Abstract
Morphological and genetic revision of Central Asian minnows previously named as “Phoxinus” discovered a major novel evolutionary lineage of leuciscid fishes. According to both mitochondrial and nuclear DNA markers, the novel lineage is sister to large-sized fishes known as Altai osmans, the genus Oreoleuciscus; the high mtDNA p-distance between these lineages (0.113 ± 0.006) further supports the genetic distinctiveness of the new lineage. A new genus of minnows, Tianshanophoxinus, gen. nov. (Leuciscidae: Pseudaspininae), is described from the endorheic basins of Central Asia. This genus includes at least three species: T. poljakowii (Kessler, 1879), comb. nov., T. kuldschiensis (Warpachowski, 1887), comb. nov., and T. issykkulensis (Berg, 1912), comb. nov., all formerly placed in Phoxinus Rafinesque, 1820. Detailed morphological analyses clearly distinguish the lineage of Tianshanophoxinus from related genera (Phoxinus, Rhynchocypris, and Oreoleuciscus) based on unique characteristics such as the reduced number of pored scales in the lateral line, lower counts of pelvic-fin rays and caudal vertebrae, and distinct morphometric proportions. Phylogenetic evidence supports the monophyly of the genus and its placement within the subfamily Pseudaspininae of the family Leuciscidae. The species exhibit restricted distributions across the Lake Balkhash, Alakol, Issyk-Kul and Chu River basins, reflecting the geological and hydrological history of the region.