Pupa tragulata Iredale, 1936

(Figs 15H–J)

Pupa tragulata Iredale, 1936: 331, pl. 24, fig. 23. Type locality: off Sydney, 75–85 fm depth.

Pupa strigosa sekii Habe, 1958: 117. Type locality: off Chosi, Chiba Prefecture, Japan.

Pupa sinica Lin, 1989: 169, 176, fig. 2. Type locality: East China Sea, 105 m depth.

Type material. Pupa strigosa sekii — Holotype, dry shell, 6.9 mm long (NSMT Mo.39815), illustrated by Higo et al. (2001: 137); Pupa sinica — Holotype, dry shell, 5.2 mm long (IOCAS Mo 26971).

External morphology. Live animal unknown. Shell solid, oval to elongate, widest at midlength, with convex to parallel sides, rounded to elongate anterior end (Figs 15H–J). Body whorl large, about 4/5 of total length. Spire conical, with 3–4 whorls. Suture channeled. Aperture elongate, wider anteriorly, narrowing abruptly towards posterior end, ending at 1/5 of the posterior end of first whorl. Columellar margin thickened, slightly oblique, with large, channeled anterior fold starting at anterior end of aperture; small, simple posterior fold located at aperture mid-length, separated from anterior fold by short gap. Protoconch not observed. Sculpture composed of numerous, conspicuous punctuated spiral grooves. Punctuations conspicuous, irregular, oval, situated next to each other, often fused together, within each groove. Grooves separated by gaps wider than grooves. Shell color uniformly white to pale cream.

Geographic range. West Pacific Ocean from southern Australia to China and Japan (present paper).

Remarks. Iredale (1936) described Pupa tragulata Iredale, 1936 based on a single white shell collected off Sydney at 75–85 fathoms (137–155 m depth). Beu (2004) treated this species as a synonym of Pupa affinis but Burn (2006) maintained Pupa tragulata as valid, mentioning some differences in radular morphology support its retention as a separate deep-water species.

Habe (1958) introduced Pupa strigosa sekii Habe, 1958 as a subspecies of Pupa strigosa with a brief description, and based on a single specimen collected off Chosi, Chiba Prefecture, Japan. Habe (1958) indicated the new subspecies is similar to P. strigosa proper but it is somewhat different as it lacks colored markings on the surface of the shell. Although Habe (1958) provided no illustrations of this new subspecies, the holotype was later illustrated by Higo et al. (2001: 137). Although Beu (2004) considered P. strigosa sekii a synonym of Pupa affinis, Pupa sekii is currently considered as a valid species of Pupa with a broad distribution in southeast Asia (Willan & Tagaro, 2010; Helwerda, 2015; Chaban, 2016; Nakano, 2018; Bu-on & Dumgrongrojwattana, 2020).

Lin (1989) introduced the name Pupa sinica Lin, 1989 based on two specimens collected from the Each China Sea from 17–105 m depth. Lin (1989) described this new species as having a small, fusiform, gray-white, rather solid shell, with an elevated, conical spire, and a black-brown colored periostracum. Lin (1989) argued that P. sinica resembled P. sulcata in shape but had a smaller shell with a black-brown epidermis, yellowish axial lines, and an elevated, conical spire. A photograph of the holotype (IOCAS Mo 26971) here illustrated (Fig. 15J) is consistent with the original description, but also resembles the characteristics of the holotype of P. strigosa sekii Habe, 1958 (illustrated by Higo et al., 2001: 137) and they are likely synonyms. However, due to the lack of anatomical and molecular data for the two species, this synonymy remains unverified.