A new species and a new subspecies of Amphidromus from Atauro Island, East Timor (Gastropoda, Pulmonata, Camaenidae)

摘要

Amphidromus (Syndromus) richardi spec. nov. and A. (S.) richardi manacocoensis subspec. nov. are described from the island of Atauro, East Timor, Lesser Sunda Islands. Zoogeographic and habitat information are given. The new taxa are compared with theAmphidromus forms living on the nearby islands of Wetar, Alor and Timor. A colour plate illustrates individual characteristics for the Amphidromus taxa discussed. The range of Amphidromus Albers, 1850, stretches from Assam, India to the Northern Territory of Australia, but only in the islands of the Banda Arc is the genus found on true oceanic islands. It is on these isolated islands that the genus radiates into some of its most distinctive forms. Atauro is one of these oceanic islands. There is dry lowland forest along most of the coast and an area of rain forest capping the summit of 1,000 m Mana Coco Mountain at the island's southern end. The Amphidromus described below are found in the dry coastal forest of the north and west and on the damp summit of Mana Coco. The two forms appear to be completely isolated from one another by a lack of suitable habitat. This isolation appears to have allowed morphological divergence in the shells of the two populations, possibly in response to the availabilityof water.