| Diagnosis |
Maximum total length: 35 cm, commonly 22 cm. Mean live weight: 300 g up to 1000 g (Ref. 122);1500 g (Ref. 418). Body-wall thickness: 0.6 cm. Body: oval, arched dorsally (bivium) and flattened ventrally (trivium). Bivium with characteristics wrinkles, covered by sediment when the animal is coming out of the bottom. Bivium with small papillae within black dots, and black podia ending in a disc of around 0.022 cm diameter; podia on trivium arranged irregularly, their calcareous disc around 0.035 cm in diameter. Mouth: ventral, surrounded by a collar of papillae and 20 grey, short and stout tentacles. Anus terminal, surrounded by a circle of 5 groups of radial papillae. Calcareous ring with a large medioventral radial piece. Cuvierian tubules absent. Color: highly variable; bivium whitish to dark brown, occasionally with dark transverse markings; trivium lighter, generally whitish. Spicules: very numerous; ventral tegument with tables and buttons, the tables having a moderately small disc, perforated by a varying number of holes of variable size, the spire with 4 pillars and a cross-like bridge, ending in a spiny crown with a hole in the middle; knobby buttons generally have 6 holes, occasionally more; small rods and denticulate plates also present; tables and buttons in dorsal tegument: tables with a nodose disc, much larger than in ventral tegument; buttons variable, larger, and more perforated than those in ventral tegument; ventral and dorsal podia with long and large spinose rods; tentacles with long spiny rods, small smooth rods, and large denticulate plates (Ref. 122). |
