The shell is small, tall patelliform with posteriorly involuted apex situated at about the center. The aperture is oval, with width being two-thirds, and height about half the length, respectively. The elongate triangular orifice is situated near the top with a very short selenizone behind. The surface is ornamented with strong radial ribs, about 35 in number including intercalated secondary riblets. They are all crossed by concentric growth lines that make the shell surface rather rough.
The internal surface of the shell is white, shining and is ornamented with radial grooves corresponding to external ribs and weak, discontinuous, concentric lines. The septum behind the orifice is well raised, halfly encircling the orifice.
The radula is rhipidoglossate, typical for the family. The central tooth is broadly based, trapezoid in shape, with overhanging top. The laterals are similar in shape, but the outer ones have peculiar flare on the shaft. The innermost marginal (outermost lateral) is extremely large, with broadly curved top that has a pointed tip and a few blunt cusps with irregular dentitions. The marginals have forked top and diminish their size outwardly.
Measurements: Holotype (NSMT Mo-69968) length 5.2 mm, width 3.5 mm, height 3.0 mm. Paratypes (NSMT Mo-69969 a-c) 4.1 x 3.1 x 2.9 mm (a). Remarks: This species is a tiny fissurellid somewhat similar to a Japanese shelf species, P. (Cranopsis) pelex A. ADAMS, 1860, but the latter has more anteriorly situated orifice and posteriorly situated apex. The northern species, P. nobilis A. ADAMS, I860 is larger than the present new species and has fewer and lower ribs.
MCLEAN (1984) stated that there are few specific differences in the central and inner lateral teeth in this genus except for the large outer lateral (innermost marginal). It is true for the above two new species of which that particular tooth exhibits slight differences, but the other radular characters are common with each other regardless of remarkably differences in shell characters.
Distribution: Not known from other than the type locality (Minami Ensei Knoll, 690 m deep).