Family Axinellidae Carter, 1875

Abstract

Axinellidae Carter (Demospongiae, Halichondrida) contains 10 valid genera (of 90 nominal genera) and approximately 300 species described so far worldwide. The family has a wide distribution from shallow to deep waters (down to 1800m depth). Species are generally erect, branching, fan-shaped or tubular, but encrusting and massive forms also occur. Species have no specialised ectosomal skeleton. The choanosomal skeleton is generally differentiated in axial and extra-axial regions with two basic types of skeletal architecture: (1) ascending and anastomosing spicule tracts, spongin fibres cored with spicules or fibrofascicles radiating to the periphery and ending in surface processes; (2) plumose to plumoreticulated. The axial skeleton of some species is either compressed or absent. Megascleres are styles, oxeas (and transitional forms) and sinuous strongyles in any combination. Bubaridae is excluded from synonymy with Axinellidae and reinstated as a valid taxon in Halichondrida.