Nonmarine Mollusks from Archaeological Sites on Tikopia, Southeastern Solomon Islands

Abstract

Eighteen species of nonmarine mollusks are recorded from the island of Tikopia, southeastern Solomon Islands. Material studied was obtained from eight archaeologica l sites; a small sample of live-collected specimens was also examined. Fifteen species of terrestrial mollusks were pre sent in this material: six are believed to be indigenous to the island (although none is precinctive to it), eight were introduced by humans, and the status of one is uncertain. Three additional species inhabiting estuarine, strandline, or aquatic environments were found . The terrestrial mollusks of Tikopia are typically New Hebridean, although prosobranchs and large pulmonates are poorly represented in the fauna. Radiocarbon dates associated with several of the archaeological samples demonstrate that most of the adventive species colonized the island during the prehistoric period: Lamellidea pusilla, Gastrocopta pediculus, and Lamellaxis gracilis were present on the island by ca. 900 B.C., and by ca. A.D. 1400 Liardetia samoensis, Wilhelminaia mathildae, and Coneuplecta microconus had become established . Two exotic subulinids have been introduced during the modern era. The numerical predominance in all archaeological samples of individuals of adventive species indicates that the Tikopian environment was significantly modified by humans during the prehistoric period, probably as a result of agricultural practices.