The gastropod once assigned to Terebralia palustris (Potamididae) from the Upper Pliocene part of the Ananai Formation of Shikoku, Japan, was reassigned to the cerithiid genus Pseudovertagus and redescribed as a new species Pseudovertagus kondoi sp. nov. Scrutiny of fossil gastropods once referred to Pseudovertagus shows that the fossil record of this genus is sparse, with only Pseudovertagus aluco in the Plio–Pleistocene beds in Indonesia. Pseudovertagus kondoi sp. nov. is the second oldest species of the genus Pseudovertagus and thought to have been semi-infaunal sand-bottom dwellers in the open-sea, inner shelves. The shells exhibit characteristic pits with high frequency on the outer surface, likely caused by the co-occurring commensal hipponicid limpet, Sabia conica. Infestation with S. conica was suggested to occur more frequently on hermitted shells than on the live snails. This study provides an additional example of the Sabia-gastropod-hermit crab association from the fossil records. The shells of P. kondoi sp. nov. preserve remarkable color markings, although they are absent or much less distinct in other associated mollusks. This unusual preservation of color markings is thought to be due to the presence of a very thin shell layer that covers the pigment-bearing shell layer and prevents pigment decomposition.