Is Chondrula tridens (Müller, 1774) an invasive snail species in Lithuania?

Abstract

The aim of the present paper is to answer the question whether the species is invasive or not and describe the studied peculiarities of the Lithuanian population of the species: 1) distribution pattern; 2) relation to vegetation; 3) land snails’ community composition in the studied sites. All literature data about the distribution of this species in Lithuania is reviewed. Research was made in 17 sites in August of 2010, 2011 and 2012. New data on four sites of Chondrula tridens (Muller, 1774) by the railway line Kabeliai–Visaginas are given. The results showed that the species is rare, and has fragmented distribution related to urbophytocenoses, in the vegetation from class Festuco-Brometea Br.-Bl. et Tx. 43 and its natural alliances, that are really relict because vegetation belongs to steppe-flora of Holocene. There is a possibility that C. tridens (Muller, 1774) could have inhabited Lithuania in Holocene. On the whole 30 species were determined. Spearman Rank Order Correlations test showed that the species has a weak significant negative correlation (r = –0.3) with Pupilla muscorum (Linnaeus, 1758) and slightly more positive correlation (r = 0.4) with Nesovitrea hammonis (Strom, 1765), Euomphalia strigella (Draparnaud, 1805) and Helix pomatia Linnaeus, 1758. The fact that H. pomatia Linnaeus, 1758 is an introduced species to Lithuania and C. tridens (Muller, 1774) was found by the railway proves that species distribution has an anthropogenic character, i. e. is related to human activities. We can conclude that the origin of C. tridens (Muller, 1774) in Lithuania is unclear but there is no threat of its invasion.