Family Calthropellidae Lendenfeld, 1907

Abstract

Calthropellidae Lendenfeld (Demospongiae, Astrophorida) is a small family of Astrophorida positioned between the major families Ancorinidae and Pachastrellidae. With Ancorinidae (Geodiidae) they share the possession of euasters, and with Pachastrellidae they share calthrops-like megascleres. There are no unique features, and it is suspected that the family may turn out to be artificial. All genera have calthrops and euaster microscleres, and some have modified triaenes and tetractines, mesotriaenes (mesocalthrops or mesodichotri-aenes) and oxeas. Genera are differentiated by the presence or absence of oxea megascleres, organisation of triaenes in the choanosomal and subectosomal skeletons, and euaster morphology and diversity. Four valid genera are recognised and only about two dozen species worldwide, with records from the North Atlantic, Mediterranean, South Africa, western Indian Ocean, Indonesia and New Zealand, found mainly in warmer waters, moderately deep (about 600 m) but also recorded occasionally from the littoral.