The Coyote Mountains' Desert Snail (Sonorelix harperi carrizoensis), a Lazarus Species with the First Documentation of Live Individuals

Abstract

The Coyote Mountain desert snail (Sonorelix harperi carrizoensis) was described in 1937 from 30 dry shells collected the previous year. We reviewed the literature and museum records and found two additional shell collections for this subspecies from the type locality one from 1958, and one from an adjacent mountain range in 1938. There is no evidence previously of any live snails being collected from the Coyote Mountains, Imperial County, California. All shell collections of S. harperi carrizoensis have the same locality data as the type series, which is Painted Gorge, Coyote Mountains except for one recorded collection of shells from the Vallecito Mountains from 1938. Using geological maps and other data sources, a potential mesic habitat was identified in the Coyote Mountains. During recent field work for salamanders at this location we detected two live specimens of S. harperi carrizoensis approximately 2 km north of its type location. This new data confirms this subspecies is still extant and has occurred at least at two sites historically in these mountains. Despite the presence of mesic habitats (i.e., mosses, liverworts and ferns) at the type locality, we found no evidence of S. harperi carrizoensis or salamanders. California has a highly diverse terrestrial snail and slug fauna of over 360 taxa, with a high number of locally endemic taxa (Roth and Sadeghian 2003). This fauna is dominated by the family Helminthoglyptidae, with several endemic desert genera including the genus Sonorelix (Roth and Sadeghian 2003; Goodward et al. 2017). Imperial County has the most depauperate snail fauna of any county in California with only three native snails known from the desert mountains, including two subspecies of Sonorelix harperi and one subspecies of Eremarionta rowelli (Roth and Sadeghian 2003). Two of these subspecies (Sonorelix harperi carrizoensis and Eremarionta rowelli chocolata) are endemic to Imperial County and are both poorly known in the literature or museum collections, with no evidence of recent collections for either of these endemic subspecies (Roth, pers comm.; SBNHM and SDSNH search 1 May 2020). Both subspecies were described in the 1930s from remote mountain ranges by George Willett who focused on resolving the taxonomy of these desert snails (1935, 1937), neither of these endemics have received any critical attention since these descriptions. Similar to these snails, salamanders are also poorly known from Imperial County, with only two specimens of Southern California slender salamanders (Batrachoseps major) having been collected previously, each from a different mountain range [SDSNH 16316 (1933)