Two Introduced Cepaea Species (Gastropoda, Helicidae) in Ternopil, Western Ukraine, and Specifics of Their Phenotypic Composition

Abstract

The shell colour and banding polymorphism of Cepaea was studied at 6 sites of Ternopil. Cepaea hortensis was found at all sites, its cohabitation with C. nemoralis was recorded in three cases. Phenotypes were determined in 1166 adult snails or empty shells with well-preserved colouration (830 C. hortensis, 336 C. nemoralis). It was found that part of the areas in Ternopil, as well as in the neighbouring Lviv Region, is inhabited by descendants of the primary introduction of C. hortensis to Western Ukraine with reduced variability in the shell colouration and only with a light body. At four studied sites, colouration traits indicating the presence of later introductions of C. hortensis were found: yellow banded shells, less often pink ones and well-expressed variability in body colouration. The phenotype 10305 in C. hortensis, previously unknown from Ukraine was shown. A significant negative correlation between the yellow shell colour and the band presence in C. nemoralis was found at one site, which is not typical for Western Ukraine and also rare in other introduced Eastern European populations of this species. The potential significance of the results for documenting the introduction history of two Cepaea species into Ukraine is discussed.