Plectostoma wallacei kudikense Lee, Nasir, Marzuki, Vermeulen & Khalik, 2023

Lee, Jie Ying, Nasir, Nurul Syafiqah, Marzuki, Mohammad Effendi, Vermeulen, Jaap J. & Khalik, Mohd Zacaery, 2024, The land snail fauna of Batu Kudik, isolated limestone outcrop near Simunjan, Sarawak, Malaysian Borneo (Mollusca, Gastropoda), Biodiversity Data Journal 12, pp. 115556-115556 : 115556

Plectostoma wallacei kudikense Lee, Nasir, Marzuki, Vermeulen & Khalik, 2023 n.

Materials

Type status: Holotype. Occurrence: catalogNumber: MZU.MOL.21.17 ; individualCount: 1; occurrenceID: 23E34535-FC8A-593B-942E-A4366A7F872C; Taxon: family: Diplommatinidae; genus: Plectostoma; scientificNameAuthorship: Lee, Nasir, Marzuki, Vermeulen & Khalik, 2023; Location: country: Malaysia, Sarawak; stateProvince: Samarahan; locality: Batu Kudik, small isolated limestone outcrop near Sungai Simunjan Kiri, approx. 14 miles SE Simunjan Type status: Paratype. Occurrence: catalogNumber: MZU.MOL.22.05 ; individualCount: 18; occurrenceID: 87105945-FEFE-53DE-A2C7-BDF2C6134ED9; Taxon: family: Diplommatinidae; genus: Plectostoma; scientificNameAuthorship: Lee, Nasir, Marzuki, Vermeulen & Khalik, 2023; Location: country: Malaysia , Sarawak ; stateProvince: Samarahan; locality: Batu Kudik, small isolated limestone outcrop near Sungai Simunjan Kiri, approx. 14 miles SE Simunjan Type status: Paratype. Occurrence: catalogNumber: ME 13360 ; individualCount: 13; occurrenceID: 97B4820E-0338-5337-83C4-050FE8F15112; Taxon: family: Diplommatinidae; genus: Plectostoma; scientificNameAuthorship: Lee, Nasir, Marzuki, Vermeulen & Khalik, 2023; Location: country: Malaysia , Sarawak ; stateProvince: Samarahan; locality: Batu Kudik, small isolated limestone outcrop near Sungai Simunjan Kiri, approx. 14 miles SE Simunjan Type status: Paratype. Occurrence: catalogNumber: ME 13895 ; individualCount: 23; occurrenceID: 1942E36B-DD50-5CB5-817F-E4C206B5B5C1; Taxon: family: Diplommatinidae; genus: Plectostoma; scientificNameAuthorship: Lee, Nasir, Marzuki, Vermeulen & Khalik, 2023; Location: country: Malaysia , Sarawak ; stateProvince: Samarahan; locality: Batu Kudik, small isolated limestone outcrop near Sungai Simunjan Kiri, approx. 14 miles SE Simunjan Type status: Other material. Occurrence: catalogNumber: MZU.MOL.21.20 ; individualCount: 1773; occurrenceID: EA7B72FA-229B-5865-ADCB-C420F3C288B7; Taxon: family: Diplommatinidae; genus: Plectostoma; scientificNameAuthorship: Lee, Nasir, Marzuki, Vermeulen & Khalik, 2023; Location: country: Malaysia , Sarawak ; stateProvince: Samarahan; locality: Batu Kudik, small isolated limestone outcrop near Sungai Simunjan Kiri, approx. 14 miles SE Simunjan

Description

Shell: spire conical with slightly convex sides. Apex is not or slightly oblique. Whorls 6 ½, convex; last whorl rounded or slightly angular at the periphery. Tuba free from the spire, abruptly narrowed towards the constriction, rounded below. Teleoconch: radial ribs on the spire are rather closely spaced (6 ribs/0.5 mm on penultimate whorl), slightly sinuous, often with a shallowly concave projection halfway, abrading to a not or slightly sinuous scar; those on the tuba widely spaced (6-12 ribs/0.5 mm half-way), not or hardly sinuous below (Fig. 3). Spiral striation present, distinct. Aperture: hardly tilted with regard to the coiling axis, circular to elliptic peristome simple or inconspicuous double, distant from the spire; outer peristome hardly spreading beyond the inner; inner peristome not protruding from the outer, widely spreading. Umbilicus: open, narrow, deep, 0.14-0.17 mm across. Dimensions: spire height 2.39-2.63 mm; spire width 1.49-1.64 mm, shell width (including tuba) 2.49-2.99 mm; aperture height 1.19-1.37 mm and aperture width 1.05-1.29 mm. Holotype dimensions: spire height 2.55 mm; spire width 1.57 mm, shell width (including tuba) 2.89 mm; aperture height 1.37 mm and aperture width 1.29 mm.

Diagnosis

Plectostoma wallacei kudikense (Figs 4, 5), is different from the type subspecies together with other two known subspecies by having a shell with tuba free from the spire, simple or inconspicuous double peristome and constriction with a transverse palatalis, an oblique palatalis and a knob-shaped parietalis without longitudinal palatalis. Interestingly, the oblique palatalis is absent in most Bornean diplommatinids species and observed only in Plectostoma wallacei kudikense and Moussonia isseli ( Godwin-Austen 1889).

Etymology

The specific epithet Plectostoma kudikense is in reference to the type locality, Batu Kudik.

Distribution

Known to be only endemic to Batu Kudik.

Ecology

Living snails were observed on the wet limestone wall surfaces covered with mosses and lichens inside the collapsed cave. The representative is shown in Fig. 6 .

Figures

Figure 6. Apertural, posterial, umbilical and apical views of Plectostoma wallacei kudikense subsp. nov. Holotype (MZU. MOL. 21.17). Scale = 1 mm.