Phylogeny and species delimitation in Albinaria from western Crete (Gastropoda: Clausiliidae)

We studied the phylogenetic relationships and species delimitation of the Albinaria species from western Crete classified in the A. candida group based on sequences of 2050 loci generated by double-digest restriction site-associated DNA sequencing. It turned out that neither the A. candida group nor the A. cretensis group is monophyletic and that the anterior palatal folds that allegedly characterize the species of the A. candida group were convergently reduced several times. That these folds are not suitable for diagnosing species groups became especially clear in the populations from Gramvousa Peninsula and adjacent areas, in which the development of the anterior palatal folds is variable. Previously populations with anterior palatal folds were classified as A. loosjesi, a species of the A. candida group, whereas populations without anterior palatal folds were classified as A. tenuicostata, a species of the A. cretensis group. Our analyses showed that they belong to a single species, A. grabusana (= A. loosjesi), which is not related to A. tenuicostata, but to A. xanthostoma from the neighbouring Rodopos Peninsula. Admixture analyses and isolation by distance tests confirmed the specific distinctness of A. grabusana, A. xanthostoma, A. amalthea and A. candida.