Evolutionary relationships of Fish Lake Valley Tui Chub Siphateles obesus ssp. (Teleostei, Cypriniformes, Leuciscidae) and a new genus of leuciscid minnows from the Alvord Basin, western United States

The Tui Chubs, Siphateles spp., are found widely across the Great Basin and in some adjacent regions. Nearly all diversity of Siphateles has been consolidated under the name S. bicolor and there are numerous isolated populations of Tui Chubs of uncertain taxonomic standing and therefore unclear conservation priority. The Fish Lake Valley Tui Chub (FLVTC) has been recognized informally as S. bicolor ssp. 4 with a limited natural distribution in Fish Lake Valley in southwest Nevada.

Considering that a rigorous examination of the phylogenetic relationships of the FLVTC and other Tui Chubs has not been conducted, the FLVTC is placed in a taxonomic framework by first applying a species delimitation method to S. bicolor sensu lato using mitochondrial data and then conducting phylogenetic analyses of genome-wide SNP data. Siphateles bicolor is better characterized by seven species, all with existing names, which here are considered to be valid Siphateles species.

Furthermore, the separation of Alvord Basin Siphateles from other Siphateles is apparent as a deeply divergent lineage. As a result, we propose Epizon Campbell & Finger, gen. nov. to contain these fishes. The Fish Lake Valley Tui Chub is found to be the earliest-branching lineage of S. obesus in our SNP data set and are highly differentiated from other S. obesus.

These findings are concordant with geologic evidence that indicates that Fish Lake Valley became connected to the broader Lahontan Basin ~ 2 million years ago, with gene flow possible until ~ 0.5 million years ago. Based on the geographic distribution and magnitude of genetic divergence, we find the recognition of FLVTC as a subspecies of S. obesus is appropriate.