A NEW CHEILOSTOME BRYOZOAN GENUS PSEUDOPLANKTONIC ON MOLLUSKS AND ALGAE

The little-known bryozoan Membranipora eburnea HINCKS is redescribed a nd designated the type species of the new genus Jellyella. The twinned ancestrula of this malacostegan-grade cheilostome places it within th e Membraniporidae, along with Membranipora and Biflustra. Jellyella is distinguished by the presence of intricately branched processes (spin ules) projecting into the zooidal chambers, and a calcitic skeletal ul trastructure of transversely arranged, elongate spindles. The ''Gulf w eed bryozoan,'' Membranipora tuberculata (BOSC), is also assigned to t he new genus as Jellyella tuberculata. Both species of Jellyella seem primarily to encrust floating substrates: based on available museum ma terial, J. eburnea usually grows on drifting shells of dead individual s of the cephalopod Spirula but can also be found as an epizoan of the floating gastropod Janthina and on algae; J. tuberculata is normally an epiphyte of Sargassum. Collections of Spirula shells from beaches a round the Indian, Pacific, and Atlantic Oceans are commonly encrusted by J. eburnea but very seldom by any other bryozoans. Jellyella is the refore interpreted as a rare example of a pseudoplanktonic genus among the typically benthic bryozoans.