Rediscovery of Leptaxis vetusta (Morelet & Drouet, 1857), a subfossil land snail from the Quaternary of Santa Maria (Azores)

Abstract

Key.words: Late Pleistocene; Holocene; terrestrial gastropods; Santa Maria; Azores. During a recent field work: on the southern coast of the island of Santa Maria (Azores) a bulk sample of 37 shells and 25 fragments of Leptaxis vetusla was assembled from Late Pleistocene and Holocene slope deposits outcropping in the area. These specimens are the first of this rare subfossil species to be mentioned since the original descriptions of Arthur Morelet and Henri Drouet (1857). The purposes of our paper are a systematic and biometric description of L. vetusta. For the first time, the original type locality was localized with accuracy over the southern downslopes of Pico do Facho, between Figueiral and Prainha. The subfossil specimens were collected in slope deposits and detritic fans. overlying a fossiliferous marine deposit situated over the 2-3 m abrasion platfornm of Praia and Prainha bay. The age and factors associaled to the extinction of this species are discussed, including the destruction of the original laurel cover and the colonization by Otala lactea (Muller, 1774), a continental helicid introduced and widespread in Santa Maria.