Type material: Holotype: Lord Howe Rise, W of New Caledonia, KANADEEP 1, Stn CP5000, 23°57 S, 161°47 E, 985– 1,050 m, MNHN-IM-2013-65645 (male?). Eight paratypes: same locality as holotype; MNHN-IM-2013-65642 (female?), MNHN-IM-2013-65643 (female), MNHN-IM-2013-65644 (female?), MNHN-IM-2013-65646 (male), MNHN-IM-2013-65647 (male), MNHN-IM-2013-65865 (female), MNHN-IM-2013-65883 (female?) and MNHN-IM-2013-65909 (male?).

Other material examined: MNHN-IM-2007-37029, MNHN-IM-2013-48364, MNHN-IM-2013-48706, MNHN-IM-2013-48842, MNHN-IM-2013-48852, MNHN-IM-2013-65868, MNHN-IM-2013-65869, MNHN-IM-2013-65870, MNHN-IM-2013-65871 and MNHN-IM-2013-65907.

Etymology: From the general area of the type locality, New Caledonia.

ZooBank registration: urn:lsid:zoobank.org:act: 01FE7631-F5E1-42D6-8B09-8C3DA1BB7627.

COI-based diagnosis: Six diagnostic (autapomorphic) positions in alignment: 112(C), 121(G), 364(G), 451(G), 454(G) and 466(G).

Shell (data for holotype shown within parentheses): Size medium to large for genus: length 7.5–17.5 (9.5) mm, width 5.6–10 (7) mm, height 2.32–7.28 (3.04) mm; thin, ellipsoidal, ovoidal or rounded and depressed; white surface with a smooth yellowish periostracum; anterior margin rounded or very slightly angled; protoconch of 1–1.2 (1) whorls, diameter of nucleus 0.1–0.2 (0.2) mm; teleoconch smooth except for distinct commarginal growth ridges; apertural margin thin, interior glossy white; lamella wide, width 0.8–1.64 (1.28) mm.

Soft parts (ethanol preserved): Head, cephalic tentacles, mantle and foot whitish; pseudoproboscis whitish, sometimes with grey speckles along the dorsal margins.

Radula: Taenioglossate, 2-1-R-1-2; marginal teeth sickle shaped; lateral teeth triangular, outer and inner edges with few denticles; rachidian tooth triangular, denticulated on both edges.

Host: No direct records. One Hyalorisia specimen (MNHN-IM-2007-37029) was found at the same sampling station as a specimen of P. investigatoris (MNHN-IM-2007-37028); note the consecutive registration numbers.

Distribution: So far known only from New Caledonia, at depths of 330–1,060 m.

Remarks: Grey speckles were observed along the dorsal margins of the pseudoproboscis of 5 of the 19 specimens examined. So far, this is the only species of this genus showing this feature.