The status of Otala punctata (Muller, 1774) : a recently established terrestrial gastropod in Malta

Abstract

A population of the alien helicid Otala punctata (Müller, 1774) has recently been found on the island of Malta (Central Mediterranean), located around a single plant nursery at Mosta in the central part of the island. Extensive field collections indicate that this species was very probably introduced via the horticultural trade and is gradually extending its range from its point of introduction, occupying a variety of natural and anthropic habitats. Analysis of size-frequency data suggests that Otala punctata has successfully bred through at least three consecutive reproductive events until 2006. We hypothesise that Otala punctata was originally imported accidentally with plant material and established itself in the nursery, from where it then escaped into the surrounding land since 2003. This situation represents the introduction of yet another alien species on Malta with the potential of becoming an agricultural pest, and a threat to the islands’ biodiversity.