Aaptos pernucleata (Carter, 1870) Hadromerida, Suberitidae Common names: None. Growth Form: Massive encrusting, sprawling, cushion-shaped, occasionally lobate; up to 7 cm thick; lateral expansion ~10 cm but may be larger. Surface: Smooth, velvety, faintly hispid; often partly covered by sediment. Color: Purplish black, cream inside. Color remains in alcohol, but inside color becomes slightly darker. Consistency: Firm, tough, hard, and slightly compressible; cheese-like inside. Exudate: None. Oscules: Few, inconspicuous, scattered, occasionally on top of lobes, flush, ~0.5 cm across. Skeletal components (Spicules, fibers): Straight smooth rods slightly tapering toward both ends, with one end pointed, the other bluntly rounded with a slight bulge near the tip (strongyloxea); the wide size range (250-1400 x 2-40 μm) appears to consist of three overlapping length categories: ~1000-1400, 400-800 and 250-350 μm. The smallest spicules are concentrated peripherally. Spongin only binds spicules together; no distinct fibers. Skeletal Architecture: Spicules tend to occur perpendicular to the surface (radiate structure), especially at the periphery where smaller spicules form a palisade with their points outward. However, many spicules are confusedly arranged. Ecology: On rocks in lagoons and on deep reefs. Distribution: South Florida, Bahamas, Virgin Islands, Jamaica, at least down to 70 m. Notes: Hard, black cushions with a smooth surface and inconspicuous oscules are diagnostic, but low growing forms of several black species may be similar: Spheciospongia vesparium (oscules in groups), Tectitethya crypta (warty surface, black inside), and Neopetrosia carbonaria (brittle, also black inside). Other black species such as Spongia spp. and Halichondria melanodocia are soft, compressible or easily damaged. Closely related Aaptos duchassaingi is distinguished by its brown color and shorter relatively fat spicules; in other aspects it is similar. Reference(s): Carter (1870, as Trachya pernucleata); de Laubenfels (1953, as Prostylissa spongia); Wiedenmayer (1977, Epipolasis lithophaga). Similar species: Spheciospongia vesparium Neopetrosia carbonaria Aaptos duchassaingi Spongia pertusa