Ariolimax buttoni

The species buttoni was first described by Pilsbry and Vanatta (1896) from a large series of aphallic ariolimacines from Oakland, California as a new genus. Subsequently this taxon was synonymized to Ariolimax (Ariolimax) columbianus (Gould in Binney, 1951) (Waste, 1940; Mead, 1943; Pilsbry, 1948). Recent molecular evidence suggests that A. columbianus, as defined by Mead (1943) and Pilsbry (1948), is not monophyletic but rather that populations of Ariolimax north of Mendocino Co., California (the true A. columbianus, since the species was described from specimens collected near the Columbia River) are evolutionarily distinct from the more southern populations (Leonard et al., 2005; Pearse et al., 2005). The name Ariolimax buttoni (Pilsbry and Vanatta, 1896) has been revived to designate the southern clades formerly included in A. columbianus (see Leonard et al., 2007).

Recently separated taxonomically from Ariolimax columbianus, this species occurs from Tuolomne Co., Monterey Co., the eastern shore of San Francisco bay (including Alameda, Sacramento, Mendocino, Marin, and San Francisco Co.) and the City of San Francisco; and is expected in Shasta Co.

Recently separated taxonomically from Ariolimax columbianus, this species occurs from Tuolomne Co., Monterey Co., the eastern shore of San Francisco bay (including Alameda, Sacramento, Mendocino, Marin, and San Francisco Co.) and the City of San Francisco (Leonard et al., 2007). It is also expected to occur in Shasta Co. (Roth and Sadeghian, 2006).