1973  Rhiphaeocyclus Kuzina: 23.
     1980  Rhiphaeocyclus.-Kuzina: 68.

Type species: Rhiphaeocyclus mutabilis Kuzina,1973,p.23 [OD].

A:   Conch form at early growth stages globular, at maturity discoidal; involute, umbilicus very narrow, later closed.
C:   Distinct ribs at immature stages, smooth at maturity.
G:   Suture like Pericyclus, but first lateral saddle broadly rounded, and lateral lobes wider.

[KUZINA 1980, p.68: Conch pachycone in young individuals, subdiscoidal in adults.  Whorls completely involute,
with a rounded, not wide ventral side.  Umbilicus thin in early stages, closed later.  Sculpture represented by
distinct radial ribs in youth; adult shells completely smooth. Ventral lobe very thin, with slightly convex sides, visibly
aspiring to each other at the top.  Medial saddle very low.  First outer saddle asymmetric, rounded at the
top.  Lateral lobe equal to ventral in depth.]