The origins of the heliciculture stock known as ‘ Helix aspersa maxima ’ ( Cornu aspersum ; Gastropoda, Helicidae) are obscured by its extremely elevated mitochondrial substitution rate

The origins of the large form of the land snail Cornu aspersum known in the snail breeding industry as ‘Helix aspersa maxima’ remain enigmatic. Here, we tested the hypothesis that it is a distinct subspecies of C. aspersum, which represents a mitochondrial lineage sister of all remaining haplotypes in this species. We analysed 2-gene and mitogenomic alignments of a representative set of C. aspersum lineages. We show that there is no evidence for a split between ‘maxima’ and the typical C. aspersum in the mitochondrial data. Instead, the sister relationship recovered in an earlier study was a phylogenetic artifact caused by an extremely elevated mitochondrial substitution rate of ‘maxima’. The sequences of ‘maxima’ are in fact nested among those of typical C. aspersum. Based on the origin of the sequences most similar to that of ‘maxima’, and considering available information on the origins of its heliciculture stock, we suggest that ‘maxima’ in the sense of a large-bodied C. aspersum with black mantle margins has originated from the northeast of Morocco.