Biodiversity Data Journal :
Taxonomy & Inventories
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Corresponding author: Jie Ying Lee (winglee99@hotmail.com), Mohd Zacaery Khalik (kmzacaery@unimas.my)
Academic editor: Ivailo Dedov
Received: 09 Nov 2023 | Accepted: 02 Jan 2024 | Published: 16 Feb 2024
© 2024 Jie Ying Lee, Nurul Syafiqah Nasir, Mohammad Effendi Marzuki, Jaap J. Vermeulen, Mohd Zacaery Khalik
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Lee JY, Nasir NS, Marzuki ME, Vermeulen JJ, Khalik MZ (2024) The land snail fauna of Batu Kudik, isolated limestone outcrop near Simunjan, Sarawak, Malaysian Borneo (Mollusca, Gastropoda). Biodiversity Data Journal 12: e115556. https://doi.org/10.3897/BDJ.12.e115556
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The present study provides a checklist of land snails collected from Batu Kudik, a small and isolated limestone outcrop in Simunjan, Sarawak. A total of 24 species of land snails, representing 18 genera and 14 families were recorded, including one newly-described subspecies. The most species-rich of the families in Batu Kudik are Diplommatinidae (17%) and Chronidae (17%) with four recorded species from each of the families. Based on our analysis, Plectostoma wallacei kudikense subsp. nov., Opisthostoma javanica and Georissa pyrrhoderma were identified as the most abundant land snails at this isolated outcrop, whereas Diplommatina onyx and Everettia minuta were recorded as the least abundant. All of the land snails at Batu Kudik were exclusively found sheltered between limestone boulders, underscoring the critical role of this outcrop as their refuge for survival. Consequently, conserving this biodiversity-rich limestone area becomes paramount to prevent the local extinction of these land snail species and possibly other organisms that depend on the unique attributes of the limestone for their survival. We also provide detailed descriptions of Plectostoma wallacei kudikense, a new subspecies of the genus Plectostoma which is endemic to Batu Kudik.
A description of a new subspecies Plectostoma wallacei kudikense subsp. nov.
land snails, limestone, Sarawak, species abundance
Karst areas (areas on limestone bedrock) of Borneo are well-known for their rich and varied biodiversity (
Batu Kudik (
Batu Kudik is of interest because it is approximately 49 km distant from the nearest limestone outcrop, Gunung Silabur and such spatial isolation is a driver of speciation amongst limestone-bound fauna. Additionally, Batu Kudik lies in between the limestone ranges south of Kuching (to the West) and Bukit Sarang (to the East) (see Fig.
Limestone outcrops in the State of Sarawak, Malaysian Borneo. The red polygon represents the individual limestone outcrops, while the blue polygons around the limestone outcrop are background to emphasise outcrops that are too small to be seen on the map. The map is adapted from
Therefore, this study presents the first checklist of the faunistic composition of land snails at Batu Kudik. Through this study, we elucidated the species richness and species abundance of the surrounding area. In addition, we describe a new subspecies namely, Plectostoma wallacei kudikense.
Two separate surveys were conducted in October 2021 and April 2022 at Batu Kudik. The surveys were conducted around the limestone outcrops by a team of four individuals, with each survey taking a duration of at least four hours. Batu Kudik limestone outcrop is surrounded by an oil-palm plantation. During the surveys, live and empty shells were searched and collected, which consisted of sifting through leaf litter, scanning rock and wood surfaces and the surrounding karst vegetation. Top soils and leaf litters were collected to extract snails and empty shells via floatation methods. Then, shells were extracted from soil samples by manually picking up the shells and identifying them under a stereomicroscope. All specimens were identified to species level and the collected materials were deposited at Universiti Malaysia Sarawak (MZU.MOL) and the private collection (ME) of the third author. The identification of the species was based on the original description or a more recent publication of the respective species. The shell size classification were based on
Then, representatives of each of the species were photographed using a modified digital camera. For the setup and photoshoot, Capture One 15.0.0 was used for stack imaging. After that, the images were uploaded to Helicon 8.2.0 to create a composite image of the representative shell. The final images were scaled and cropped by using Adobe Photoshop 24.1 before importing into GIMP 2.10.32 to remove the background, sharpened and the images arranged onto a plate. The shell surfaces of representative paratype of Plectostoma wallacei kudikense were coated with platinum for detailed examination in scanning electron microscope (SEM). For the analysis, species abundance was computed using RStudio (
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.
Plectostoma wallacei kudikense (Figs
Plectostoma wallacei kudikense subsp. nov. Paratype (ME 13360). Scanning Electron Microscope images showing detailed characters of the shell.
Plectostoma wallacei kudikense subsp. nov. Paratype (ME 13360). Scanning Electron Microscope images showing detailed characters of the shell.
The specific epithet kudikense is in reference to the type locality, Batu Kudik.
Known to be only endemic to Batu Kudik.
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.
Sarawak: Samarahan and Kuching Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching Division. Distribution elsewhere: Indonesia: Kalimantan, Western Region (
Only dry shells were found during the surveys. The representative is shown in Fig.
Widely distributed in Sarawak, Sabah: Sapulut and lower Kinabatangan. Distribution elsewhere: Indonesia: Kalimantan, Sumatra, Java and Bali (
Living snails were observed on the wet limestone wall surfaces covered with mosses and lichens. The representative is shown in Fig.
Sarawak: Kuching, Serian and Miri Divisions (
Living snails were observed amongst the leaf litter and plant debris at the base of the limestone cliff. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan and Miri Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Samarahan Division. Distribution elsewhere: Indonesia: Kalimantan, Java, Madura and Celebes (
Living snails were observed amongst the leaf litter and plant debris inside the collapsed cave. Bornean Opisthostoma javanica Benthem-Jutting, 1932 has constriction with transverse palatalis together with infracolumellaris.
Sarawak: Kuching, Serian and Samarahan Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Serian and Samarahan Divisions (
Living snails were observed on the wet limestone wall surfaces covered with mosses and lichens. This marked the second locality record of this species after the type locality. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan, Mukah and Miri Divisions (
Widespread throughout Borneo. Living snails were observed amongst the leaf litter and plant debris near the cliff in a lowland limestone forest. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan, Sibu and Miri Divisions (
An introduced species. Widespread throughout Borneo. Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Serian and Samarahan Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan and Miri Divisions (
Living snails were observed amongst the leaf-litter and plant debris at the base of the limestone hill cliff. The representative is shown in Fig.
Sarawak: Kuching and Samarahan Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan and Miri Divisions (
Living snails were observed within the arboreal area, on leaves of palms or trees at the base of the limestone cliff. The representative is shown in Fig.
Sarawak: Kuching, Samarahan and Miri Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan and Miri Divisions (
Living snails were observed within the arboreal area, on leaves of palms or trees at the base of the limestone cliff. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan and Miri Divisions (
Living snails were observed amongst the leaf litter and plant debris near the limestone cliff. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan and Miri Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Samarahan Division (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Serian and Samarahan Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan, Sibu, Mukah, Kapit and Miri Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Serian, Samarahan, Kapit and Miri Divisions (
Only dry shells were found during the surveys. The representative is shown in Fig.
Sarawak: Kuching, Samarahan, Bintulu, Miri and Limbang Divisions (
Widely distributed. Only dry shells were found during the surveys. The representative is shown in Fig.
A total of 24 species of land snails, representing 18 genera and 14 families were recorded (see Table
The number of individuals and the relative abundance of land snails of Batu Kudik.
Family/ Genus | Number of Individuals | Relative Species Abundance (100%) |
Achatinidae | ||
Allopeas gracile | 46 | 0.4887 |
Allopeas clavulinum | 31 | 0.3293 |
Alycaeidae | ||
Stomacosmethis jagori | 186 | 1.9760 |
Assimineidae | ||
Acmella cyrtoglyphe | 3 | 0.0319 |
Ariophantidae | ||
Hemiplecta densa | 2 | 0.0212 |
Macrochlamys infans | 8 | 0.0850 |
Microcystina paripari | 7 | 0.0744 |
Camaenidae | ||
Landouria winteriana | 13 | 0.1381 |
Charopidae | ||
Philalanka kusana | 6 | 0.0637 |
Cyclophoridae | ||
Japonia bellula | 31 | 0.3293 |
Chronidae | ||
Kaliella scandens | 15 | 0.1594 |
Kaliella microconus | 15 | 0.1594 |
Kaliella calculosa | 5 | 0.0531 |
Kaliella punctata | 3 | 0.0319 |
Diplommatinidae | ||
Diplommatina concinna | 552 | 5.8642 |
Diplommatina onyx | 1 | 0.0106 |
Opisthostoma javanica | 3522 | 37.4613 |
Plectostoma wallacei kudikense subsp. nov. | 1828 | 19.4200 |
Dyakiidae | ||
Everettia minuta | 1 | 0.0106 |
Helicarionidae | ||
Helicarion dyakanum | 8 | 0.0850 |
Hydrocenidae | ||
Georissa hungerfordi | 44 | 0.0425 |
Georissa pyrrhoderma | 3070 | 32.6145 |
Trochomorphidae | ||
Videna bicolor | 4 | 0.0425 |
Valloniidae | ||
Pupisoma dioscoricola | 12 | 0.1275 |
During our fieldwork, it was observed that the majority of the inhabitants, including the land snails, were concentrated in the gaps between limestone boulders (Fig.
The land snail fauna in Batu Kudik exhibited a lower level of endemism, with only one endemic species (4%), in comparison to the slightly larger outcrops like Bukit Sarang and the larger karst cluster in the south, which have higher endemism levels of 31.3% and 38.5% for land snails, respectively. Previous studies by
Moreover, a significant portion of the limestone hills in the south (Bau Region), falls within protected areas, indicating that many of the endemic species are safeguarded. However, Batu Kudik, situated between the south and areas with agricultural activities around the limestone karst, lack such protection. As a result, factors such as quarrying, deforestation and agricultural activities become crucial determinants that may affect level of endemism, including the land snails (
The authors would like to thank Sarawak Forestry Corporation for the permission to conduct research (Permit no.: SFC.810-4/6/1-119). The authors would like to thank the head of Semalatong Village for providing hospitality and allowing us to conduct fieldwork in the area. This research is supported by the Biodiversity Research Grant Scheme UNIMAS (UNI/I01/BRG/85910/2023). The authors extend their gratitude to the reviewers, Liew Thor-Seng, Barna Páll-Gergely and Ivailo Dedov, for their valuable and constructive comments and suggestions that significantly improved the manuscript.
Conceptualisation, M.Z.K., J.J.V., L.J.Y. and N.S.N.; Fieldwork, L.J.Y., N.S.N., M.E.M. and M.Z.K.; Laboratory work, L.J.Y., N.S.N., M.E.M. and M.Z.K.; Analysis, L.J.Y.; Data curation, L.J.Y.; Writing the manuscript L.J.Y., N.S.N., M.E.M., J.J.V. and M.Z.K; Supervision, M.Z.K.; Funding acquisition, M.Z.K.