Abstract
The introduction of Grandidierella japonica Stephensen, 1938 (Corophiidae) from Japan to Tomales Bay, Bolinas Lagoon and San Francisco Bay, California, is recorded for the first time. A diagnosis and a list of associate species are given. The possible synonymy of the genera Grandidierella and Neomicrodeutopus is indicated. This species probably arrived with oyster spat transplants from Japan.
