Marine Biodiversity » Marine Sponges » Calcarea » Calcarea Classification » Subclass Calcaronea

Definition: Solitary, tubular sac-shaped growth forms with well-developed spicule fringe around terminal oscule; continuous cortex covers the choanosome, perforated by ostia; ectosomal tetractines never present, and tangential atrial skeleton present only in oscular region; subatrial quadriradiates ('chiactines') present and equiangular; symmetrical and asymmetrical triradiates and oxeas scattered freely within choanosomal skeleton, projecting through cortex; aquiferous system is syconoid or leuconoid

Scope: Two genera.

Reviews: Dendy & Row (1913), Burton (1963) and Borojevic (1968).

Genera:
Achramorpha Jenkin, 1908 (type species: Achramorpha truncata Topsent, 1907) - thin-walled tubular, apical oscule with well developed marginal fringe; skeleton of chamber layer composed of basal rays of choanosomal radiates and, usually of proximal parts of radial oxeas; choanosomal skeleton of paired and apical rays of subgastral triradiates and quadriradiates, with sometimes a tangential layer of quadriradiates (or triradiates); ectosomal skeleton, when present, a tangential layer of triradiates or quadriradiates (Burton, 1963).
Megapodon Jenkin, 1908 (types species: Leuconia crucifera Poléjaeff, 1883) - unknown shape, hispid surface; ectosomal skeleton a tangential layer of triradiates, with oxeas and trichoxeas projecting from the surface; skeleton of chamber layer of centrifugally-directed basal rays of subgastral sagittal quadriradiates, together with scattered triradiates; choanosomal skeleton of quadriradiates (Burton, 1963).