The radiation of alopiine clausiliids in the Sicilian Channel (Central Mediterranean): phylogeny, patterns of morphological diversification and implications for taxonomy and conservation ofMuticariaandLampedusa
Authors: Fiorentino V. , Salomone N. , Schembri P.J. , Manganelli G. , Giusti F. 
Published: October 2017

The phylogeny, biogeography and taxonomy of the alopiine clausiliids of the Sicilian Channel, belonging to the generaLampedusaandMuticaria, were investigated using morphological (shell characters and anatomy of the reproductive system) and genetic (sequencing of a fragment of the mitochondrial large ribosomal subunit 16S rRNA, and the nuclear internal transcriber spacer 1, ITS-1 rRNA) data. Classically, the genusLampedusaincludes three species:L. imitatrixandL. melitensisoccurring in circumscribed localities in western Malta and on the islet of Filfla, andL. lopadusaeon Lampedusa and Lampione. The genusMuticariaincludes two species in southeastern Sicily (M. siracusanaandM. neuteboomi) and one in the Maltese islands (M. macrostoma), which is usually subdivided into four entities based on shell characters (macrostomaon Gozo, Comino, Cominotto and central-eastern Malta;mamoticain southeastern Gozo;oscitanson Gozo and central-western Malta;scalarisin northwestern Malta). These have sometimes been considered as subspecies and sometimes as mere morphs.

TheLampedusaof Lampedusa and Lampione form a well distinct clade from those of the Maltese Islands. The population of Lampione islet is a genetically distinct geographic form that deserves formal taxonomic recognition (asL. nodulosaorL. l. nodulosa). TheLampedusaof Malta are morphologically distinct evolutionary lineages with high levels of genetic divergence and are confirmed as distinct species (L. imitatrixandL. melitensis).

TheMuticariaconstitute a clearly different monophyletic clade divided into three geographical lineages corresponding to the Sicilian, Maltese and Gozitan populations. The SicilianMuticariaform two morphologically and genetically distinguishable subclades that may either be considered subspecies of a polytypic species, or two distinct species. The relationships of Maltese and GozitanMuticariaare complex. Two of the three Maltese morphotypes resulted monophyletic (oscitansandscalaris) while the other was separated in two lineages (macrostoma); however this picture may be biased as only few samples ofmacrostomawere available to study. The Gozitan morphotypes (macrostoma,mamoticaandoscitans) where resolved as polyphyletic but with clear molecular evidence of mixing in some cases, indicating possible relatively recent differentiation of the GozitanMuticariaor repetitive secondary contacts between different morphotypes. Definitive taxonomic conclusions from these results are premature. MalteseMuticariacould be subdivided into three taxa according to morphological and molecular data (M. macrostomaorM. m. macrostoma,M. oscitansorM. m. oscitans and M. scalarisorM. m scalaris). GozitanMuticariacould be considered a distinct polytypic species (for which the oldest available name isMuticaria mamotica)subdivided into subspecies showing a morphological range frommacrostoma-like tomamotica-like andoscitanslike.

Only the two Maltese species ofLampedusaare legally protected (by the European Union’s ‘Habitats Directive’ and Maltese national legislation). The present study has shown that the alopiine clausiliids of the Sicilian Channel constitute a number of genetically and/or morphologically distinct populations that represent important pools of genetic diversity, with, in some cases, a very circumscribed distribution. As such, these populations deserve legal protection and management. It is argued that without formal taxonomic designation, it would be difficult to extend international legal protection to some of the more threatened of these populations.