Occurrence in mexico of two european invasive slug species: Arion vulgaris moquin-tandon, 1855 and arion intermedius (Norman, 1852)

Knowledge of invasive terrestrial gastropods species in Mexico, and their potential impacts, is practically unknown. We document in this study, the occurrence of the large invasive slug Arion vulgaris Moquin-Tandon, 1855 for the first time in Mexico and only the third time in North America. In addition, we also report Arion (Kobeltia) intermedius Normand, 1852 from seven localities demonstrating that the species is already well established in Mexico. To identify both species, a Maximum-Likelihood phylogenetic analysis was performed using partial sequences, alone or concatenated, of nicotinamide adenine dinucleotide dehydrogenase 1 (ND1) and cytochrome C oxidase 1 (COI) genes. In addition, we used the morphological characters reported in other studies of these species to confirm their taxonomic identity. The phylogenetic analysis performed with the concatenated ND1 and COI genes, showed that the Mexican sequences of A. vulgaris were grouped with the corresponding sequences of this species from Canada and European countries. In addition, attributes such as the shape and position of the ligula were useful to confirm the taxonomic identity of this species. On the other hand, the phylogenetic analysis using ND1 sequences alone clustered Mexican specimens of A. intermedius with sequences of this species from Spain and UK. Characters such as the body color pattern, prickles on the dorsum, as well as characters of the reproductive system of A. (K.) intermedius corroborated the taxonomic identity of Mexican specimens of this species.