Alien molluscan species established along the Italian shores: an update, with discussions on some Mediterranean “alien species” categories

Abstract

The state of knowledge of the alien marine Mollusca in Italy is reviewed and updated. Littorina saxatilis (Olivi, 1792), Polycera hedgpethi Er. Marcus, 1964 and Haminoea japonica Pilsbry, 1895are here considered as established on the basis of published and unpublished data, and recent records of the latter considerably expand its known Mediterranean range to the Tyrrhenian Sea. COI sequences obtained indicate that a comprehensive survey of additional European localities is needed to elucidate the dispersal pathways of Haminoea japonica.Recent records and interpretation of several molluscan taxa as alien are discussed both in light of new Mediterranean (published and unpublished) records and of four categories previously excluded from alien species lists. Within this framework, ten taxa are no longer considered as alien species, or their records from Italy are refuted. Furthermore, Trochocochlea castriotae Bellini, 1903 is considered a new synonym for Gibbula albida (Gmelin, 1791). Data provided here leave unchanged as 35 the number of alien molluscan taxa recorded from Italy as well as the percentage of the most plausible vectors of introduction, but raise to 22 the number of established species along the Italian shores during the 2005–2010 period, and backdate to 1792 the first introduction of an alien molluscan species (Littorina saxatilis) to the Italian shores.

Biogeographical homogeneity in the eastern Mediterranean Sea - I: the opisthobranchs (Mollusca: Gastropoda) from Lebanon

“…200 alien molluscan species (Zenetos et al, 2012). However, only some of these are now considered well established (Zenetos et al, 2010;Crocetta et al, 2013), with multiple records from all over the Mediterranean Sea and/or massive presence in some areas, whilst others (e.g. Halgerda willeyi, Dendrodoris fumata, Cuthona perca, Caloria indica, Baeolidia moebii) were recorded in the Mediterranean Sea by only one or few very isolated specimens (Barash & Danin, 1986;Perrone, 1995;Gat, 1993;Turk, 2000;Turk & Furlan, 2011) and might be considered as ephemeral entries, especially when their records date back several decades.…”

Anadara kagoshimensis (Mollusca: Bivalvia: Arcidae) in Adriatic Sea: morphological analysis, molecular taxonomy, spatial distribution, and prediction

“…Finally, Huber (2010) suggested that the Mediterranean alien species matched A. kagoshimensis from Japan. Subsequently, some scientists have begun to identify these ark clams as A. kagoshimensis (Zenetos et al, 2010;Crocetta, 2011Crocetta, , 2012Lipej et al, 2012;Crocetta et al, 2013;Despalatović et al, 2013;Grati et al, 2013), whereas others still consider the species as A. inaequivalvis or S. inaequivalvis (Andreani et al, 2011;Foschi et al, 2011;Occhipinti-Ambrogi et al, 2011;Mistri & Munari, 2013;Huntley & Scarponi, 2015), although it is unclear whether they have failed to accept or have merely ignored the taxonomic change.…”

The evolution of the molluscan biota of Sabaudia Lake: a matter of human history

“…A wider study for the occurrence of Crassostrea oysters in the CNP marine area revealed its presence in the Circeo harbour (Latium, Tyrrhenian Sea) too, where it can be commonly found attached to the dock walls (Macali, unpublished data). Recent records of Haminoea japonica from Sabaudia Lake have considerably expanded its known Mediterranean range to the Tyrrhenian Sea (Crocetta et al 2013) and, according to our field observations, this species has completely replaced populations of other native Haminoea species. This finding is paralleled by a similar observation by Hanson et al (2013), who reported the complete replacement of the once common Haminoea vesicula (Gould, 1855) in Boundary Bay (North America).…”

“…Finally, four individuals of the slipper limpet Crepidula fornicata were found attached to Crassostrea: this is the second record of this species in the CNP wetlands after its first record from Caprolace Lake (Bini 1983b). However, no established populations have been found in the area, so the species is conservatively considered as casual (Crocetta et al 2013): these specimens may be the result of periodical re-introduction of Crassostrea oysters in the lake, presumably from the Atlantic shores. The same can be said for Rapana venosa: despite its recent collection in 2005 (Crocetta and Soppelsa 2006), the absence of further records suggests that its ephemeral introduction may be connected with mussel imports from the northern Adriatic Sea.…”

“…-Summary of the commonest species observed in both clusters (MCSBC), the most frequently observed species exclusive to the Channel Cluster (MFSCC) and exclusive species of the Inner Cluster (ESIC), listed in systematic order within each cluster. Bold: alien species in the Italian territorial seawaters (Crocetta 2012, Crocetta et al 2013 (Linnaeus, 1758) Callistoctopus macropus (Risso, 1826) Venerupis philippinarum (Adams A. and Reeve, 1850) Octopus vulgaris Cuvier, 1797…”