Definition: Encrusting, massive, lobate, or more frequently spherical and tubular growth forms buried in the substrate, usually with fistules on upper surface bearing apical oscules, occasionally excavating coralline substrates. Ectosomal skeleton is a multilayered, irregular, tangential reticulation of diactinal spicules (oxeas or strongyles), forming a distinct, usually detachable, parchment-like crust. Choanosomal skeleton is an irregular reticulation of diactinal spicules forming multispicular tracts, typically producing a pulpy effect, with or without spongin fibres, together with an irregularly dispersed isotropic reticulation of single spicules scattered between these major tracts. Microscleres may include centrangulate sigmas and toxas (Oceanapia robusta draw).
Remarks: There are 10 nominal genera, with only five presently included in this family. See also Van Soest (1980), de Weerdt (1985).
Source: Desqueyroux-Faúndez & Valentine, 2002c.
Genera represented in the area:
Aka De Laubenfels, 1936 (type species: Acca infesta Johnson, 1899) (synonym: Siphonodictyon Bergquist, 1965): excavating sponges with fistules outside the substrate and pulpy /slimy choanosome within chambers in the substrate. Some authors consider this to be a member of Niphatidae.
Calyx Vosmaer, 1887 (type species Spongia nicaensis Risso, 1826) (syn. Lieberkuehnia Balsamo-Grivelli, 1860): no fistules; crust of tangential oxeas in single spicule reticulation; choanosome an isodictyal single spicule reticulation with long irregular spicule tracts traversing the body.
Oceanapia Norman, 1869 (type species: Desmacidon jeffreysi Bowerbank, 1866) (syn. Rhizochalina Schmidt, 1870; Phloeodictyon Carter, 1882; Biminia Wiedenmayer, 1977): long aquiferous fistules on upper surface; spongin-enforced tangential ectosomal crust composed of single spicules or paucispicular tracts in isodictyal or irregular (isotropic) arrangement; fistule walls in particular are supported by an irregular isotropically meshed reticulation of spicule tracts bound by spongin; choanosomal skeleton often pulpy, with multispicular tracts of spicules, with our without single spicules dispersed between major spicule tracts; microscleres may include sigmas and/or toxas (modified from Bergquist and Warne, 1980; van Soest, 1980).
Species not treated here:
Aka coralliophaga (Stephens, 1914), Ireland, deep water (suspected contamination)
Oceanapia elongata (Topsent, 1904), Ireland, deep water
Calyx tufa (Ridley and Dendy, 1886), NW Spain, W Africa, deep water