Suborder Latrunculina subord. nov. incertae sedis

Abstract

Latrunculiidae Topsent (Demospongiae, Poecilosclerida) is assigned as a monophyletic taxon to suborder Latrunculina subord. nov., incertae sedis within Poecilosclerida. Latrunculiidae lacks any of the major apomorphies of this order but has certain other characters indicative of closer affinities with Poecilosclerida than with Hadromerida, to which it has previously been assigned. Latrunculiidae are unique amongst Poecilosclerida in having discate canthose microrhabd microscleres (acanthodiscorhabds, or chessman spicules) arranged vertically in a palisade on the exterior surface forming an ectosomal crust. The inferred homology between acanthodiscorhabds and spirasters of Hadromerida is rejected, as is their homology with spinose microrhabds (spinorhabds) found in Podospongiidae.