Ancistrolepis unicum: Height 86.8 mm, Width 49 mm

Ancistrolepis unicum: Shell is moderately large in size, solid, fusiform, consists of 6.5 convex whorls, divided by a channeled sutura. The body whorl occupies of 2/3 of the sheli height, with rounded base. There are wide ground between the sutura and first keel. Spiral sculpture consists of three keels, more distinct are present on the shoulder of whorls. Also, there are spiral cords, which more distinct in the low part of the body whorl (21-16 on the body whorl). Besides, all the shell surface (except siphonal area) is covered with thin riblets (5-6 on 5 mm of the shell surface. Aperture is wide, rounded, white, occupies about 1/2 of the shell height. Inner lip is covered with thin white callus. Siphon is short, wide, slightly curved to the left. Color of shell is creamy, brownish or yellowish-white with irregular brownish spots. Periostracum is greenish-brownish, thin, dense, form short bristles.
[Egorov, 1994]

Clinopegma magnum (Dall, 1895)f. aequapaceum (=unicum) Tiba, 1981 BUCCINIDAE
-400~600m, southeast Nemuro, Hokkaido, Japan, 97.5mm., 2013/vii
Known from Hokkaido, Japan to Sakhalin Island, Clinopegma magnum f. aequapaceum is a rather rare and perhaps the most attractive form of the « Magna Whelk ». C. magnum is itself very widely distributed from Hokkaido, Japan to Aleutian Islands and is extremely variable. It may be fusiform or stout, and the number of spiral cord vary in general from a single strong subshoulder keel to more than ten; many names have been given to its various forms. Form aequapaceum represents a tall-spired variety with very strong cords; similar to C. magnum f. unicum (Pilsbry, 1905) but with more numerous and stronger cords below the sub-shoulder keel. C. m. f. unicum is often regarded as a Hokkaido to Sea of Okhotsk subspecies of C. magnum. It is a carnivorous / scavenging gastropod inhabiting sandy to muddy bottoms of rather deep water around -200~600m in depth. Typical shell length around 80mm., very large specimens may exceed 110mm.

Ancistrolepis unicum: Japan (type locality); southern part of the Okhotsk Sea, Sakhalin Island, at depth about 100-250 m. Rare.