Foskett spring speckled dace

Brian Sidlauskas, Kendra Hoekzema

Latin name: Rhinichthys osculus ssp.

The Foskett Speckled Dace is a minnow native to a single isolated spring in Oregon’s Warner Valley, listed as federally threatened in 1985 due to its small population size and potential threats to its limited native range from irrigation and livestock. Kendra Hoekzema and Brian Sidlauskas studied the genetic relationships of Foskett Dace to Speckled Dace from streams and springs elsewhere in Oregon’s Great Basin, and confirmed their status as distinct population of a more widely distributed species. These genetic results form part of the evidence reviewed by the US Fish and Wildlife Service in their recent proposal to delist the Foskett Dace.

Master's student Kendra Hoekzema combined genetics and morphology to investigate the biogeography and taxonomic status of speckled daces (Rhinichthys osculus) throughout Oregon's Great Basin. She found that Foskett Spring dace, which are federally listed as a threatened subspecies, actually represent a morphologically distinctive population, but that three cryptic species of daces in this region deserve recognition.

Did you know? While Foskett Spring Speckled Dace merits recognition as only a distinct population, not a species or subspecies, this investigation revealed the presence of deep genetic divisions elsewhere in the state that suggest the presence of additional undescribed species within the present concept of Speckled Dace.


Policy document:  Delisting proposal