Clio orthotheca (Tesch, 1948)
This is an uncoiled shelled, relatively long pyramidally shaped, pelagic snail, up to 0.8 cm long. The shell is transparent, narrow triangular in shape and oval in cross-section. Growth lines are not prominent, the lateral sides are rounded in cross section. It lives in the deep waters of all oceans (Clio orthotheca).
Shell straight without sculpture, and growth striae are absent. The lateral ribs are straight in the anterior third part; posteriorly they become concave and further on convex to the embryonic shell. The embryonic shell is oval but not pointed and separated by a distinct constriction. Longitudinal ribs on the ventral and dorsal sides are lacking. In profile the shell has a very faint curvature ventrally. The lateral ribs are only developed in the anterior 3/4 part of the shell. The height of the ventral and dorsal sides near the shell aperture are about equal. The animal most resembles Clio polita. The fins are bilobate, the posterior footlobe is well developed and curls, like a hood over the contracted fins. The whole ventral side of the posterior footlobe has unicellular glands, crowded together along the anterior margin. The lips only slightly protrude. The area surrounding the mouth is pigmented. The left mantle corner has a balancer. The zones of the pallial gland curve around the right side of the body, reaching the dorsal side.
The holotype was 8 mm long and 4 mm in width.
A special description is not available.
The species is a protandric hermaphrodite.
The species is phytophagous and epipelagic.
This species is only recorded from its type locality in the N-Indian Ocean, see the Clio orthotheca map.
Euclio orthotheca Tesch, 1948: 21, fig. 17, pl. 2, fig. 4.
Lectotype: ZMUC shell damaged. Paralectotypes: ZMUC 3 dried out specimens.
Type locality: 1°53'N 96°07'E. Coll.: CDAE stat. 3909.