Holothuria (Mertensiothuria)

Deichmann, 1958

9 species

Large smooth skinned forms with large tentacles, terminal or subventral, with cylindrical ventral tube feet and small papillae on the dorsum. Cuvierian organs present. Outer layer of tables poorly developed, at least in adult, with disc often reduced to plate with 4 central holes and in addition often smaller marginal ones; spire low, with few teeth on top, often partly resorbed. Inner layer either buttons, mostly irregular, incomplete often twisted, or in one species, reduced to rods with lateral lobes only rarely developing into complete buttons. (Deichmann, 1958)

Tentacles 18-20; pedicels crowded, or in smaller individuals (?juveniles) arranged in three distinct rows ventrally, papillae small irregularly arranged dorsally, anal papillae or collar of papillae around the base of the tentacles not apparent; body wall variable, soft, ranging from thin to fairly thick, usually about 2-3 (1-4) mm; body almost cylindrical but with a more or less flattened ventral sole; size moderate to large, up to 250 mm; calcareous ring stout with radial plates twice as long as interradials; spicules consisting of not strongly developed tables with the rim of the disc usually spinose and the spire low, ending in a ring of cluster of spines, the tables occasionally degenerate or incomplete, buttons irregular, usually with three pairs of holes, sometimes incomplete. (Rowe, 1969)