Hartman, 1958b
Definition: Calcaronea with a skeleton composed exclusively of free spicules without calcified non-spicular re-inforcements (L. variabilis spics MCS) (Sycon ciliatum spics).
Remarks: Seven families are recognized based on the organization of the choanocyte chambers: Amphoriscidae, Grantiidae, Heteropiidae, Leucosoleniidae, Sycettidae, Staurorrhaphidae, and Lepidoleuconidae. The latter two families have no representatives in the area and will not be treated here.
Source: Borojevic et al. unpublished.
Families represented in the area:
Family Amphoriscidae: with a distinct cortex of tangentially placed tetractines; no choanosomal skeleton, but atrial skeleton always present.
Family Grantiidae: cortex of tangential spicules; choanoskeleton is regular; atrial skeleton is well-developed (syconoid aquiferous system).
Family Heteropiidae: continous cortex; distinct subcortical zone formed by pseudosagittal triactines; articulated choanosomal skeleton may be present or absent.
Family Leucosoleniidae: no cortex; continuous choanoderm that lines all of the internal cavity of the sponge (asconoid system).
Family Sycettidae: cortex is continous and strengthened by tangential spicules, but these do not cover the choanocyte chamber layer. Choanosomal spicules have an articulated arrangement; the ends of chambers project to a greater or lesser extent on the ectosomal surface (syconoid aquiferous system).