A revision of the Zenometridae (new rank) (Echinodermata, Crinoidea, Comatulidina)

Three genera of unstalked crinoids, Zenometra, Sarametra and Psathyrometra, formerly included in the subfamily Zenometrinae of the family Antedonidae, are removed and placed in a distinct family, the Zenometridae. Diagnostic features include a cavernous centrodorsal cavity, a complete basal circlet with a large central lumen and cirrus sockets with a concave fulcral bowl a round the lumen. Sarametra nicobarica is synonymized under S. triserialis, which is redescribed in detail. Psathyrometra is redefined and includes onl y the species P. fragilis, P. congesta and P. bigradata, which are redescri bed. P. erythrizon is synonymized under P. fragilis. The four other species formerly included in Psathyrometra are removed to Athrypsometra gen. n., r etained in the Antedonidae. The other genera formerly included in the Zenom etrinae are considered incertae sedis in the family Antedonidae pending det ailed re-examination. Cladistic analysis using the antedonids, Poliometra p rolixa (a former zenometrine) and Florometra serratissima, and the thalasso metrid, Oceanometra annandalei, as outgroups produces the following tree: ( O. annandalei((F. serratissima/P. prolixa)(((P. fragilis/P. congesta)P. big radata) (S. triserialis/Z. columnaris)))).