Distribution and Conservation Status ofOmus submetallicusG. Horn and Its Confusion withOmus californicus leconteiG. Horn (Coleoptera: Carabidae)

Abstract

We conducted studies to determine the distribution, abundance, and conservation status of Omus submetallicus G. Horn. From pitfall traps and visual searches, we found 286 O. submetallicus adults at six sites in far western Fresno County, California where larval burrows were abundant and widespread. The same survey methods produced 975 Omus californicus lecontei G. Horn, mostly from seven sites in San Benito County, but others from two sites, one within 300 m of one of the O. submetallicus sites. Contrary to previous reports, we conclude that O. submetallicus does not occur in Monterey County (including Priest Valley) or in Kings County, but ranges east of the designated Warthan Canyon type locality where the habitat is generally drier and less densely vegetated than most of the rest of the canyon. Omus submetallicus is primarily associated with blue oak woodland and bull (digger) pine, but not with poison oak as previously reported. We predict that the actual range of O. submetallicus extends several miles north and south of the sites where we found it along Hwy. 198 because similar habitat is present in various small canyons there. This area is mostly private property, roadless, and accessible only on foot, so thorough surveys are difficult. All populations were on private lands used for low intensity cattle grazing which does not seem to pose a significant risk to the species. Because this area is unlikely to be developed in the near future, the species does not seem to be in danger of extinction at this time, despite its extremely limited geographic range.