ABSTRACTBacterial symbionts that resembled mollicutes were discovered in the marine bryozoanWatersipora arcuatain the 1980s. In this study, we used PCR and sequencing of 16S rRNA genes, specific fluorescence in situ hybridization, and phylogenetic analysis to determine that the bacterial symbionts of “W. subtorquata” and “W. arcuata” from several locations along the California coast are actually closely related α-Proteobacteria, not mollicutes. We propose the names“CandidatusEndowatersipora palomitas” and “CandidatusEndowatersipora rubus” for the symbionts of “W. subtorquata” and “W. arcuata,” respectively.