years ago, during the Lago Mare phase of the Mediterranean ( Bianco, 1990), probably following the same evolutionary trajectories of the genus Telestes , which occurs in the same geographic area ( Ketmaier et al., 2004).