PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 112(2):313-318. 1999. Striatodoma dorothea (Cheilostomatida: Tessaradomidae), a new genus and species of bryozoan from deep water off California Judith E. Winston and Stace E. Beaulieu (JEW) Virginia Museum of Natural History, Martinsville, Virginia 24112, U.S.A.; (SEB) Marine Biology Research Division, Scripps Institution of Oceanography, La Jolla, California 92093-0202, U.S.A. (Current address) Applied Ocean Physics and Engineering Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, U.S.A. Abstract — Striatodoma dorothea, a new genus and species of cheilostomate bryozoan, is described from material found attached to hexactinellid sponges and pogonophoran tubes at an abyssal station (4100 m depth) off central Cal-ifornia. Members of this new genus can be distinguished from other members of the family Tessaradomidae by the presence of biserial, rather than quadris-erial branches, and a peristomial sinus, rather than an enclosed spiramen. Two other Pacific species, Diplonotos striatum Canu & Bassler, 1930, and Tessar-adoma bifax Cheetham, 1972, are transferred to Striatodoma. Although bryozoans have been identified from deep-sea stations down to 8300 m, re-views by Schopf (1969) and Hay ward (1981) have shown that only a tiny portion of the deep ocean floor has been sampled for the group. Nothing is known of the deep-sea bryozoan fauna of the eastern Pa-cific with the exception of three species found at two stations in the eastern Pacific between Acapulco and Panama during the Galathea Expedition (Hayward 1981). Re-cently, as part of a study by Beaulieu (1998) of hard substrate epifauna at abyssal depths off California, an attempt was made to identify all taxa attached to biogenic structures that protruded from the soft sed-iment of the sea floor. Individual stalks of the hexactinellid sponge Hyalonema sp. and individual tubes of the pogonophoran Uni-brachium sp. were sampled in tube cores using the submersible Alvin at 4100 m depth. Two of the approximately 140 spe-cies found attached to the sponge stalks and pogonophoran tubes were bryozoans. One is a ctenostome, Arachnidium hippothooi-des Hincks, 1862. The other is an undes-cribed genus and species of deep-sea chei-lostome which we name and describe be-low. Tessaradomidae Jullien, 1903 Striatodoma, new genus Diagnosis. — Tessaradomidae character-ized by subcylindrical, proximally thick-ened branches with two series of zooids, longitudinally striated calcification, a spi-ramen in close association with zooid peri-stome, rows of marginal pores, some of them replaced by oval avicularia, and a subglobular imperforate ovicell. Striatodo-ma differs from Tessaradoma in possessing branches made up of two, rather than four series of zooids, and in confluence of the spiramen with a peristomial sinus. Type species. — Striatodoma dorothea, new species, by present designation. Additional species of Striatodoma. — Tes-saradoma bifax Cheetham, 1972 and Di-plonotos striatum Canu & Bassler, 1930. Etymology. — The first part of the genus name is from the Latin, striatus = fur-rowed, channeled, descriptive of the striated appearance of colony walls. The second
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