Hesperoleucus symmetricus symmetricus ( Baird & Girard, 1854 )

Baumsteiger, Jason & Moyle, Peter B., 2019, A reappraisal of the California Roach / Hitch (Cypriniformes, Cyprinidae, Hesperoleucus / Lavinia) species complex, Zootaxa 4543 (2), pp. 221-240 : 228-229

Hesperoleucus symmetricus symmetricus ( Baird & Girard, 1854)

Central California Roach

This subspecies is consistent with the descriptions and distribution of the species itself, minus the Red Hills region. According to Baumsteiger et al. (2017), population structure is available within the subspecies, but only one lineage (see below) stood out in the genomic analyses and therefore would rise to the level of a DPS by our estimation. However, the presence of population structure and morphological differences ( Brown et al. 1992) within the subspecies indicates isolation/adaptation among locations that, if fully investigated, may warrant additional DPS designations. We would argue this should be investigated on a case-by-case basis to evaluate the level of isolation and potential threat to each population so as to not overuse the DPS designation within the U.S. Endangered Species Act.

Kaweah Roach. The current population of Kaweah Roach is highly isolated in the Kaweah River system, at the southern end of the CA Roach range. Some morphometric characters are distinctive in Kaweah Roach, including a high prevalence of chisel-lip ( Brown et al. 1992). Although found to be genetically ( Aguilar & Jones 2009) and genomically distinct ( Baumsteiger et al. 2017), these determinations were only discovered once analyses were restricted to CA Roach samples. Therefore, we believe Kaweah Roach is a unique evolutionary lineage within CA Roach, representing a distinct population segment (DPS) that should be managed accordingly.

Description. Kaweah Roach are largely similar to the description for CA Roach, with slightly different morphometric and meristic mean counts reported ( Brown et al. 1992). This includes a higher prevalence of chisellip, similar to Red Hills Roach.

Distribution. This distinct population segment appears to be isolated in the Kaweah River above Kaweah Reservoir. Historically it may have occurred on the Valley floor, in places such as Tulare Lake or in the lower reaches of nearby river systems such as the Kings River. Such access is now denied by dams, diversions, and altered habitats.

Status. This DPS is reasonably safe, at least in the short run (50 years). The upper half of the range within the Kaweah River is bounded by Kings Canyon National Park and as such receives special protection. The lower half, which flows mostly through private lands before ending up in Kaweah Reservoir, is less secure. Individuals here may be at risk from upstream movement of invasive species such as Largemouth Bass, Micropterus salmoides , a factor which will intensify with climate change and warmer temperatures.