Ypsilothuria

Perrier E, 1896

2 species

Spherical to U-shaped Dendrochirotes, always with 8 tentacles, and without the two ventral interradials. Two of the tentacles, one on each side, are much larger than the others. Calcareous deposits of body wall large plates with a more or less central spine. These plates form a real test. Those of the anterior and posterior end much imbricating, and without spire. (Heding, 1942)

Shape U-shaped to round, 8 tentacles, 2 ventral ones lacking, on each side one tentacle is larger than the rest. The calcareous ring is simple, without forked tail; the two ventral interradialia are lacking. In the skin there is a firm skin armour of large plates, which consists of several net layers, positioned roof tile fashion. They have a somewhat central positioned top construction consisting of several columns or of net layers positioned one on top of the other. On the anterior and posterior end the plates with the top construction are lacking. (Panning, 1949)

Tentacles 8-10, lateral tentacles enlarged. Body U-shaped, mouth and anus dorsal. Body invested in large (ca. 1 mm diameter) thick scales composed of many layers of calcareous material. Each scale carries a long spire at or near its center. (Pawson, 1965)

Podia in more or less distinct series along the ambulacra, not scattered irregularly. Body covered by large spinous scales, which are perforated by tube feet. The scales are thick, of several layers, with spines placed near the center. Mouth and anus dorsal. A pair of enlarged lateral tentacles. (HBF)