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, <i>Siphateles</i> spp., are found widely across the Great Basin and in some adjacent regions. Nearly all diversity of <i>Siphateles</i> has been consolidated under the name <i>S. bicolor</i> 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 <i>S. bicolor</i> 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 <i>S. bicolor</i> sensu lato using mitochondrial data and then conducting phylogenetic analyses of genome-wide SNP data. <i>Siphateles bicolor</i> is better characterized by seven species, all with existing names, which here are considered to be valid <i>Siphateles</i> species. Furthermore, the separation of Alvord Basin <i>Siphateles</i> from other <i>Siphateles</i> is apparent as a deeply divergent lineage. As a result, we propose <i>Epizon</i> Campbell & Finger, <b>gen. nov.</b> to contain these fishes. The Fish Lake Valley Tui Chub is found to be the earliest-branching lineage of <i>S. obesus</i> in our SNP data set and are highly differentiated from other <i>S. obesus</i>. 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 <i>S. obesus</i> is appropriate.