Leptoconchus inpileus sp. nov.

(Figs. 3, 9–11)

Etymology. The specific epithet reflects that the species has been found exclusively in corals of Halomitra pileus. For the purposes of nomenclature, it is herewith declared (under ICZN 1999 Article 26) as not to be treated as a Greek, Latin or latinized word; thus, the spelling presented here is to remain unchanged.

Type material. Holotype female (RMNH 90078), found in the mushroom coral Halomitra pileus; Indonesia, SW Sulawesi, Spermonde Archipelago, W Kapodasang Reef, 05°05′35″S 119°15′20″E.

Paratypes. Indonesia. SW Sulawesi, Spermonde Archipelago: type locality (RMNH 102554 /e found with holotype, 90 077/1sn: f+e, 900 79*/2 sn: m&f+e); W Kudingareng Keke Island, 05°06′09″S 119°17′09″E (RMNH 90088 /1sn: f+e); W Badi Island, 05°58′05″S 119°16′54″E (RMNH 90041 /1sn: m); W Bone Tambung Island, 05°02′05″S 119°16′16″E (RMNH 90116 /1sn: f, 90118/2sn: m&f+e).

Central Sulawesi, Tomini Bay, Togian Islands: Walea Lighthouse, 00°25′19″S 122°26′08″E (RMNH 102555 /1sn: m, 1sh: m); Barrier Reef, N Batudaka Island, 00°25′20″S 121°40′54″E (RMNH 102556 */1sn: f).

NE Kalimantan: Berau Islands (RMNH 102557/2sn: m&f+e, 102558/2sn: m&f).

Bali. Nusa Penida, 08°40′28″S 115°30′50″E (RMNH 102559 /1sh: m).

Maldives. Ari Atoll, Vilamendhoo Island (RMNH 102749*/1sn: f).

Diagnosis. Among the Leptoconchus species with reduced and variable morphological characters and associated with fungiid corals, L. inpileus sp. nov. is differentiated by a unique combination of nucleotides in the Cytochrome Oxidase I barcoding sequence (GB: EU215888–EU215890, EU215840–EU215842), as indicated by underlined letters in Fig. 48.

Shell. Holotype female (Figs. 9, 10) H 12.1 mm, W 18.5 mm; columellar callus covering most of surface of last whorl; lower half of outer lip with obtuse angle at shell base. H and W of largest female shell 21.6 mm and 22.6 mm, respectively, versus 12.3 mm and 10.8 mm for largest male. Male shell (Fig. 11) found with holotype H 8.5 mm, W 7.3 mm. Apical part of female shells not or hardly protruding above straight uppermost part of apertural edge (Fig. 9), apex of male shell in line with apertural edge or slightly lower (Fig. 11).

Habitat. The snails and their egg capsules were found at 8–18 m depth, exclusively with the mushroom coral species Halomitra pileus (Linnaeus, 1758). The siphon pores are located on the upper side of the coral discs.

Distribution. The species in known from the Maldives off Vilamendhoo Island, and from Indonesia off Kalimantan, Sulawesi and Bali. Massin”s (1992) OTU5 from NE Papua New Guinea probably represents the same species.