Abstract
The new species Opiona graeningi is described from caves in the Marble Mountain Wilderness Area, Klamath National Forest, Siskiyou Co., California, as the first troglomorphic species of Opiona, the first troglobiont from the globally important KlamathSiskiyou ecoregion, and possibly the first troglobiotic caseyid. Notes are provided on the composition of the genus Opiona and on the interpretation of the gonopods. Opiona, with 13 described species, may not be monophyletic.
NSTL