New molluscs associated with biogenic substrates in Cenozoic deep-water sediments of Washington State

Abstract

Cenozoic deep−water sediments of the Lincoln Creek, Makah, and Pysht formations in western Washington State, USA, contain sunken driftwood and whale bones that were colonized by invertebrates which largely depend on this type of transient habitat. These fossil woodand whale−fall faunules yielded six new mollusk species that appear to have been endemic to these biogenic microhabitats, except for one species which also occurs in cold−seep limestones. The new gastropod species are the neomphalid Leptogyra squiresi, the buccinid Colus sekiuensis, the allogastropod Xylodiscula okutanii, and the new bivalve species are the protobranch “Nuculana” posterolaevia, the mytilid Idas? olympicus, and the heterodont Thyasira xylodia