Studies on western Atlantic Octocorallia (Coelenterata: Anthozoa). Part 6: The genera Primnoella Gray, 1858; Thouarella Gray, 1870; Dasystenella Versluys, 1906

The seven western Atlantic species belonging to three genera, Primnoella, Thouarella, and Dasystenella, are described and illustrated. Three new species of Thouarella are described, which constitute the first records of this genus for the northwestern Atlantic. An annotated and revised list of the 26 species of Thouarella is given. Most of the species included occur primarily in the southwestern Atlantic at depths of 50–5000 m; however, one species, Thouarella grasshoffi, is amphi-North Atlantic in distribution. Whereas most of the species included herein are small and inconspicuous, T. grasshoffi is fairly large and occurs abundantly on seamounts of the New England Seamount Chain as well as on eastern Atlantic seamounts. Specimens of all three genera are still relatively rare in museum collections.