Edenttellina limax (Kawaguti & Baba, 1959)

Location: Gakkoushita(pool mae), Etizen, Fukui, Japan
Date: 2025/07/12
Length: 5mm
Depth: 10.0m
Water temperature: 27.0℃

Description

A small bivalved sacoglossan (Juliidae). The shell reaches up to 8 mm in length, elongate-oval in side view, inflated and rather strongly convex, with a rounded posterior end and umbos at the posterior one-third of the shell length, not strongly elevated. Extremely thin and translucent, pale yellowish-green or yellowish-white, with a smooth surface marked by very fine growth lines crossed by indefinite radiating threads; the periostracum is colourless and the pearl layer shining. The left and right valves are almost equal in size, shape and convexity, combined dorsally by a faint ashy-yellow ligament under a contiguous layer of periostracum; each valve forms an elongate hinge plate below the umbo, and the two valves are articulated at the front and rear ends of the hinge by cardinal teeth and corresponding sockets. The helicoid protoconch at the apex of the left valve is small, inclined nearly horizontally, and extends over the right valve. An adductor muscle scar lies in the anterior half of each valve. Largest fully extended animal about 12 mm. The soft body is snail-shaped with auriculate rhinophores and lobiform oral tentacles; paired eyes lie close together, the eye region forming a small projection on the neck in the midline.

Distribution

Known from the Inland Sea of Seto (common) and Toyama Bay (Japan Sea, rare). Type locality: Tamano, Okayama Prefecture (Inland Sea of Seto). Feeds on the green alga Caulerpa okamurai.

Etymology

The specific epithet limax is Latin for "slug", in reference to the slug-like soft body inside the bivalve shell.

Remarks

The original generic name Tamanovalva was placed in synonymy with Edenttellina. Some workers further regard the older name Berthelinia as the priority genus, and WoRMS and other current databases tend to accept the combination Berthelinia limax.