Globose-shelled to depressed-helicoid terrestrial snails of the subgenus Helminthoglypta (Charodotes) occur from the vicinity of Morro Bay to the City of San Luis Obispo in San Luis Obispo County, central California, USA. Populations with intensely papillose shells largely or entirely lacking incised spiral sculpture, originally described as "Helix var. morroensis," have been regarded as either a subspecies of Helminthoglypta walkeriana (Hemphill, 1911) or an infrasubspecific variation without taxonomic significance. Shell form variation is distributed as one would expect if the two major aggregations of individuals were reproductively isolated, biological species, H. walkeriana and H. morroensis (Hemphill, 1911). Differing penial morphology is also consistent with reproductive isolation. The two species appear to be allopatric.
Interpretations of the SJ-6 seismic reflection/refraction profile, South Central California, USA