Otukaia kiheiziebisu

Drawing of the apex of the shell of Otukaia kiheiziebisu.

The shell is large, conical, thin, semitransparent, pale cinnamon pink in colour with pearly lustre. The shell has 8.5 whorls. One and a half coils of nuclear portion of whorls are rounded in outline, smooth, polished on the surface. Subsequent whorls are sculptured with four strong, beaded spiral keels and very fine lines, which are only visible under a magnifying lens, and with fine oblique lines of growth. The uppermost spiral keel is situated on the subsutural area. The second and the third spiral keels are dividing the surface of whorl into three parts with unequal interval; the uppermost part the broadest, having angle of about 120° to the middle one, weakly sculptured with a thread and many exceedingly fine spiral lines near the body whorl. The lowest one is the narrowest of them all. The lowest spiral keel is concealed with succeeding whorl. The number of beads on the upper most spiral keel is ca 165-177 on the last whorl, ca 130 on penultimate whorl, ca 80 on the sixth whorl, ca 50 on the fifth whorl, ca 42 on the fourth whorl, ca 28 on the third whorl and ca 19 on the second whorl.[1]

The base is sculptured with about 40 spiral threads. The inner surface is smooth, pearly lustrous, ornamented with four spiral dull grooves which correspond to the outer keels respectively. Callus is extending over the umbilicus so as to occlude it completely, giving a shape of oblique columellar end.[1]

The height of the shell is 30 mm. The width of the shell is 33 mm.[1]

The operculum is small, round, horny, thin, translucent, marked with a fine spiral line which coils about 13 in number. The diameter of the operculum is about 13 mm.[1]

Otukaia kiheiziebisu is very similar to Calliostoma kounjiana Yokoyama in general outline, and in sculpture on the surface, but it differs from Calliostoma kounjiana in having the spirally sculptured base and the beaded spiral keels, while Calliostoma kounjiana is quite smooth both on spiral keel and the base.[1] Any other species reported from the northern Pacific has much thicker shell and more complicated sculptures than Otukaia kiheiziebisu.[1]

The type locality is Kasimanada 600 m in depth, off the east coast of Ibaraki Prefecture, Japan.[1]

This article incorporates copyright-free text from the reference.[1]

• Hasegawa K. (2009) Upper bathyal gastropods of the Pacific coast of northern Honshu, Japan, chiefly collected by R/V Wakataka-maru. In: T. Fujita (ed.), Deep-sea fauna and pollutants off Pacific coast of northern Japan. National Museum of Nature and Science Monographs 39: 225-383.

Wikimedia Commons has media related to Otukaia kiheiziebisu.

• photo of the type specimen (holotype) in the University Museum, The University of Tokyo.
• http://clade.ansp.org/obis/search.php/71835
• "Calliostoma (Otukaia) kiheiziebisu". Gastropods.com. Retrieved 16 January 2019.