The provenance of the Greek land snail species Isabellaria pharsalica : molecular evidence of recent passive long‐distance dispersal

Aim

The slowly dispersing Greek land snail species Isabellaria (Carinigera) pharsalica (Nordsieck, 1974) can be readily distinguished from related species of the subgenus Carinigera on biogeographical grounds, i.e. by a separation of nearly 200 km. Nevertheless, I. pharsalica shows overlap in shell morphology with Isabellaria (Carinigera) buresi (A. J. Wagner, 1927). The aim of this paper is to study the interrelationships and phylogeography of I. pharsalica and selected I. buresi subspecies, in order to reconcile these apparently contradictory observations.

Location

Northern Greece, Macedonia, Serbia and southern Bulgaria.

Methods

Mitochondrial COI genealogical interrelationships were studied for specimens of I. pharsalica, selected I. buresi subspecies and other related Isabellaria species.

Results

COI sequences of I. pharsalica constitute a clade nested among sequences of I. buresi from north-eastern Greece and adjacent Bulgaria. The genetic divergence among the I. pharsalica sequences is remarkably low compared to the divergence among the I. buresi sequences.

Main conclusions

I. pharsalica descended from specimens of I. buresi that dispersed into Thessaly, and it should therefore be classified as a subspecies within I. buresi. This find is in line with the conchological similarities between I. buresi pharsalica and other I. buresi subspecies. Given the low vagility of the snails in question and the c. 200-km separation by land and sea between the ranges of I. buresi pharsalica and the combined range of the other I. buresi subspecies, passive dispersal of the I. pharsalica ancestors is most likely. Since the inferred area of origin of these hypothetical ancestors of I. buresi pharsalica nearly coincides with an ancient marble quarry, human-aided dispersal during marble transport offers a possible explanation for I. buresi pharsalica's erratic distribution.