Djakonov, 1950: 54 (1968: 45), 1952: 409.
Occurrence: Okhotsk Sea. 97 m.
Comments: This species was described by Djakonov (1950) as a separate species based on extremely swollen and hemispherical marginal and abactinal plates. This character is plesiomorphic to H. spinosa (and to a certain extent, H. phrygiana), which undermines the distinctiveness of this species and further lends support to its synonymy with H. spinosa.
Material examined: None.