We wish to survey for populations of slender salamanders (genus Batrachoseps) in Boyd Deep Canyon Desert Research Center. The desert slender salamander, Batrachoseps (major) aridus is one of only two salamander taxa that are restricted to desert ecosystems. This species was described from a single tributary to Deep Canyon in 1970. It was classified as federally endangered shortly thereafter, in 1973, and has been fully protected since then. Survey work across dozens of springs and other sites with surface water led to the discovery of one additional population. Since 1979, no new populations of this taxon have been discovered. Furthermore, both of these populations may be extirpated, as no living individuals have been observed at either site for 25+ years. In 2023 and 2024, an extensive set of atmospheric rivers passed through southern California, stimulating a extensive fieldwork for salamanders in the desert and leading to the discovery of new populations in Anza Borrego State Park as well as confirmation of populations in the vicinity of Palm Springs. These two lineages are both more closely related to B. m. aridus than they are to any other lineage within Batrachoseps, based on sequencing of a mitochondrial gene fragment. Furthermore, they appear equally distance from B. m. aridus. While each of these lineages shares some morphological features with B. m. aridus, they are also distinct from it, and from each other. The discovery of these lineages has also changed our understanding of the potential habitat used by salamanders in the desert, suggesting that rock structure is at least as important as the presence of surface moisture for the persistence of salamander populations. An open question is what these new populations represent: are they morphologically differentiated populations within B. major or B. (m.) aridus or are they one or more new species. Answering this question is also relevant to the taxonomic status of the desert slender salamander, which is recognized by some authors as a distinct species, B. aridus and by others as a subspecies of B. major. B. aridus is very distinctive morphologically, but it is nested within B. major in analyses of both allozymic and mitochondrial DNA diversity. Contact zones between differentiated lineages provide natural experiments that are relevant to determining taxonomic status. Deep Canyon is a perhaps the most likely place for a contact zone, given that it lies downstream of B. aridus in a similar ecological setting to the populations on the outskirts of Palm Springs.

Approved