Compiled from Roth & Sadeghian's checklist, largely making use of their county listings. I've omitted species of Carychium in an attempt to be comprehensive with a single taxon (Stylommatophora), since I believe Roth and Sadeghian comes close to this for that group, and I've also omitted species they listed as extinct and subspecies that could not be found in iNat's external name providers. I have maintained all taxa at the species rank with the exception of species that do not seem to be formally described (Ariolimax stramineus and Nearctula dalliana), and I have tried to maintain their listings of introduced species. I have also tried to note Channel Island distributions in the descriptions, as well as introduced species, but I have refrained from marking any species as endemic, even though many probably are, because it's unclear from the text whether omission of out-of- state ranges indicates endemism in California. I've also chosen to mark these lists as comprehensive, even though the authors list numerous undescribed species and make a note in the introduction about numerous other species awaiting description. That said, I consider this publication to be comprehensive given the current state of taxonomy, as it seems to me the state has been relatively well-sampled for snails, and comprehensiveness is always a moving target anyway. All errors are my own, and if you find any, please let me know.
Santa Catalina Island
Also on Santa Cruz and Santa Catalina Islands
Also on Santa Cruz Island
San Clemente Island
Santa Catalina Island
Santa Catalina Island
San Clemente Island
San Clemente Island
Santa Catalina Island, but also on the mainland (?)
Also present on Santa Catalina, San Nicolas, and San Clemente Islands.
Also on Santa Catalina Island
Also on Santa Cruz, San Nicolas, and Santa Catalina Islands
On Santa Cruz Island
Restricted to West Anacapa, Santa Cruz, and Santa Catalina Islands
Also on Santa Cruz and Santa Catalina Islands
Also on Santa Catalina Island
Also on Santa Catalina Island
Also on Santa Cruz, Anacapa, and Santa Catalina Islands
Santa Catalina Island
Also on Isla Guadalupe in Mexico
Also on San Nicolas Island
Restricted to Santa Barbara, Santa Catalina, and San Clemente Islands in CA, also present on Isla Guadalupe in Mexico