TYPE MATERIAL. The unique type specimen was described by OKUTANI & HABE (1981: 197-198) as having about 17 teleoconch whorls and a smooth, darkish brown, "mamillar" protoconch with 1.5 whorls. Dimensions were given as "Height 51.7 mm, breadth 21.1 mm. II B= 2.45, diameter of operculum 7.1 mm". The holotype specimen was in the private collection of S. Hayashi, the original collector. After his death, the collection was bought by a private collector in. The specimen was not available on loan for the present study, but Prof. OKUTANI kindly arranged for a color photograph of the specimen in its current condition ("The protoconch was lost and the apertural lip is a little chipped"; T. OKUTANI.).
TYPE LOCALITY. — "Southwest of Shionomisaki. Kii Peninsula, about 450 m deep". Pacific coast of Japan.
Protoconch (missing on all but one specimen from BIOCAL: stn DW 51; the following interpretation based on this only partly preserved specimen): smooth; globular; strongly hypertrophic, embryonic whorl not exposed, part of suture exposed; estimated at 135° to teleoconch axis; number of whorls not ascertained, but more than 11,2; approximately 500 µm in maximum diameter; with no distinct peritreme. Glassy white, with protoconch suture tan.
Teleoconch: tall cone-shaped, with concave whorl surfaces; very solid and large for family, up to ca. 40 mm at 19 whorls; spire angle 26-27°. Pattern of regular spiral and weaker axial ribs, intersecting at slightly oblique angles to form strong nodules Spacing of the axials initially very regular, with ca. 26 on fourth whorl, increasing to far over 100 densely-spaced lines on body whorl of large specimens. First whorl bulging, with 3 spiral ribs (middle one weakest, lowermost strongest); beginning with second whorl, regular pattern of 4 major spiral ribs; larger specimens with additional fine threads flanking middle ribs. Upper point of whorl attachment at a recessed, fifth spiral rib. partly covering it. On body whorl, this rib. and one of almost equal strength immediately below it. forming double keel at outer base. Basal area with 20-30 relatively regular spiral threads (sometimes alternating in strength). Umbilicus not open. Coloration: light tan, with areas between spiral ribs with reddish tan.
Animal: unknown. Operculum described as "horny, small for the apertural area, multispiral with partially raised spires" (OKUTANI & MAUI. 1981: 198).