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Plant trade and exchange for horticulture, recreation or research play a significant role in the dispersal of molluscs. Alien slugs and snails accidentally introduced into Europe have established rich communities in several countries, but although these introductions could have ecological and economic implications, mollusc xenodiversity in Italian botanical gardens, plant nurseries, and greenhouses has never been investigated. Facilities throughout the country were therefore visited between 2017 and 2023. Here the list of the achatinoidean species so far recorded from Italian greenhouses is provided, giving a short description of their diagnostic characters. The greenhouses of Trento and Padua host interesting assemblages of achatinoideans: the results of this study include the first reports of four achatinids, namely Allopeasclavulinum , Opeashannense , Paropeasachatinaceum and Subulinaoctona from Italy and the first record of Geostilbiaaperta from Europe. Reproductive anatomy of all species except Geostilbiaaperta is illustrated in detail, integrating anatomical knowledge of this group of tiny molluscs, some of which are known mainly from their shell characters. The systematics of all the species is discussed, highlighting topics for future research (e.g., status of Allopeasmauritianum , real identity of Helixhannense , anatomy of Opeashannense , species-level taxonomy of Subulina , systematic relationships and species-level taxonomy of Geostilbia )., Competing Interests: The authors have declared that no competing interests exist., (Giuseppe Manganelli, Andrea Benocci, Debora Barbato, Folco Giusti.)

Features of shell and genitalia as well as nucleotide sequences of selected mitochondrial and nuclear genes of specimens of Monachacantiana from ten northern French and two Dutch populations were compared with the same features of British and Italian populations. They were found to be very similar to populations previously identified as belonging to the CAN-1 lineage of M.cantiana . This confirms previous suggestions that M.cantiana was introduced to western Europe (England, France and the Netherlands) in historical times., Competing Interests: The authors have declared that no competing interests exist., (Joanna R. Pieńkowska, Giuseppe Manganelli, Małgorzata Proćków, Debora Barbato, Katarzyna Sosnowska, Folco Giusti, Andrzej Lesicki.)

Specimens obtained from ten populations of a Monacha species from the central Apennines were compared with six molecular lineages of Monacha cantiana s. l. (CAN-1, CAN-2, CAN-3, CAN-4, CAN-5, CAN-6) and two other Monacha species ( M. cartusiana and M. parumcincta ), treated as outgroup, by molecular (nucleotide sequences of two mitochondrial COI and 16S rDNA as well as two nuclear ITS2 and H3 gene fragments) and morphological (shell and genital anatomy) analysis. The results strongly suggest that these populations represent a separate species for which two names are available: the older Helix pantanellii De Stefani, 1879 and the junior M. ruffoi Giusti, 1973. The nucleotide sequences created well separated clades on each phylogenetic tree. Genital anatomy included several distinctive features concerning vaginal appendix, penis, penial papilla and flagellum; instead, shell characters only enabled them to be distinguished from M. cartusiana and M. parumcincta . Remarkably, populations of M. pantanellii show high morphological variability. Shell variability mainly concerns size, some populations having very small dimensions. Genital variability shows a more intricate pattern of all anatomical parts, being higher as regards the vagina and vaginal appendix. Despite this morphological variability, the K2P distance range of COI sequences between populations is narrow (0.2-4.5%), if we consider all but three of the 53 sequences obtained. This research confirmed that the species of Monacha and their molecularly distinguished lineages can only occasionally be recognised morphologically and that they have significant inter- and intra-population variability. The possibility of using an overall approach, including shell, genital and molecular evidence, was taken in order to establish a reliable taxonomic setting., (Joanna R. Pieńkowska, Giuseppe Manganelli, Folco Giusti, Debora Barbato, Ewa Kosicka, Alessandro Hallgass, Andrzej Lesicki.)

Two new lineages CAN-5 and CAN-6 were recognised in four populations of Monachacantiana (Montagu, 1803) s.l. from the Italian Apuan Alps by joint molecular and morphological analysis. They are different from other M.cantiana lineages known from English, Italian, Austrian and French populations, i.e. CAN-1, CAN-2, CAN-3 and CAN-4, as well as from the other Italian Monacha species used for comparisons ( M.parumcincta and M.cartusiana ). Although a definite taxonomic and nomenclatural setting seems to be premature, we suggest that the name or names for these new lineages as one or two species should be found among 19 th century names ( Helixsobara Mabille, 1881, H.ardesa Mabille, 1881, H.apuanica Mabille, 1881, H.carfaniensis De Stefani, 1883 and H.spallanzanii De Stefani, 1884).

Molecular analysis of nucleotide sequences of mitochondrial cytochrome oxidase subunit 1 (COI) and 16S ribosomal DNA (16SrDNA) as well as nuclear histone 3 (H3) and internal transcribed spacer 2 of rDNA (ITS2) gene fragments together with morphological analysis of shell and genitalia features showed that English, French and Italian populations usually assigned to Monacha cantiana consist of four distinct lineages (CAN-1, CAN-2, CAN-3, CAN-4). One of these lineages (CAN-1) included most of the UK (five sites) and Italian (five sites) populations examined. Three other lineages represented populations from two sites in northern Italy (CAN-2), three sites in northern Italy and Austria (CAN-3), and two sites in south-eastern France (CAN-4). The taxonomic and nomenclatural setting is only currently available for lineages CAN-1 and CAN-4; a definitive frame for the other two requires much more research. The lineage CAN-1 corresponds to the true M. cantiana (Montagu, 1803) because it is the only one that includes topotypical English populations. The relationships and genetic distances support the hypothesis of the Italian origin of this lineage which was probably introduced to England by the Romans. The lineage CAN-4 is attributed to M. cemenelea (Risso, 1826), for which a neotype has been designated and deposited. Its diagnostic sequences of COI, 16SrDNA, H3 and ITS2 genes have also been deposited in GenBank. Molecular and morphological (shell and genitalia) features showed that M. parumcincta (Rossmässler, 1834) is a distinct taxon from the M. cantiana lineages.