Comparative shell morphology of the rare land snails Levantina ninivita and Levantina escheriana (Gastropoda: Helicidae) in south-eastern Türkiye

Abstract

This study examines and compares the morphological characteristics of 2 similar and rare land snails, Levantina ninivita (Galland, 1885) and Levantina escheriana (Bourguignat, 1864), from locations in south-eastern Türkiye. Shells of L. ninivita were collected in the autumn of 2023 in the villages of Mağaraköy, Sarıköy, Haberli, and Yayvantepe, which are approximately 85 km from the city centre of Şırnak. Levantina escheriana specimens were collected in the villages of Yardere, Ahmetli, Aytepe, and Konaklı, approximately 25 km from the city centre of Mardin. The terrain in all villages consists primarily of limestone rocks, and most specimens were collected among rocks, particularly in shaded areas. Shell morphology of these species is found to be very similar, but the peristome is affixed to the parietal wall in L. ninivita and detached from it in L. escheriana, as previous authors have indicated. Analysis of shell measurements of 120 shells per species revealed significant differences between collection sites for all measurements and significant differences between species in mean shell width (p = 0.012), spire height, and aperture size (both p < 0.001). however, there is a considerable overlap of all measurements, but key ratios, such as spire height/aperture height and aperture height/shell height, were effective in identifying individuals based on shape rather than size alone. therefore, this study makes a substantial contribution to the knowledge about Levantina species by providing comprehensive morphological and statistical analyses, facilitating precise species identification and supporting future conservation strategies.