Discorhabdella pseudaster n. sp. is an incrusting sponge from the upper bathyal zone of the 'Banc du Geyser', north of Madagascar, Mozambique Channel. This new species is described only from a single specimen but it is remarkable by the presence of spicules similar to euasters, a type of microsclere unknown in Poecilosclerida. These spicules are in fact a new example of homoplasy, being derivatives of the typical Discorhabdella pseudoastrose acanthostyles, which are here reduced to the aster-like tyles. The isochelae with a large lamella on the shaft are also quite unique in Poeciloclerida.
Keywords: Porifera, new species, Madagascar, bathyal, homoplasy.