Will the real invasive snail please stand up? A phylogenetic reconsideration of Paralaoma servilis (Shuttleworth, 1852) (Gastropoda: Stylommatophora: Punctidae)

Abstract

We reconsider the biodiversity and biogeography of Paralaoma servilis—believed to be one of the most globally invasive exotic land snails—through integrative empirical revision. Phylogenies obtained from nDNA (ELAV, ddRAD genomics) and mtDNA (COI) demonstrate that the current classification is in error, with there being at least five distinct species within P. servilis s.l. The P. servilis group as interpreted here thus includes: P. servilis, inferred to be native to south-western Pacific Rim with an adventive distribution minimally spanning North America, Europe, and the Macaronesian islands of the eastern Atlantic Ocean; P. amblygona (Reinhardt, 1877), native to Honshu, Japan; P. borealis (Pilsbry and Y. Hirase, 1905), native to Hokkaido, Japan along the Pacific Rim to the SW North American mountains; P. caputspinulae (Reeve, 1852), native to New Zealand and Lord Howe Island; and P. morti (J.C. Cox, 1864), native to south-eastern Australia. Within P. servilis, invasiveness appears limited to a single clade that may have arisen along the California coast. The work presented here is a reminder that taxonomic concepts that have not been subjected to empirical vetting can generate poor biodiversity perspectives and non-optimal conservation strategies when native species are treated as exotics.