Mycale (Aegogropila) sp. Poecilosclerida, Mycalidae Common names: None. Growth Form: Thinly encrusting, as little as a few millimeters thick, closely adhering to the substrate; as little as a few cm across. Surface: Smooth, porous. Partly covered with sand and sometimes partly overgrown by other sponges and worm tubes. Color: Red, orange. Consistency: Soft, fragile. Exudate: None. Oscules: Not readily visible, inconspicuous or absent. Skeletal Components (Spicules, Fibers): Smooth rods with one end rounded and slightly swollen, the other pointed (mycalostyle), 230-290 x 6 μm. Three types of microscleres: curved shaft with unequal blades (anisochela) spanning a wide size range (15-66 μm long) in three size categories; C-shapes (sigma) 77-114 μm long, possibly in two size categories, and bow-shapes (toxa) spanning a wide size range (66-250 μm). Skeletal Architecture: Exterior skeleton consists of intercrossing spicule bundles forming a network with small spicules strewn between them. Interior skeleton is an irregular meshwork of bundles of large spicules, often interconnecting, of variable mesh size, with most bundles directed towards the surface. Ecology: In shallow bays and lagoons. Distribution: South Florida; not known from elsewhere. Notes: Thin red crusts without clear surface markings are diagnostic. Other red encrusting species have rounded pore fields (Phorbas amaranthus) or distinct canal systems converging on oscules (Monanchora arbuscula, Spirastrella coccinea). Juvenile Clathria species often start as thin red or orange crusts, but usually have a bumpy surface and/or converging canal systems. Mycale laxissima differs in shape (large tubes or massive lobes), surface characters (spiky-conulose), and spicules (no toxas). Hajdu & Ruetzler (1998) reviewed Caribbean Mycale species, but recorded no species with the above characteristics. References: Hajdu & Ruetzler (1998). Similar species: Spirastrella coccinea Pione lampa