Family Merliidae Kirkpatrick, 1908

Abstract

Merliidae Kirkpatrick (Demospongiae, Mycalina) is a monogeneric family of poecilosclerids with a ‘sclerosponge’ body plan. The cal- careous basal skeleton of the single genus Merlia Kirkpatrick, 1908d has a distinct ‘chaetetid’ architecture and the mineral composition is high magnesium calcite. The poecilosclerid affinity is evident from the siliceous spicules, particularly the unique microscleres called cla- vidiscs, which bear structural resemblance to hamacanthid diancistras. Other spicular features, such as the possession of tylostyles and commata-like raphides indicate relationships with desmacellid sponges. Thus, the family is assigned to the poecilosclerid suborder Mycalina. Five species of Merlia have been named, including one fossil. Some species lack either the calcareous basal skeleton or the clavidiscs.