Sphenophrya dosiniae is a gill symbiont of infaunal bivalve mollusks, known from the introduced NW Atlantic Mya arenaria, the native NE Atlantic Dosinia exoleta, Corbula gibba, Timoclea ovata, the NW Atlantic native Spisula solidissima, and the NE Pacific native Cryptomya californica (Kozloff 1946; Fenchel 1965; Cohen and Carlton 1995). However, this species is mentioned for San Francisco Bay, but in one sentence, with no details