Classification of somasteroids and asteroids (Asterozoa: Echinodermata)

Abstract

The basic asterozoan stock, the Somasteroidea, is characterised, among other features, by the absence of an odontophore. In the Asteroidea, characterised among other features by the presence of an odontophore, two superorders are here recognised. One includes those asteroids lacking a brachiolarian larval stage, without suckered tube-feet and with the madreporite not incorporated into the calyx. The other includes those asteroids with a branchiolarian larval stage—unless suppressed by direct development—with suckered tube-feet and with the madreporite associated with a primary interradial plate (basal). Recognition of these features permits—