Monophyly of the Porifera

Abstract

The monophyly of the Porifera is weil established. According to our hypothesis the Hexactinellida are the adelphotaxon of the Pinacophora (new taxon = Calcarea + Homoscleromorpha + Demospongiae). The Porifera are the adelphotaxon of the Eumetazoa/Placozoa. Sponge spicules are considered not to be a constituent character of the Porifera. Mineralized spicules developed independently within the three poriferan main taxa the Hexactinellida, Calcarea, and Demospongiae. Demospongian microscleres are not derived from megascleres in contrast to those of Hexactinellida. Accordingly, spicules probably developed several times within the Demospongiae. Remains of Porifera are known since the late Proterozoic.