Weak overturning circulation and high Southern Ocean nutrient utilization maximized glacial ocean carbon

Muglia, Juan; Skinner, Luke C.; Schmittner, Andreas

doi:10.1016/j.epsl.2018.05.038

A large collection of scalibregmatid polychaetes has been assembled from offshore monitoring and reconnaissance surveys conducted in the Western North Atlantic Ocean, Gulf of Mexico, Eastern North Pacific Ocean, Southern Ocean, and South China Sea. The materials from these projects and others from several museum collections have yielded specimens from ten genera and 76 species, of which 54 are new to science. The type species of the genera Asclerocheilus, Axiokebuita, Oligobregma, Scalibregmella, Sclerobregma, and Mucibregma are redescribed either from type material and/or specimens from near the type locality. The type-species of Axiokebuita (A. millsi) is revalidated and redescribed based on new material off eastern North America. Scalibregma brevicaudum Verrill, 1873 is revalidated based on the holotype from Long Island Sound and numerous new collections from northeastern North America. The ten genera treated are as follows: Asclerocheilus 16 species with 12 new to science; Axiokebuita six species with three new to science; Hyboscolex six species with five new to science; Oligobregma 14 species with 11 new to science; Parasclerocheilus one new species; Pseudoscalibregma eight species with five new to science; Scalibregma 19 species with 15 new to science; Scalibregmella two species with one new to science; Sclerobregma two species with one new to science, and Mucibregma, one species. Most new species are from offshore or deep-water habitats and, except in areas with a history of extensive monitoring, are represented by relatively few individuals. Known species of each genus with five or more species are tabulated, compared, and reviewed. The depth intervals of all scalibregmatids are tabulated in order of increasing depth. Lists of deep-water scalibregmatids are updated. Of 141 known species of Scalibregmatidae, 73 or 52 % occur in depths of 1000 m or greater. Of the 54 new species included in this report, nine occur from the intertidal to 100 m; four occur from 100 to 500 m; six occur from 500 to 1000 m; and 34 species or 63% occur in depths greater than 1000 m, with 12 of these ranging into abyssal depths of ~3000 m or deeper. The status of Mucibregma spinosa Fauchald & Hancock, 1981 is reviewed and, although poorly preserved and damaged, is confirmed as a species of Scalibregmatidae, albeit unique with acicular spines on all parapodia. The holotype of the enigmatic deep-water genus and species Neolipobranchius glabrus Hartman & Fauchald, 1971 is demonstrated to be an indeterminate juvenile of the genus Travisia and, with the genus becoming a junior synonym of Travisia, the species is declared a species inquirenda.

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