Topsent, 1904
Definition: Persistently encrusting Halichondrida, with single styles or rhabdostyles erect on a basal mass of twisted or flexuous spicules; the latter may be oxeote, strongylote or stylote, entirely msooth or provided with spines and or swellings (Bubaris vermiculata skel).
Remarks: This family is often included in the family Axinellidae with the reasoning that the basal mass of curved spicules was homologous to the condensed axis of branching sponges. However, since a number of persistently encrusting genera exist with such a basal mass of spicules, it is here regarded as evidence for monophyly. 9 nominal genera, with approximately 6 valid genera are presently included in the family.
The family may in future be merged with the Lithistid family Desmanthidae Topsent, 1893, since that family also shows a structure with styles erect on a basal mass of (desma)-spicules. If and when that is proposed, then the family Desmanthidae has priority.
Source Van Soest, unpublished.
Genera represented in the area:
Bubaris Gray, 1867 (type species: Hymeraphia vermiculata Bowerbank, 1866) (syn. Ommatosa de Laubenfels, 1936): choanosomal skeleton with a condensed reticulation of smooth flexuous or vermiform strongyles, sometimes only straight oxeas, with projecting bundles or individual styles ascending to the surface.
Bubaropsis Lévi and Vacelet, 1958 (type species B . curvisclera Lévi and Vacelet, 1958): encrusting growth form; choanosome is a condensed basal layer of spongin cored by scattered acanthostrongyles with tylote bases, lying adjacent to the substrate; extra-axial skeleton is disordered, without an obvious radial structure, containing scattered tracts of curved oxeas, sharply angular or toxiform oxeas, strongyles and raphides in bundles.
Cerbaris Topsent, 1898 (type species C . torquatus Topsent, 1898): encrusting growth form; choanosomal skeleton consists of a basal layer of spongin fibres cored by twisted, U-shaped, diactinal megascleres which are evenly acanthose, rarely smooth, often with strongylote points, and form a discrete but overlapping basal reticulation; extra-axial skeleton consists of smooth styles-subtylostyles, with subterminal swellings, standing perpendicular to the substrate, protruding through the surface.
Hymerhabdia Topsent, 1892 (type species H . typica Topsent, 1892a): encrusting growth form; choanosomal skeleton consists of a basal layer of spongin fibres on the substrate, without coring megascleres, but with extra-axial styles-tylostyles, or sometimes oxeas, and rhabdostyles erect on basal layer and protruding through the surface.
Monocrepidium Topsent, 1898 (type species M . vermiculatum Topsent, 1898) (syn. Skeizia Cabioch, 1968): encrusting growth form; choanosomal skeleton consists of a basal layer of globular or granular, vermiform, diactinal monocrepidial desmas; with extra-axial styles or rhabdostyles embedded in basal spongin, perpendicular to substrate, and protruding through the surface; mesohyl contains more slender diactinal, vermiform megascleres than those of the axis.
Rhabdoploca Topsent, 1904 (type species Microciona curvispiculifera Carter, 1880): laminate encrusting growth form; choanosomal skeleton consists of a condensed basal layer of spongin, with acanthose curved strongyles, with aspinose bases, standing erect; extra-axial skeleton consists of long smooth rhabdostyles embedded in and perpendicular to the basal layer, projecting through the surface, interdispersed with echinating smooth rhabdostyles; mesohyl contains acanthose strongyles distributed without apparent order.
Species included:
Bubaris vermiculata
Hymerhabdia intermedia
Hymerhabdia typica
Monocrepidium minutum
Species not included:
Bubaropsis curvisclera Lévi and Vacelet, 1958, North Atlantic, deep water
Cerbaris torquatus Topsent, 1898, North Atlantic, deep water
Monocrepidium vermiculatum Topsent, 1898, North Atlantic, deep water
Rhabdoploca curvispiculifera (Carter, 1880), North Atlantic, Azores, deep water