A revision of the supraspecific classification of the subclass Calcaronea (Porifera, class Calcarea)

A revision of all the genera of the subclass Calcaronea (Porifera, Calcarea) is given. In addition to the two previously described orders, Leucosoleniida Hartman, 1958 emend. and Lithonida Vacelet, 1981, we recognize a thirdone: the Baeriida. The order Leucosoleniida includes nine families, one of which is new (the Jenkinidae), and 42 genera of which four are new (Breitfussia, Leucandrilla, Polejaevia and Syconessa). The order Lithonida includes two families and six genera. The order Baeriida includes three families of which two are new (the Baeriidae and the Trichogypsiidae), and eight genera. The Leucosoleniida seem to have evolved from the olynthus grade, a form that is probably present in the early stages of ontogenesis of all Leucosoleniida and subsists at the adult stage in Leucosolenia. The Leucosoleniida comprises a diverse group with several pathways of progressing complexity of form, starting with sponges of a simple sycettid organization and leading to sponges with a complex aquiferous system and skeleton. Increase in size from the sycettid grade of organization may occur by two different processes: 1) the growth and elongation of radial tubes increasing the thickness of the sponge body (seen in the Sycettidae-Grantiidae line and the Heteropiidae), or 2) the growth of the central tube containing the atrial cavity which increases the length of the sponge body (seen in the Jenkinidae and the simple forms of Amphoriscidae). The sponges classified in the Baeriida and the Lithonida have very divergent forms that are represented by only a few living species. Identification keys and illustrations are provided for all the valid genera.