Labidodemas

Selenka, 1867

3 species

Twenty small tentacles terminally placed, anus subterminal. Feet few, in single to double rows along the radii, rarely spreading out into the interambulacrum. Ventral feet are cylindrical, dorsally, more papilliform. Calcareous ring delicate with very long ribbon-like interradialia. Spicules few scattered tables, stout or delicate in type species a few buttons present, deformed or incomplete suggesting clumsy C-shaped bodies. (Deichmann, 1958)

Tentacles 20; pedicels and papillae generally confined to the ambulacral areas; no apparent anal teeth or papillae; body wall soft or leathery; fairly thick about 1.5 (1-2) mm; body cylindrical or vermiform, size moderate up to 150 mm; calcareous ring ribbon-like radial and interradial plates shorter than broad; spicules usually few, tables scattered, variously developed, either with disc reduced and spire low, ending in a ring of spines, or else disc well developed and spinous with spire of moderate height and usually also very spinose, buttons when present smooth, irregular, often incomplete or deformed, suggesting clumsy C-shaped bodies, minute rods sometimes present. (Rowe, 1969)

Size medium to moderate (100-200mm long); body has two distinct morphotypes: vermiform or more cylindrical; ventral tube feet mainly in am,bulacral areas, in one to four rows (sometimes also spread into the interambulacral areas); dorsal papillae and tube feet in ambulacral and often also into interambulacral areas, or absent altogether; anal papillae present or absent. Species fugitive to fosssorial, with thin body wall and 20m tentacles. Tentacle ampullae short (1/12 to 1/100 of body length). Calcareous ring with massive radial pieces and narrow ribbon-like interradial pieces. Body wall ossicles consist of variously developed tables, either with disc reduced and spire low, ending in a cluster of firm, often clavate, spines frequently longer than radius of table disc, or with disc well developed and with low to moderate spire ending in a cluster of firm spines or a wide, centrally perforated crown; buttons (when present), usually with rim smooth ro slightly knobbed, some buttons spiny, often irregular and incompletely formed; in most cases minute, occasionally perforate, branching or curved rods also present. Tube feet ossicles similar to those of body wall, with in addition rounded perforated plates. Tentacles always with smooth to slightly spiny roods. Longitudinal, transverse and cloacal retractor muscles devoid of ossicles. Curierian tubules present or absent. (Massin et al., 2004)