Is the endemic Maltese Top-shell Gibbula nivosa extinct?

Abstract

The trochid gastropod Gibbula nivosa, endemic to the Maltese Islands, has recently only been found in two Maltese bays, where it occurred on seagrass leaves and under stones at depths of 1-4m. Intensive sampling of Cymodocea nodosa and Posidonia oceanica meadows, sediment and pebbles at depths of 2-12m, carried out in 2000 and 2002, resulted only in empty shells but no live animals, suggesting that the species is extinct from these localities where previously good populations were found. However, the occurrence of fresh shells from other Maltese sites suggests that small undiscovered populations may exist. G.nivosa is considered to be ’critically endangered’.