Surprises from the Deep: New and Unusual Crinoids

A combination of new material and observations of deep-sea crinoids, chiefly from NOAA’s expeditions in the central and western Pacific, plus re-examined older specimens, has revealed a series of unexpected novelties, including range extensions for several taxa (e.g., Metacrininae and Holopodidae). A new species, and possibly genus, of the stalked family Phrynocrinidae previously seen in Indonesia, exhibits an arm branching pattern previously unknown among extant crinoids, and a pattern of stalk articulations apparently the inverse of its confamilials. In the Phoenix Islands Protected Area, Maibua Seamount supports a vast dense monospecific assemblage of featherstars in ~700-740 m, and an observation at 5770 m in Kinono Trough represents a new depth record for any featherstar. On Utu Seamount off Samoa, some adult-sized apparent featherstars retain a postlarval stalk shorter than their arm length. An apparently new species of Atopocrinus from off Japan bears cirrus sockets separated by large openings that appear to connect the centrodorsal cavity directly with the exterior; it more closely resembles a crinoid recently described from the Jurassic than any other extant genus. Specimens ostensibly belonging to two other featherstar genera, Thaumatocrinus and Psathyrometra , stretch their respective generic diagnoses. Sequence data from recently collected specimens is being added to an ongoing phylogenetic revision of extant Crinoidea.