Holothuria (Thymiosycia)

Pearson, 1914

15 species

Comparatively slender, spindle or bottle shaped form rarely 25 cm long, with 20 small terminal tentacles and terminal anus. Appendages not numerous, more papilliform on dorsum, often arranged in 5 bands. Inner anatomy not remarkable; usually one stone canal and one or two polian vesicles. Cuvierian organs developed. Spicules an external layer of tables with smooth edged disc and, in the adult, a low spire with varying number of teeth; in young individuals, the spire sometimes tall with several cross beams. Inner layer of smooth buttons of moderate size, usually with three pair holes. Ventral feet with large end plate or none, and supporting rods more narrow and often curved. (Deichmann, 1958, for Brandtothuria)

Tentacles 18-20; pedicels and papillae usually irregularly arranged ventrally and dorsally, respectively, or occasionally restricted to the ambulacral areas; anal papillae more or less apparent, a collar of papillae usually present around the base of the tentacles; body wall not very thick, usually 2 (1-5) mm; body rather vermiform, size small to moderate, up to 200 (rarely 250) mm long; calcareous ring stout, radial plated up to three times the length of the interradials; spicules consisting of fairly stout tables, the disc flat and squarish or irregular in outline, rarely reduced, usually with 8-10 peripheral holes, the spire of moderate height ending in a cluster of small spines, the buttons regular or irregular in outline with three or more pairs of comparatively large holes (except in H. (Thymiosycia) arenicola which has comparatively small holes) not flattened, lacking any appearance of having median longitudinal ridge, rarely buttons present with slight holes or forming hollow fenestrated spheres as in H. (Thymiosycia) aphanes. (Rowe, 1969)