On the affinities of three small sea-star families

Abstract

The Metrodiridae, Mithrodidae and Valvasteridae are monogeneric sea-star families of obscure affinities traditionally assigned to the generically and morphologically diverse order Spinulosida. Re-valuation of available information, combined with the use of new skeletal characters, has led to reassignment of Metrodira to the spinulosan family Echinasteridae, Mithrodia to the valvatan family Ophidiasteridae, and Valvaster to the family Asteropseidae. The Asteropseidae is in turn assigned to the order Valvatida.