| Summary: | This work describes Bryozoa of the order Cheilostomata associated with polymetallic nodules collected by box-coring in the eastern part of the Russian exploration area of the Clarion-Clipperton Fracture Zone (CCFZ or CCZ) under contract to Yuzhmorgeologiya. Study of 569 cheilostome specimens from 4510–5280 m depth yielded 32 species (22 new) in 20 genera (3 new) and 14 families (1 new). For six species, the nomenclature was left open (genus only) owing to the paucity of defining characters. One species with a costate frontal shield, possibly belonging to the otherwise monotypic Polliciporidae, clearly represents a new genus, but was not named, as it comprises only an ancestrula, one fully formed daughter zooid and a zooid bud. Four of the species we detected are known from the deep sea beyond the CCZ; Columnella magna and Acanthodesiomorpha problematica occur not only elsewhere in the Pacific Ocean but also the Atlantic Ocean, while Smithsonius quadratus was first described from the Kuril-Kamchatka Trench, and the authors have unpublished records of Smithsonius candelabrum n. sp. from the Magellan Seamounts and the Louisville Ridge. These records give hope that other CCZ bryozoan taxa may also occur elsewhere, offsetting local extirpation through nodule mining. Almost 63% (20 species) of CCZ Cheilostomata have a flexibly erect colony attached by one or several rhizoids (and/or the ancestrula has a proximal cuticular stalk-like portion). Ten other species have fixed-erect rigid colonies; only two species are encrusting. If a 50 mm height or spread is taken as the lower limit defining a megafaunal organism, then only C. magna qualifies as megafaunal. If 20 mm is taken as the lower size limit (definitions vary), then nine other species have the potential to be recognized in ROV-obtained images. The completion of this monograph allows a summary of all bryozoan data for the Russian sector of the CCZ. Altogether, 52 species are known from this area, totalling 1002 specimens from 437 stations. The most abundant and ...
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