Bockeliecrinites, a new name for Protocrinites rugatus Bockelie, 1984 (Diploporita, Blastozoa), and its taxonomic significance

As part of a broader study of the family Protocrinitidae, all specimens of ‘Protocrinites’ rugatus Bockelie, 1984, have been examined. The species differs significantly from Protocrinites oviformis Eichwald, 1840, type species of Protocrinites s.s. and is proposed as type species of a new genus Bockeliecrinites. Bockeliecrinites has an aboral cup composed of a single, conical, centrodorsal plate above which is a closed circlet of five, inter-radial, lateral plates. All species of Protocrinites have an aboral cup with closed two circlets of at least four plates. Food grooves extend beyond the last brachiole-bearing adambulacral plate. As a result, lateral branches to brachioles did not always develop in the same order as the adambulacral plates themselves. Bockeliecrinites lived in a distal environment with frequent turbidite deposits and its preservation shows that some specimens were buried alive. Delicate structures such as brachioles and stem remain attached to thecae. Cover plates of food grooves, mouth, anus and respiratory diplopores are all preserved in some specimens. The last have never been reported before in any diploporite. Bockeliecrinites was probably derived from the ‘eocrinoid’ Rhopalocystis Ubaghs, 1963, with which it shares a centrodorsal plate and cover plates to its respiratory epispires. The lineage may extend back to the Cambrian genera Peridionites Whitehouse, 1941 and Cymbionites Whitehouse, 1941. If so, both ambulacralian and anambulacralian diploporites had a common origin and the class Diploporita may be monophyletic.