Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia

Junn Kitt Foon; Gopalasamy Reuben Clements; Thor-Seng Liew

doi:10.3897/zookeys.682.12999

Research Article

Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia

Junn Kitt Foon^‡, Gopalasamy Reuben Clements^§, Thor-Seng Liew^‡

‡ Universiti Malaysia Sabah, Sabah, Malaysia

§ Sunway University, Selangor, Malaysia

Corresponding author: Thor-Seng Liew ( thorsengliew@gmail.com )

Academic editor: Martin Haase

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: Foon JK, Clements GR, Liew T-S (2017) Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia. ZooKeys 682: 1-94. https://doi.org/10.3897/zookeys.682.12999

ZooBank: urn:lsid:zoobank.org:pub:0AE82225-C67E-4D90-8BBE-C30124E6C312

Abstract

Limestone hills are now gaining global conservation attention as hotspots for short-range endemic species. Levels of land snail endemism can be high at limestone hills, especially at hill clusters that are geographically isolated. In the State of Perak, Peninsular Malaysia, limestone hills have been opportunistically surveyed for land snails in the past, but the majority have yet to be surveyed. To address this knowledge gap, we systematically surveyed the terrestrial malacofauna of 12 limestone hills that, based on our opinion, are a representation of the limestone land snail assemblages within the State. Our inventory yielded high sampling completeness (>85%). We found 122 species of land snails, of which 34 species were unique to one of the surveyed hills. We identified 30 species that are potentially new to science. The number of land snail species recorded at each hill ranged between 39 and 63 species. Four of the sampled limestone hills namely, Prk 01 G. Tempurung, Prk 55 G. Pondok, Prk 47 Kanthan, and Prk 64 Bt Kepala Gajah, have high levels of species richness and unique species, representing 91% of the total species recorded in this study. We identified two clusters of limestone hills in central Perak with distinct differences in land snail species composition – a northern hill cluster on elevated granite bedrock and southern hill cluster in a low-lying valley surrounded by alluvial soils. As limestone hills continue to be quarried to meet the cement demand, the four identified limestone hills, along with other hills from the two clusters, warrant urgent conservation attention in order to maintain high species diversity within Perak’s terrestrial malacofauna.

Keywords

Biogeography, checklist, conservation, endemism, karst, Kinta River, mollusc, Perak River

Introduction

Limestone hills are popularly known as “arks of biodiversity” because they contain high levels of species endemism, especially in Peninsular Malaysia where these hills only cover 0.2 % of the total land area (Schilthuizen 2004; Clements et al. 2006; Chua et al. 2009; Liew et al. 2014).

To date, at least 445 limestone hills have been documented in Peninsular Malaysia, with the majority located in the States of Kelantan (149 hills), Pahang (124 hills) and Perak (93 hills) (Liew et al. 2016). The State of Perak has the third largest number of limestone hills, but it has the largest number of operating quarries (Liew et al. 2016). The majority of these hills can be found within the Kinta Valley, with some other hills scattered around the northern part of the Kinta Valley and Bintang Range (Figure 1). Over the past decade, the endemism of different plant and animal at the limestone hills of Perak has drawn attention from evolutionary biologists (Clements et al. 2008a), conservationists (Clements et al. 2008b) and concerned taxonomists (Kiew et al. 2014; Vermeulen and Marzuki 2014). Given the large number of limestone hills in Perak, it is not practical to spare every hill from quarrying. Thus, conservation prioritisation needs to be conducted, ideally based on the biogeographical patterns of endemic taxa such as land snails (Clements et al. 2008b).

Figure 1.

The 12 limestone hills sampled in and around the Kinta Valley of Perak, Peninsular Malaysia.

The limestone hills in Perak form an important region because that was where the foundation for land snail knowledge in Peninsular Malaysia was laid. More than 50 land snail species have been described from this State alone; these species descriptions were the outputs of three main faunistic studies by separate groups of naturalists and malacologists. The first was an expedition to central Perak by de Morgan (1885a), who described 33 new land snail species from the area. Second was the work by von Möllendorff, who published a species checklist of around 60 species and described 15 new species based on the collection by R. Hungerford at Gunung Larut (von Möllendorff 1886, 1891). Third was the survey done by E. Townsend at Gunung Pondok, where around 13 new species were described (Godwin-Austen and Nevill 1879; Crosse 1879a, 1879b). Besides these faunistic surveys in Perak, at least 20 new species were described based on taxonomic studies of particular land snail taxa or random sampling (van Benthem Jutting 1952, 1954, 1961a, 1961b; Tomlin 1938, 1939, 1941; Fulton 1901, 1902; Sykes 1903; Godwin-Austen 1909). More recent studies suggest that about one-third on the known species from Peninsular Malaysia can be found in Perak, particularly around the Kinta Valley (Davison 1991; Chan 1998a, 1998b; Clements et al. 2008b; Maassen 2001). In Perak, land snail species richness on a hill can reach as high as 53 species (Clements et al. 2008b).

Despite intensive land snail research conducted in the State of Perak, the land snail inventory is far from complete. Most of the comprehensive surveys only report the name of the species, without illustrations of the species, or with provisional working species names, such as sp. 1, sp. 2. (e.g. Davison 1991; Clements et al. 2008b). This has made it difficult to update current checklists because species identities in previous reports cannot be used to compare with recently collected specimens. Furthermore, many of these unnamed species in previous reports are probably new species yet to be described or are doubtful species that require taxonomic revision. Hence, good annotated checklists of land snails with traceable specimens and high quality illustrations are key to improve the current knowledge of land snails in Perak and Peninsular Malaysia in general.

The biogeography of organisms on limestone hills in Perak is also poorly known. In Peninsular Malaysia, land snail communities on limestone hills can generally be divided into two groups, one on the hills along the east coast and the other on the hills along the west coast, both of which are separated by Main Range in the centre of the peninsula (van Benthem Jutting 1960; Clements et al. 2008b). Within the State of Perak, Davison (1991) noticed land snails on limestone hills can be further divided into two groups, one on the hills within Kinta Valley and the other one on the hills scattered in the area north of Kinta Valley, though based on an incomplete land snail inventory (Davison 1991: 6 – 35 species from 12 hills, averaging 17 species per hill, compared to Clements et al. 2008b: 32 – 53 species from 6 hills, averaging 42 species per hill). As such, further quantitative analysis on the biogeographical patterns of land snails with more comprehensive species inventories from limestone hills that are representative of Perak’s terrestrial malacofauna can contribute to improved limestone conservation planning within the State.

Limestone hills have been recently highlighted as one of Malaysia’s vulnerable ecosystems due to surrounding forest degradation and quarrying activities (Ministry of Natural Resources and Environment Malaysia 2016). Many land snail species that are endemic to limestone hills in Peninsular Malaysia are already extinct or on the brink of extinction (http://www.iucnredlist.org/search/link/57e5b1fd-2bc5b54c). In order to prevent further species extinctions, limestone hills that are currently being quarried or intact must be urgently assessed for land snail diversity.

Here, we conduct a land snail inventory in and around the Kinta Valley of Perak to: (1) provide an annotated checklist of land snail species for the State, along with photographic images for each species; and (2) elucidate land snail diversity and biogeographical patterns across 12 limestone hills within the State. For the second objective, we specifically examined relationships between limestone hill parameters (size and isolation) and species richness and biogeographical patterns of land snails. Finally, we discuss the conservation implications of our study for limestone hills in Perak.

Methodology

Sampling design and sites

In addition to six limestone hills previously surveyed by Clements et al. (2008b), six other limestone hills were included in this study. Among the six previously sampled hills, only one (i.e. Gunung Bercham) was resampled because of the low sampling completeness reported by Clements et al. 2008b. Sampling was conducted between 16/8/2016 and 24/8/2016. Our sampling approach consisting of 12 limestone hills will (1) result in the sampling of more hills in clusters that have a larger number of limestone hills; and (2) provide wider geographical coverage of limestone hills across the Kinta Valley (Table 1; Figure 1).

Table 1.

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The geographical coordinates, size, isolation of 12 limestone hills sampled in this study in and around the Kinta Valley of Perak. The names of the limestone hills follow a standardized national code developed by Liew et al. (2016).

No.	Limestone hills	Longitude / Latitude	Size (km²)	Degree of Isolation^@	Species richness	Unique species
1	Gunung Kanthan*	4.761388, 101.1210	0.827	5	63	6
2	mykarst-025*	4.653244, 101.1539	0.122	13	40	1
3	Prk 1 G. Tempurung*	4.415082, 101.1877	8.722	6	54	9
4	Prk 23 G. Rapat^	4.552856, 101.1311	5.379	17	45	3
5	Prk 34 G. Tasek^	4.643467, 101.0998	0.114	13	45	1
6	Prk 36 Gua Datok^	4.627492, 101.1581	0.644	16	49	1
7	Prk 53 Hill KF^	4.854229, 101.1225	0.038	8	44	1
8	Prk 55 G. Pondok^	4.786687, 100.8402	0.662	1	50	5
9	Prk 64 Bt Kepala Gajah*	5.118655, 100.9727	1.075	7	45	7
10	mykarst-184 Bat Cave*	4.906175, 101.1467	0.014	6	50	0
11	mykarst-185 Batu Kebelah*	4.853657, 101.1864	0.022	4	39	0
12	Prk 42 G. Bercham #	4.644832, 101.1338	0.059	16	45	0

Land snails sampling and processing

In each of the seven limestone hills, four 2 m × 4 m plots were established (Clements et al. 2008b; Liew et al. 2008; Suppl. material 1). In each plot, a total of five litres of top soil and leaf litter were collected for extraction of micro-snails (< 5 mm) and the plot was searched for macro-snails. Upon returning to the laboratory, all macro-snails were cleaned with running water and then dried in an oven.

After that, shells were extracted from soil samples by manually picking up the shells under a stereomicroscope (Liew et al. 2008). For species identification, a complete literature of Malay Peninsular terrestrial mollusca was consulted, with emphasis on the most recent species compilation and overview by Maassen (2001). All specimens from recent sampling and previous studies (Clements et al. 2008b) were identified to morphospecies based on a combination of photographs, illustrations and description of types. Morphospecies that could not be assigned to an available name were given working morphospecies names (for example, Acmella ‘Kanthan 1’). Species reported to be present in our study sites in the literature, but not found during our sampling, were not included in our results. All specimens were catalogued in the BORNEENSISMollusca collection database and were deposited in the BORNEENSIS collection of Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah.

Data analysis

A species checklist was compiled for the 12 limestone hills and was arranged according to the classification of Maassen (2001). Under species or subspecies, four subsections were provided: (1) Reference to figures; (2) Materials examined, which includes only species sampled from this study (with the exception of some species where poor shell preservation warranted a substitute specimen from other studies for photographic purposes); (3) Distribution, which is separated into distribution within Peninsular Malaysia and distribution elsewhere; (4) Remarks, which includes brief diagnosis, comparison with conspecifics and note on new records. All species are considered native unless noted as synantropic in Remarks.

For our analysis of land snail diversity patterns, we first assessed species diversity in terms of (1) species richness – total number of species for each hill; and (2) unique species – species found only in one of the twelve limestone hills in this study. Next, we assessed whether there was a correlation between the species richness and the number of unique species for the twelve hills. We also examined relationships between species diversity and limestone hill parameters (i.e. size and degree of isolation). Depending on the normality test of data for each parameter, Spearman or Pearson correlation coefficients were used to test for correlations. Analysis was conducted using built-in function in the R statistical environment v. 3.3.1 (R Core Team 2016).

For our analysis of land snail biogeographical patterns, land snail data were tabulated into a data matrix of 122 species × 12 limestone hills that consisted of absence (0)/presence (1) data for each species on each of the twelve hills. We evaluated sampling completeness for all 12 hills and compared their species composition to determine their degree of similarity. A cluster analysis was performed to objectively assign limestone hills into clusters so that hills within each cluster are similar to one another with respect to overall land snail composition. In our analysis, a dissimilarity distance matrix was calculated using the Jaccard similarity coefficient (i.e. Jaccard index) based on the data matrix. Next, hierarchical clustering on the 12 sites based on the dissimilarity matrix was performed using the method of complete linkage. Analysis was conducted using package ‘vegan’ (Dixon 2003) and ‘iNEXT’ (Hsieh et al. 2016) in the R statistical environment v. 3.3.1 (R Core Team 2016).

Results

Diversity and biogeography of land snails

We achieved high sampling completeness (> 85 %) for all seven limestone hills sampled in our study (Suppl. material 3). The species richness and number of unique species that can be found only in a single hill is listed in Table 1. The number of land snail species recorded in each hill ranges between 39 species and 63 species. Gunung Kanthan has the highest number of species – 63 species with 6 unique species, and followed by Gunung Tempurung – 54 species with 9 unique species. The list of 34 unique species found in each limestone hills is listed in Table 2. The species richness and number of unique species of each hill were also mapped to understand land snail diversity patterns among the limestone hills in and around the Kinta Valley of Perak (Table 1)

Table 2.

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Unique species for each of 12 limestone hills (and species richness [SR]) in and around the Kinta Valley of Perak, Peninsular Malaysia.

Prk 01 G. Tempurung (SR = 54)	Prk 55 G. Pondok (SR = 50)
Glyptaulax ‘tempurung 1’	Chamalycaeus microconus (von Möllendorff, 1886)
Macrochlamys ‘tempurung 1’	Chamalycaeus oligopleuris (von Möllendorff, 1886)
Macrochlamys ‘tempurung 2’	Lagochilus ‘pondok 1’
Microcystina ‘tempurung 2’	Microcystina ‘pondok 1’
Microcystina ‘tempurung 3’	Sinoennea perakensis (Godwin-Austen & Nevill, 1879)
Opisthostoma cf. vermiculum
Opisthostoma ‘tempurung 1 detached’
Paraboysidia ‘tempurung 1’	Prk 23 G. Rapat (SR = 45)
Rahula ‘tempurung 1’	Arinia (Notharinia) micro Marzuki & Foon, 219
	Opisthostoma megalomphalum van Benthem Jutting, 1955
Prk 47 Kanthan (SR = 63)	Opisthostoma vermiculum Clements & Vermeulen, 2008
Chamalycaeus ‘Kanthan 1’
Chamalycaeus ‘kanthan 2’
Diplommatina cf. diminuta	Prk 36 Gua Datok (SR = 49)
Lagochilus townsendi Crosse, 1879a	Pupina arula perakensis von Möllendorff, 1896
Opisthostoma cf. gittenbergeri
Opisthostoma cf. subconicum
	Prk 34 G.Tasek (SR = 45)
	Arinia (Notharinia) ‘tasek 1’
Prk 64 Bt Kepala Gajah (SP = 45)	mykarst-025 (SR = 40)
Diplommatina lenggongensis Tomlin, 1941	Opisthostoma ‘mykarst-25 1’
Microcystina ‘guatokgiring 1’
Microcystina ‘guatokgiring 2’	Prk 53 Hill KF (SR = 44)
Opisthostoma castor van Benthem Jutting, 1961	Sinoennea ‘prk53 1’
Sinoennea ‘guatokgiring 1’
Sinoennea lenggongensis Tomlin, 1948	mykarst-184 Bat Cave (SP = 50)
Sinoennea tweediei Tomlin, 1941	None.
Prk 42 G. Bercham (SP = 45)	mykarst-185 Batu Kebelah (SP = 39)
None.	None.

Species richness and the number of unique species were not correlated among the 12 hills (p = 0.052, Figure 2A). There appears to be no relationship between the species richness and limestone hill size (p = 0.12) and isolation (p = 0.5) (Figure 2B, C). On the other hand, the number of unique species was strongly correlated with limestone hill size (r_s = 0.91, p = 0.0005), but not isolation (p=0.43) (Figure 2D, E).

Cluster analysis identified two clusters of limestone hills based on land snail species composition: a northern cluster and southern cluster (Figure 3). The northern cluster comprises four limestone hills: Prk 64 Bt. Kepala Gajah, Prk 55 G. Pondok, mykarst-184 Bat Cave, and mykarst-185 Batu Kebelah. The Southern cluster consists of the remaining limestone hills in the Kinta Valley (Figure 3).

Figure 2.

Relationships between limestone physical parameters and land snail species diversity of the 12 limestone hills in Perak, Malaysia. Limestone hills size indicated by relative point size in the plot. A Relationship between species richness and number of unique species B Relationship between species richness and limestone hills size (km²) C Relationship between species richness and degree of isolation of the limestone hills D Relationship between number of unique species and limestone hills size (km²) E Relationship between number of unique species and degree of isolation of the limestone hills.

Figure 3.

Cluster analysis of land snail species composition of 12 limestone hills in and around the Kinta Valley of Perak, Peninsular Malaysia. Two clusters were identified: a northern (blue dots) and southern cluster (yellow dots). Green polygons with red boundary refer to major clusters of limestone hills in Kinta Valley identified based on the 2.5 km buffer analysis (i.e. at least 2.5 km from the nearest cluster/hills). Red dots indicate limestone hills not sampled in this study.

Checklist

In total, we recorded 122 species from the 12 limestone hills sampled in and around the Kinta Valley of Perak (Suppl. material 2). This checklist consists of 23 families and 47 genera. There are 30 out of 122 species identified from this project which could not be assigned to scientific names that are currently published. Some of these unnamed species are potentially new to science but systematic taxonomic revisions need to be done as many of these groups have not been critically revised. The most diverse genera were Opisthostoma (13 species), Microcystina (10 species), and Diplommatina (9 species).

Class Gastropoda Cuvier, 1795

Clade Caenogastropoda Cox, 1960

Family Assimineidae Adams & Adams, 1856

Genus Acmella Blanford, 1869

Acmella ‘Kanthan 1’

Figure 4A

Materials examined

Prk 47 Kanthan: BOR/MOL 9079, BOR/MOL 9157.mykarst-184 Bat Cave: BOR/MOL 9781, BOR/MOL 9839, BOR/MOL 12502. Prk 64 Bt Kepala Gajah: BOR/MOL 10192. Prk 23 G. Rapat: BOR/MOL 10237. Prk 36 Gua Datok: BOR/MOL 10453. Prk 42 G. Bercham: BOR/MOL 10583, BOR/MOL 12497, BOR/MOL 12498, BOR/MOL 12503. Prk 53 Hill KF: BOR/MOL 10784. Prk 01 G. Tempurung: BOR/MOL 11397, BOR/MOL 12501.

Distribution

Known from Kinta Valley and Lenggong, Perak only.

Remarks

Very small shell. Tall spire, conical shaped shell. Radial ribs prominent, chevron-shaped with the pointed end in the opposite direction of shell growth. Acmella roepstorffiana Nevill, 1878 from Pahang differs in radial rib shape.

Figure 4.

Small shell. Radial ribs prominent, at equidistant. Spiral sculpture fine, indistinct. Peristome expanded and reflected. Differs from other Perak congeners by its more globose whorls.

Figure 5.

A Alycaeus thieroti de Morgan, 1885a BOR/MOL 10258. Perak, Ipoh, Gunung Rapat Plot C7 B Chamalycaeus diplochilus (von Möllendorff, 1886) BOR/MOL 10098. Perak, Ipoh, Gua Tok Giring C Chamalycaeus ‘Kanthan 1’ BOR/MOL 9127. Perak, Ipoh, Gunung Kanthan Plot 2 D Chamalycaeus ‘kanthan 2’ BOR/MOL 9160. Perak, Ipoh, Gunung Kanthan Plot 4 E Chamalycaeus microconus (von Möllendorff, 1886) BOR/MOL 11485. Perak, Ipoh, Gunung Pondok F Chamalycaeus microdiscus (von Möllendorff, 1886) BOR/MOL 10206. Perak, Ipoh, Gunung Rapat.

A Chamalycaeus oligopleuris (von Möllendorff, 1886) BOR/MOL 11616. Perak, Ipoh, Gunung Pondok B Chamalycaeus parvulus (von Möllendorff, 1886) BOR/MOL 11615. Perak, Ipoh, Gunung Pondok C Crossopoma albersi (Pfeiffer, 1847) BOR/MOL 9134. Perak, Ipoh, Gunung Kanthan Plot 2 D Cyclophorus malayanus (Benson, 1852a) BOR/MOL 9578. Perak, Ipoh, Batu Kebelah Plot 3 E Cyclophorus perdix perdix (Broderip & Sowerby, 1829) BOR/MOL 8274. Perak, Ipoh, Iron hill summit F Cyclophorus semisulcatus (Sowerby, 1843) BOR/MOL 9577. Perak, Ipoh, Batu Kebelah Plot 3.

Chamalycaeus parvulus (von Möllendorff, 1886)

Figure 6B

Materials examined

mykarst-025: BOR/MOL 9431, BOR/MOL 9514. Prk 42 G. Bercham: BOR/MOL 9467. Prk 36 Gua Datok: BOR/MOL 10506. Prk 53 Hill KF: BOR/MOL 10781. Prk 55 G. Pondok: BOR/MOL 11615, BOR/MOL 11587.

Distribution

Known from Bukit Pondok (Maassen 2001) and Kinta Valley, Perak only.

Remarks

Shell similar size to Chamalycaeus microdiscus but whorls differ in being rounder and radial ribs denser and less pronounced. New record for Kinta Valley.

Genus Crossopoma von Martens, 1891

Crossopoma albersi (Pfeiffer, 1847)

Figure 6C

Materials examined

mykarst-027: BOR/MOL 9134.

Distribution

In Peninsular Malaysia, known from Dindings (=Manjung) and Kinta Valley, Perak (Maassen 2001). Elsewhere, in Sumatra, Indonesia (van Benthem Jutting 1959).

Remarks

Shell distinguished from all other discoid cyclophorids by the presence of a deep, tunnel-like sutural canal which begins as a tube-like peristomal folding at the suture part of the aperture.

Distinguished from congeners by its small to large shell, pronounced spiral ridges and somewhat keeled periphery. Colour pattern highly variable.

Genus Lagocheilus Blanford, 1864

Lagocheilus ‘kinta 1’

Figure 7A

Materials examined

Prk 53 Hill KF: BOR/MOL 10721, BOR/MOL 10677. mykarst-184 Bat Cave: BOR/MOL 9771, BOR/MOL 9813. Prk 36 Gua Datok: BOR/MOL 10421, BOR/MOL 10449, BOR/MOL 10481, BOR/MOL 10500. Prk 42 G. Bercham: BOR/MOL 10598. Prk 01 G. Tempurung: BOR/MOL 11238, BOR/MOL 11394, BOR/MOL 11427.

Distribution

Known from Kinta Valley only.

Remarks

Shell small, conical. Spire tall. Rounded dorsal whorls with numerous spiral ridges. Distinguished from Lagocheilus kobelti by its circular and flat peristome.

Remarks

Shell small, conical. Spire tall. Similar to Lagocheilus kobelti in the presence of angled dorsal whorls at major spiral rib but penultimate whorl is more expanded and shell larger (Sykes 1903).

Genus Leptopoma Pfeiffer, 1847

Distinguished from Opisthoporus penangensis (Stoliczka, 1872) by the pneumatophore being longer and further from the aperture and the presence of a wing-like sutural extension at the peristome.

Opisthoporus solutus (Stoliczka, 1872)

Figure 8C

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9892, BOR/MOL 9810. Prk 36 Gua Datok: BOR/MOL 10065, BOR/MOL 10473, BOR/MOL 10489. Prk 64 Bt Kepala Gajah: BOR/MOL 10107, BOR/MOL 10133, BOR/MOL 10164. Prk 55 G. Pondok: BOR/MOL 11504, BOR/MOL 11534, BOR/MOL 11477, BOR/MOL 11552, BOR/MOL 11566, BOR/MOL 11577.

Distribution

Known from Penang and Perak only (Maassen 2001).

Remarks

Differ from sympatric congeners by its patternless white shell and the yellow periostracum with equidistant spiral periostracal ridges.

Genus Platyraphe von Möllendorff, 1890

Platyraphe ‘batukebelah 1’

Figure 8D

Materials examined

mykarst-185 Batu Kebelah: BOR/MOL 9752. Prk 64 Bt Kepala Gajah: BOR/MOL 10097, BOR/MOL 10146, BOR/MOL 10187.

Distribution

Known from Batu Kebelah and Bukit Kepala Gajah, Perak only, but surrounding hills have yet to be adequately surveyed.

Remarks

Very small shell at maturity compared to all congeners. Shell discoid. Medium spire. Fine spiral ridges and radial ridges interspersed with major radial ridges at regular intervals. Often encrusted with mud and plant debris.

Shell dextral, very small. Cylindrical, tall spire. Radial ribs dense, spiral ridges very fine. Differ from Arinia (Notharinia) ‘tasek 1’ in the final whorl being less detached.

Figure 9.

AArinia (Notharinia) micro Marzuki & Foon, 2016 BOR/MOL 10288. Perak, Ipoh, Gunung Rapat BArinia (Notharinia) ‘tasek 1’ BOR/MOL 11193. Perak, Ipoh, Gunung Tasek Plot 2 CDiplommatina cf. diminuta BOR/MOL 9023. Perak, Ipoh, Gunung Kanthan Plot 1.D. Diplommatina crosseana Godwin-Austen & Nevill, 1879 BOR/MOL 9021. Perak, Ipoh, Gunung Kanthan.

Arinia (Notharinia) ‘tasek 1’

Figure 9B

Materials examined

Prk 34 G. Tasek: BOR/MOL 11166, BOR/MOL 11193.

Distribution

Known from Gunung Tasek only, but surrounding hills have yet to be adequately surveyed.

Remarks

Shell dextral, very small. Cylindrical, tall spire. Radial ribs dense, spiral ridges very fine. Differ from Arinia (Notharinia) micro in that the final whorl is completely detached and coiled downwards.

Shell sinistral. Shell large among congeners. The characters distinguishing Diplommatina lenggongensis from congeners: Spire very tall, slender. Suture deep. Radial ribs pronounced, extending outwards as a triangular protrusion along the periphery.

Remarks

Shell dextral, rarely sinistral. Distinct from all sympatric congeners by its rather distended ultimate whorl and reflected aperture which extends to the right of the body whorl. Sinistral specimens of this species were labelled as Diplommatina sp. in Davison (1991).

Figure 11.

A Diplommatina streptophora Laidlaw, 1949 BOR/MOL 9061. Perak, Ipoh, Gunung Kanthan Plot 3 B Diplommatina superba superba Godwin-Austen & Nevill, 1879 BOR/MOL 11557. Perak, Ipoh, Gunung Pondok C Diplommatina ventriculus (von Möllendorff, 1891) BOR/MOL 9027. Perak, Ipoh, Gunung Kanthan.

Diplommatina superba superba Godwin-Austen & Nevill, 1879

Figure 11B

Materials examined

Prk 47 Kanthan: BOR/MOL 9181, BOR/MOL 9063. Prk 53 Hill KF: BOR/MOL 10709, BOR/MOL 10733, BOR/MOL 10747, BOR/MOL 10682. Prk 23 G. Rapat: BOR/MOL 10217, BOR/MOL 10039, BOR/MOL 10247, BOR/MOL 10272. mykarst-027: BOR/MOL 9123, BOR/MOL 9017. mykarst-185 Batu Kebelah: BOR/MOL 9745. Prk 64 Bt Kepala Gajah: BOR/MOL 10154. Prk 36 Gua Datok: BOR/MOL 10435, BOR/MOL 10464. Prk 42 G. Bercham: BOR/MOL 10611. Prk 01 G. Tempurung: BOR/MOL 11153, BOR/MOL 11233, BOR/MOL 11406, BOR/MOL 11428. Prk 34 G. Tasek: BOR/MOL 11165. Prk 55 G. Pondok: BOR/MOL 11516, BOR/MOL 11586, BOR/MOL 11557.

Distribution

Known from Gunung Pondok and Kinta Valley only (Maassen 2001).

Remarks

Shell sinistral. Shell vary greatly in height and width, rib density, rib height and aperture thickness within and between populations. Consistent features are keeled periphery and whorl shape. After examining large samples from our study sites, we conclude that it is not possible to separate Diplommatina superba superba from Diplommatina superba brevior Laidlaw, 1949.

Diplommatina ventriculus (von Möllendorff, 1891)

Figure 11C

Materials examined

Prk 53 Hill KF: BOR/MOL 10703, BOR/MOL 10745, BOR/MOL 10725, BOR/MOL 10681. mykarst-184 Bat Cave: BOR/MOL 9883, BOR/MOL 9821. Prk 47 Kanthan: BOR/MOL 9180, BOR/MOL 9086. Prk 23 G. Rapat: BOR/MOL 10219, BOR/MOL 10265. mykarst-027: BOR/MOL 9117, BOR/MOL 9018, BOR/MOL 9027. Prk 64 Bt Kepala Gajah: BOR/MOL 10157. Prk 55 G. Pondok: BOR/MOL 11493, BOR/MOL 11518, BOR/MOL 11554, BOR/MOL 11582. Prk 34 G. Tasek: BOR/MOL 11191. Prk 01 G. Tempurung: BOR/MOL 11234, BOR/MOL 11404.

Distribution

Found throughout Peninsular Malaysia (Maassen 2001). Elsewhere, in Sumatra, Indonesia (van Benthem Jutting 1959).

Remarks

Shell dextral, rarely sinistral. Distinguished from other sympatric dextral congeners by its large shell, more globular whorls and weak columellar tooth.

Genus Opisthostoma Blanford & Blanford, 1860

Opisthostoma castor van Benthem Jutting, 1952

Figure 12A

Materials examined

Prk 64 Bt Kepala Gajah: BOR/MOL 10115, BOR/MOL 10147, BOR/MOL 10193.

Distribution

Restricted to Lenggong, Perak only (Maassen 2001).

Remarks

See the Remarks section of Opisthostoma fallax.

Remarks

Similar to Opisthostoma castor in shell shape, differ in convexity of the whorl, larger umbilicus and the position of the ultimate whorl relative to the penultimate whorl (van Benthem Jutting 1961a).

Remarks

Variable in spire height and the position of the apical whorls. Most similar to Opisthostoma ‘Kanthan 1’ but differ in the direction the aperture is facing as well as the less dense and more pronounced radial ribs.

Remarks

Distinguished from congeners by its shell shape and the presence of four coiling axes. Differ from Opisthostoma cf. vermiculum only in the coiling axis of the apical and antepenultimate whorls.

Family Pupinidae Pfeiffer, 1853a

Genus Pollicaria Gould, 1856

Pollicaria elephas (de Morgan, 1885)

Figure 15A

Materials examined

mykarst-027: BOR/MOL 9089, BOR/MOL 9030. Prk 53 Hill KF: BOR/MOL 10714, BOR/MOL 10741, BOR/MOL 10657, BOR/MOL 10684. mykarst-025: BOR/MOL 9402, BOR/MOL 9432, BOR/MOL 9443, BOR/MOL 9498. mykarst-185 Batu Kebelah: BOR/MOL 9567, BOR/MOL 9579. Prk 01 G. Tempurung: BOR/MOL 11138.

Distribution

Known from Pluss (=Pelus) River Valley and Kinta Valley, Perak only (Maassen 2001).

Remarks

Shell large. Operculum hard, calcified, multilamella. Distinct from any sympatric land snail species in the structure and coiling of the whorls.

Figure 15.

A Pollicaria elephas (de Morgan, 1885a) BOR/MOL 9443. Perak, Ipoh, Mykarst-025 Plot 1 B Pupina artata Benson, 1856 BOR/MOL 9803. Perak, Ipoh, Bat Cave Hill Plot 2 C Pupina arula perakensis von Möllendorff, 1891 BOR/MOL 10566. Perak, Ipoh, Gunung Datok Plot D Pupina lowi de Morgan, 1885a BOR/MOL 9873. Perak, Ipoh, Bat Cave Hill Plot 4.

Known from Perak only (Maassen 2001).

Remarks

Shell colour brown, glossy when alive. Variable in shell size. Whorls slender. Spire tall. Distinguished from congeners by the peristomal thickening and curvature of the aperture and its canals in mature shells.

Figure 16.

A Pupina tchehelensis de Morgan, 1885b BOR/MOL 11393. Perak, Ipoh, Gunung Tempurung Plot 2 B Schistoloma sectilabrum (Gould, 1844) BOR/MOL 8103. Perak, Ipoh, forested slope behind village at Gunung Pondok C Georissa monterosatiana Godwin-Austen & Nevill, 1879 BOR/MOL 11524. Perak, Ipoh, Gunung Pondok D Georissa semisculpta Godwin-Austen & Nevill, 1879 BOR/MOL 11047. Perak, Ipoh, Gunung Tasek.

Genus Schistoloma Kobelt, 1902

Schistoloma sectilabrum (Gould, 1844)

Figure 16B

Materials examined

Prk 47 Kanthan: BOR/MOL 9184. mykarst-184 Bat Cave: BOR/MOL 9765, BOR/MOL 9798.

Distribution

In Peninsular Malaysia, known from Penang, Perak and Pahang (Maassen 2001, Tumpeesuwan and Panha 2008). Elsewhere, in Petchaburi, Thailand as well as Tavoy (=Dawei) and Tenasserim (=Tanintharyi), Myanmar (Tumpeesuwan and Panha 2008).

Remarks

Shell colour brown. Spire tall. Peristome thin, reflected and expanded. Differ from Pupina species in the lack of apertural canals. Differ from Pollicaria species in its smaller size and straighter coiling axis.

Unranked clade: Neritimorpha

Family Hydrocenidae Troschel, 1857

Genus Georissa Blanford, 1864

Georissa monterosatiana Godwin-Austen & Nevill, 1879

Figure 16C

Remarks

Small shell. Distinguished from others by its oviform shell and truncated columella with two lamella teeth (one more pronounced than the other). This is a new record for Perak.

Figure 17.

A Elasmias terrestre (Brazier, 1876) BOR/MOL 10186. Perak, Ipoh, Gua Tok Giring Plot 4 B Achatina fulica (Bowdich, 1822) BOR/MOL 11208. Perak, Ipoh, Gunung Tempurung Plot 3 C Ariophanta lahatensis de Morgan, 1885a BOR/MOL 8275. Perak, Ipoh, Iron hill summit trail D Hemiplecta cymatium (Pfeiffer, 1856) BOR/MOL 11611. Perak, Ipoh, Gunung Pondok, plot 5 E Macrochlamys ‘Batu Kebelah 1’ BOR/MOL 9528. Perak, Ipoh, Batu Kebelah Plot 1.

Family Achatinidae Swainson, 1840

Genus Achatina Lamarck, 1799

Achatina fulica (Bowdich, 1822)

Figure 17B

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9860. mykarst-025: BOR/MOL 9378, BOR/MOL 9438, BOR/MOL 9497. mykarst-027: BOR/MOL 9046, BOR/MOL 9102. Prk 47 Kanthan: BOR/MOL 9049, BOR/MOL 9141. Prk 42 G. Bercham: BOR/MOL 9207, BOR/MOL 10570. mykarst-185 Batu Kebelah: BOR/MOL 9525, BOR/MOL 9558, BOR/MOL 9568, BOR/MOL 9582. Prk 64 Bt Kepala Gajah: BOR/MOL 10176. Prk 34 G. Tasek: BOR/MOL 10785, BOR/MOL 11025, BOR/MOL 11061, BOR/MOL 11171. Prk 01 G. Tempurung: BOR/MOL 11208, BOR/MOL 11239.

Distribution

Widespread in Peninsular Malaysia (Maassen 2001). Elsewhere, native to tropical Africa but now pantropical (Fontanilla et al. 2014).

Remarks

Large shell. Tall-spired with distinct stripes or flammulations. This is a synanthropic species.

Medium-sized shell. Whorls more tightly coiled than congeners, spire flat. Reddish brown shell with pronounced undulations of radial growth lines along the suture.

Macrochlamys ‘Bercham 1’

Figure 18A

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9861, BOR/MOL 9828, BOR/MOL 9775, BOR/MOL 9806. Prk 53 Hill KF: BOR/MOL 10737, BOR/MOL 10771, BOR/MOL 10777, BOR/MOL 10676. Prk 42 G. Bercham: BOR/MOL 9468, BOR/MOL 9477, BOR/MOL 9212, BOR/MOL 9239, BOR/MOL 10645. Prk 23 G. Rapat: BOR/MOL 10223, BOR/MOL 10281, BOR/MOL 10283. mykarst-027: BOR/MOL 9199. Prk 47 Kanthan: BOR/MOL 9203. mykarst-185 Batu Kebelah: BOR/MOL 9556, BOR/MOL 9572, BOR/MOL 9588. Prk 36 Gua Datok: BOR/MOL 10081, BOR/MOL 10466, BOR/MOL 10483. Prk 34 G. Tasek: BOR/MOL 11011.

Distribution

Known from Kinta Valley, Perak only.

Remarks

Shell small relative to congeners. Rounded periphery, spire relatively tall, whorls wide. Overall, shell looks glossy. Radial sculpture indistinct, spiral grooves distinct but very fine. Suture indistinct. Most similar to Macrochlamys malayana (von Möllendorff, 1891), which differs in being more globose and has less whorls.

Remarks

Shell small relative to congeners. Rounded periphery, spire relatively tall, whorls wide. Overall, shell looks glossy. Radial sculpture more indistinct than Macrochlamys ‘Bercham 1’, spiral grooves indistinct and very fine. Suture distinct, each whorl distinguished by its convexity. Most similar to Macrochlamys ‘Bercham 1’.

Genus Microcystina Mörch, 1872

Microcystina clarkae Maassen, 2000

Figure 19A

Materials examined

Prk 47 Kanthan: BOR/MOL 9186, BOR/MOL 9193. mykarst-184 Bat Cave: BOR/MOL 9852, BOR/MOL 9887, BOR/MOL 9792, BOR/MOL 9812. mykarst-185 Batu Kebelah: BOR/MOL 9760, BOR/MOL 9555. Prk 53 Hill KF: BOR/MOL 10758, BOR/MOL 10764, BOR/MOL 10768, BOR/MOL 10774. mykarst-025: BOR/MOL 9399, BOR/MOL 9428, BOR/MOL 9495. mykarst-027: BOR/MOL 9453, BOR/MOL 9201. Prk 42 G. Bercham: BOR/MOL 10650, BOR/MOL 9237. Prk 36 Gua Datok: BOR/MOL 10072, BOR/MOL 10080, BOR/MOL 10438. Prk 64 Bt Kepala Gajah: BOR/MOL 10108, BOR/MOL 10159, BOR/MOL 10195. Prk 55 G. Pondok: BOR/MOL 11602, BOR/MOL 11606, BOR/MOL 11593, BOR/MOL 11594. Prk 34 G. Tasek: BOR/MOL 11122, BOR/MOL 11127, BOR/MOL 11198, BOR/MOL 11199. Prk 01 G. Tempurung: BOR/MOL 11442, BOR/MOL 11445.

Distribution

In Peninsular Malaysia, only known from Perak. Elsewhere, in Sumatra, Indonesia (Maassen 2000).

Remarks

Very small shell. Easily distinguished from congeners by its white shell, tight whorls, fine radial ribs and finer spiral pits. This is a new record for Peninsular Malaysia.

Remarks

Dome shaped spire, netted sculpture.

Figure 20.

Widespread in Peninsular Malaysia (Maassen 2001). Native to East and Southeast Asia but now pantropical (de Winter et al. 2009).

Remarks

Medium-sized shell. Globular shell. Spire height low to medium. Umbilicus present. Periphery reflected when mature. Shell white to brown, occasionally with dark brown peripheral band. This is a synanthropic species.

Figure 21.

A Bradybaena similaris (Férussac, 1821) BOR/MOL 9376. Perak, Ipoh, Mykarst-025 Plot 1 B Amphidromus atricallosus perakensis (Fulton, 1901) BOR/MOL 8285. Perak, Ipoh, outcrop 500m C Chloritis breviseta (Pfeiffer, 1862) BOR/MOL 9091. Perak, Ipoh, Gunung Kanthan Plot 2 D Chloritis penangensis (Stoliczka, 1873) BOR/MOL 11562. Perak, Ipoh, Gunung Pondok, plot 6 E Trachia wrayi (de Morgan, 1885b) BOR/MOL 9381. Perak, Ipoh, Mykarst-025 Plot 1.

Family Camaenidae Pilsbry, 1895

Genus Amphidromus Albers, 1850

Amphidromus atricallosus perakensis (Fulton, 1901)

Figure 21B

Materials examined

Prk 47 Kanthan: BOR/MOL 9051.mykarst-027: BOR/MOL 9103. Prk 23 G. Rapat: BOR/MOL 10028. Prk 01 G. Tempurung: BOR/MOL 11139, BOR/MOL 11210, BOR/MOL 11243.

Distribution

Widespread in Peninsular Malaysia (Maassen 2001, Tan et al. 2011).

Remarks

Large shell. Tall spire. Dimorphic coiling within populations, with dextral and sinistral individuals. Shell lemon yellow throughout, with white sub-sutural line. Prior to this, among Kinta Valley limestone hills, Davison (1991) reported A. atricallosus perakensis from Gunung Kanthan only.

Genus Chloritis Beck, 1837

Chloritis breviseta (Pfeiffer, 1862)

Figure 21C

Materials examined

mykarst-027: BOR/MOL 9091, BOR/MOL 9016. Prk 47 Kanthan: BOR/MOL 9054, BOR/MOL 9137.

Distribution

In Peninsular Malaysia, known from Kelantan and Perak (Maassen 2001). Elsewhere, in Thailand (Maassen 2001).

Remarks

Medium-sized shell. Spire almost flat. Peristome reflected, more outwardly elongated than Chloritis penangensis. Shell flatter than C. penangensis.

Chloritis penangensis (Stoliczka, 1873)

Figure 21D

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9881. Prk 53 Hill KF: BOR/MOL 10715, BOR/MOL 10659. mykarst-025: BOR/MOL 9379, BOR/MOL 9405, BOR/MOL 9433, BOR/MOL 9501. mykarst-027: BOR/MOL 9093. Prk 42 G. Bercham: BOR/MOL 9469, BOR/MOL 9209, BOR/MOL 10589, BOR/MOL 10615, BOR/MOL 10637. Prk 23 G. Rapat: BOR/MOL 10229, BOR/MOL 10038, BOR/MOL 10050, BOR/MOL 10252. Prk 36 Gua Datok: BOR/MOL 10075, BOR/MOL 10413, BOR/MOL 10447, BOR/MOL 10477, BOR/MOL 10493. Prk 55 G. Pondok: BOR/MOL 11503, BOR/MOL 11543, BOR/MOL 11562. Prk 34 G. Tasek: BOR/MOL 11062, BOR/MOL 11190. Prk 01 G. Tempurung: BOR/MOL 11380.

Distribution

Known from Penang and Perak only (Maassen 2001).

Remarks

Medium-sized shell. Spire almost flat. Peristome reflected, more rounded than Chloritis breviseta. Shell more globular than C. breviseta.

Genus Trachia Albers, 1860

Trachia wrayi (de Morgan, 1885b)

Figure 21E

Materials examined

mykarst-025: BOR/MOL 9381. Prk 34 G. Tasek: BOR/MOL 10789. Prk 01 G. Tempurung: BOR/MOL 11246.

Distribution

Known from Kinta Valley only (Maassen 2001).

Remarks

Medium-sized shell. Spire almost flat. Periphery keeled. Peristome reflected. Reflected upper peristome slightly distended towards the periphery.

Family Charopidae Hutton, 1884

Genus Charopa von Martens, 1860

Charopa ‘Kanthan 1’

Figure 22A

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9889, BOR/MOL 9774, BOR/MOL 9807, BOR/MOL 9843. mykarst-185 Batu Kebelah: BOR/MOL 9759, BOR/MOL 9552. Prk 53 Hill KF: BOR/MOL 10760, BOR/MOL 10762, BOR/MOL 10767, BOR/MOL 10773. Prk 23 G. Rapat: BOR/MOL 10221, BOR/MOL 10042, BOR/MOL 10275, BOR/MOL 10280. Prk 42 G. Bercham: BOR/MOL 10649, BOR/MOL 9225. Prk 47 Kanthan: BOR/MOL 9188, BOR/MOL 9196. mykarst-027: BOR/MOL 9198.mykarst-025: BOR/MOL 9520. Prk 36 Gua Datok: BOR/MOL 10071, BOR/MOL 10076, BOR/MOL 10083, BOR/MOL 10436. Prk 55 G. Pondok: BOR/MOL 11599, BOR/MOL 11604, BOR/MOL 11607, BOR/MOL 11590. Prk 34 G. Tasek: BOR/MOL 11120, BOR/MOL 11125, BOR/MOL 11021, BOR/MOL 11196. Prk 01 G. Tempurung: BOR/MOL 11441, BOR/MOL 11444, BOR/MOL 11455.

Distribution

Known from Gunung Pondok and Kinta Valley, Perak only.

Remarks

Small shell. Whorls lesser than congeners. Dense nodules in all whorls. Latter whorls sometimes have nodules fused into wavy radial ridges. Shell white.

Figure 22.

Prk 23 G. Rapat: BOR/MOL 10029, BOR/MOL 10236, BOR/MOL 10256. Prk 36 Gua Datok: BOR/MOL 10469, BOR/MOL 10498. Prk 01 G. Tempurung: BOR/MOL 11149, BOR/MOL 11412. Prk 34 G. Tasek: BOR/MOL 11005, BOR/MOL 11194.

Distribution

Known from Perlis, Kedah, Penang, Perak, Kelantan and Pahang (Maassen 2001).

Remarks

Shell Spire very tall, slender. Aperture small. Shell smaller and lamella more pronounced than Phaedusa filicostata tenuicosta (Loosjes 1953).

Figure 23.

Known from Lenggong and Kramat Pulai, Perak only (Maassen 2001).

Remarks

Distinguished from congeners by its very cylindrical, tall spire shell, dense radial ribbing and slightly concaved central whorls (van Benthem Jutting 1961b).

Remarks

Distinguished from Perak congeners by the box-like shell shape, fewer whorls of gradually increasing height, widely spaced radial ribs, flared peristome and peristomal structures.

Figure 25.

A Sinoennea tweediei Tomlin, 1941 BOR/MOL 10100. Perak, Ipoh, Gua Tok Giring Plot 1 B Pseudoplecta bijuga (Stoliczka, 1873) BOR/MOL 11213. Perak, Ipoh, Gunung Tempurung Plot 3 C Quantula striata (Gray, 1834) BOR/MOL 9857. Perak, Ipoh, Bat Cave Hill Plot 4 D Glyptaulax ‘tempurung 1’ BOR/MOL 11147. Perak, Ipoh, Gunung Tempurung Plot 1.

Family Dyakiidae Gude & Woodward, 1921

Genus Pseudoplecta Laidlaw, 1932

Pseudoplecta bijuga (Stoliczka, 1873)

Figure 25B

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9856, BOR/MOL 9764, BOR/MOL 9796, BOR/MOL 9826. Prk 53 Hill KF: BOR/MOL 10710, BOR/MOL 10739, BOR/MOL 10660, BOR/MOL 10687. mykarst-025: BOR/MOL 9375, BOR/MOL 9403, BOR/MOL 9435, BOR/MOL 9502. Prk 47 Kanthan: BOR/MOL 9065, BOR/MOL 9138. mykarst-027: BOR/MOL 9100. Prk 23 G. Rapat: BOR/MOL 10227, BOR/MOL 10044, BOR/MOL 10049, BOR/MOL 10251. Prk 42 G. Bercham: BOR/MOL 9213, BOR/MOL 9231, BOR/MOL 10571, BOR/MOL 10590, BOR/MOL 10616. Prk 36 Gua Datok: BOR/MOL 10431, BOR/MOL 10443, BOR/MOL 10478, BOR/MOL 10495. Prk 34 G. Tasek: BOR/MOL 10790, BOR/MOL 11168, BOR/MOL 11052. Prk 01 G. Tempurung: BOR/MOL 11133, BOR/MOL 11213, BOR/MOL 11242, BOR/MOL 11418. Prk 55 G. Pondok: BOR/MOL 11507, BOR/MOL 11480, BOR/MOL 11540.

Distribution

In Peninsular Malaysia, found in Kedah (Langkawi), Penang, Perak, Selangor and Pahang (Cameron Highlands) (Laidlaw 1932, Maassen 2001). Elsewhere, in Nawngchik (=Pattani) and Rhaman (=Yala), Thailand (Maassen 2001).

Remarks

Shell medium-sized, brown. Periphery strongly keeled. Dorsal whorls have dense and pronounced sradial ribbing while the umbilical side is glossy with fine radial growth lines.

Genus Quantula Baker, 1941

Quantula striata (Gray, 1834)

Figure 25C

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9857, BOR/MOL 9827. mykarst-027: BOR/MOL 9092. mykarst-185 Batu Kebelah: BOR/MOL 9122, BOR/MOL 9526, BOR/MOL 9557. Prk 47 Kanthan: BOR/MOL 9142. mykarst-025: BOR/MOL 9503. Prk 42 G. Bercham: BOR/MOL 10569.

Distribution

Found throughout Peninsular Malaysia (Maassen 2001). Elsewhere, on Sundaland and the Philippines (Maassen 2001, Brodie and Barker 2012). Also, introduced into Fiji (Brodie and Barker 2012).

Remarks

Shell medium-sized. Brown and non-glossy at dorsal whorls, white and glossy at umbilicus. Periphery keeled but less pronounced than Pseudoplecta bijuga. Whorls have dense and fine radial growth lines. This is a synanthropic species.

Family Endodontidae Pilsbry, 1895

Genus Glyptaulax Gude, 1914

In Peninsular Malaysia, known from Perak, Johor (Pulau Aur) and Kelantan although it is likely widespread (Maassen 2001). Elsewhere, from Sundaland to Australia, Fiji and Samoa (Vermeulen et al. 2015).

Remarks

Distinguished from Kaliella barrakporensis by its straighter spire, less convex whorls and predominant spiral sculpture.

Figure 27.

A Kaliella microconus (Mousson, 1865) BOR/MOL 9551. Perak, Ipoh, Batu Kebelah Plot 1 B Kaliella scandens (Cox, 1871) BOR/MOL 11043. Perak, Ipoh, Gunung Tasek Plot 1 C Rahula ‘tempurung 1’ BOR/MOL 11392. Perak, Ipoh, Gunung Tempurung Plot 2 D Cecilioides caledonica (Crosse, 1867) BOR/MOL 9748. Perak, Ipoh, Batu Kebelah Plot 4.

Kaliella scandens (Cox, 1871)

Figure 27B

Materials examined

Prk 47 Kanthan: BOR/MOL 9076, BOR/MOL 9155, BOR/MOL 9167. mykarst-027: BOR/MOL 9040, BOR/MOL 9131. Prk 53 Hill KF: BOR/MOL 10751, BOR/MOL 10763, BOR/MOL 10731, BOR/MOL 10668, BOR/MOL 10693. mykarst-184 Bat Cave: BOR/MOL 9870, BOR/MOL 9786, BOR/MOL 9819, BOR/MOL 9836. mykarst-025: BOR/MOL 9392, BOR/MOL 9424, BOR/MOL 9517. Prk 42 G. Bercham: BOR/MOL 9480, BOR/MOL 9221, BOR/MOL 10582, BOR/MOL 10603, BOR/MOL 10618, BOR/MOL 10638. Prk 23 G. Rapat: BOR/MOL 10211, BOR/MOL 10045, BOR/MOL 10276, BOR/MOL 10282. mykarst-185 Batu Kebelah: BOR/MOL 9536, BOR/MOL 9590. Prk 36 Gua Datok: BOR/MOL 10058, BOR/MOL 10425. Prk 64 Bt Kepala Gajah: BOR/MOL 10103, BOR/MOL 10151, BOR/MOL 10177. Prk 34 G. Tasek: BOR/MOL 11019, BOR/MOL 11164, BOR/MOL 11004, BOR/MOL 11035, BOR/MOL 11043, BOR/MOL 11044, BOR/MOL 11057, BOR/MOL 11175, BOR/MOL 11184, BOR/MOL 11185. Prk 55 G. Pondok: BOR/MOL 11491, BOR/MOL 11529, BOR/MOL 11545, BOR/MOL 11571. Prk 01 G. Tempurung: BOR/MOL 11204, BOR/MOL 11225, BOR/MOL 11390, BOR/MOL 11425.

Distribution

Widespread in Peninsular Malaysia (Vermeulen et al. 2015). Elsewhere, from Sundaland to Australia and the Pacific islands (Vermeulen et al. 2015).

Remarks

Shell shape similar to Kaliella doliolum (Pfeiffer, 1846). Radial rib density highly variable, from very fine growth lines to coarse ribs. Distinguished from K. doliolum by the presence of fine spiral lines and absent or indistinct radial ribs at the umbilical section of the whorls. This is a synanthropic species.

Genus Rahula Godwin-Austen, 1907

Distribution

Known from Penang and Perak only (Maassen 2001).

Remarks

Shell small. Periphery rounded, whorls few, spire low. Surface glossy with very fine spiral lines. Sutural line distinct and white.

Figure 28.

A Helicarion permolle Stoliczka, 1873 BOR/MOL 9152. Perak, Ipoh, Gunung Kanthan Plot 4 B Discartemon leptoglyphus van Benthem Jutting, 1954 BOR/MOL 10479. Perak, Ipoh, Gunung Datok C Discartemon plussensis (de Morgan, 1885a) BOR/MOL 11031. Perak, Ipoh, Gunung Tasek

Family Streptaxidae Gray, 1860

Genus Discartemon Pfeiffer, 1856

Discartemon leptoglyphus van Benthem Jutting, 1954

Figure 28B

Materials examined

mykarst-027: BOR/MOL 9110, BOR/MOL 9013.mykarst-025: BOR/MOL 9412. Prk 42 G. Bercham: BOR/MOL 9466, BOR/MOL 10596. Prk 47 Kanthan: BOR/MOL 9143. Prk 23 G. Rapat: BOR/MOL 10048, BOR/MOL 10205, BOR/MOL 10232, BOR/MOL 10254. Prk 36 Gua Datok: BOR/MOL 10418, BOR/MOL 10446, BOR/MOL 10479, BOR/MOL 10492. Prk 34 G. Tasek: BOR/MOL 10794.

Distribution

Restricted to central Kinta Valley, Perak (Maassen 2001, Siriboon et al. 2014).

Remarks

Shell size varies. Differs from Discatemon plussensis in the prominence of lamella, presence of a peripheral keel and flatter shell.

Discartemon plussensis (de Morgan, 1885a)

Figure 28C

Materials examined

Prk 47 Kanthan: BOR/MOL 9056. Prk 42 G. Bercham: BOR/MOL 9458, BOR/MOL 9473, BOR/MOL 9476, BOR/MOL 9217, BOR/MOL 10620, BOR/MOL 10630. Prk 53 Hill KF: BOR/MOL 10695. Prk 23 G. Rapat: BOR/MOL 10260. Prk 34 G. Tasek: BOR/MOL 10795, BOR/MOL 11167, BOR/MOL 11031, BOR/MOL 11176. mykarst-027: BOR/MOL 9015. Prk 01 G. Tempurung: BOR/MOL 11145, BOR/MOL 11381, BOR/MOL 11413.

Distribution

Known from Perak only (Maassen 2001, Siriboon et al. 2014).

Remarks

Shell size varies. Differs from Discatemon leptoglyphus in the prominence of lamella, the absence of a peripheral keel and having more bulbous whorls. Prior to this, Davison (1991) reported D. plussensis from Gunung Tchehel and a few hills near Sungai Siput North only.

Genus Gulella Pfeiffer, 1856

Gulella bicolor (Hutton, 1834)

Figure 28D

Materials examined

mykarst-184 Bat Cave: BOR/MOL 9879. Prk 47 Kanthan: BOR/MOL 9159, BOR/MOL 9195. mykarst-185 Batu Kebelah: BOR/MOL 9540, BOR/MOL 9586.

Distribution

Found throughout Peninsular Malaysia (Maassen 2001). Elsewhere, pantropical (Simone 2013).

Remarks

Radial ribs faint to distinct. Distinguished from confamilals by its tall spire, cylindrical shell, compact whorls without detachment and its lamella arrangement. This is a synanthropic species.

Family Subulinidae Fischer & Crosse, 1877

Genus Allopeas Baker, 1935

Allopeas clavulinum (Potiez & Michaud, 1838)

Figure 29A

Materials examined

Prk 53 Hill KF: BOR/MOL 10700, BOR/MOL 10753, BOR/MOL 10722, BOR/MOL 10674. mykarst-184 Bat Cave: BOR/MOL 9876, BOR/MOL 9878, BOR/MOL 9801, BOR/MOL 9832, BOR/MOL 9769. Prk 47 Kanthan: BOR/MOL 9083, BOR/MOL 9145. mykarst-027: BOR/MOL 9037, BOR/MOL 9119. mykarst-025: BOR/MOL 9393, BOR/MOL 9409, BOR/MOL 9487, BOR/MOL 9512. Prk 42 G. Bercham: BOR/MOL 9465, BOR/MOL 9479, BOR/MOL 9215, BOR/MOL 10634, BOR/MOL 10635, BOR/MOL 10636. mykarst-185 Batu Kebelah: BOR/MOL 9539, BOR/MOL 9544, BOR/MOL 9583. Prk 64 Bt Kepala Gajah: BOR/MOL 10169. Prk 36 Gua Datok: BOR/MOL 10419, BOR/MOL 10487, BOR/MOL 10505. Prk 55 G. Pondok: BOR/MOL 11614. Prk 34 G. Tasek: BOR/MOL 11020, BOR/MOL 11160, BOR/MOL 11033, BOR/MOL 11038, BOR/MOL 11183. Prk 01 G. Tempurung: BOR/MOL 11150, BOR/MOL 11237, BOR/MOL 11386, BOR/MOL 11395, BOR/MOL 11430, BOR/MOL 11431.

Distribution

In Peninsular Malaysia, found in Perak and Kelantan but likely more widespread (Maassen 2001). Elsewhere, possibly native to tropical East Africa but now pantropical (Ho 1995, Vermeulen and Whitten 1998).

Remarks

Shell small, spire tall. Whorls more obtuse than Allopeas gracile. Spiral growth lines fine. This is a synanthropic species.

Distinguished from all confamilials by its glossy, large shell, very convex whorls, fine radial growth lines and truncated columella.

Family Trochomorphidae von Möllendorff, 1890

Genus Videna Adams & Adams, 1855

Videna castra (Benson, 1852b)

Figure 30A

Materials examined

Prk 47 Kanthan: BOR/MOL 9077, BOR/MOL 9172. mykarst-027: BOR/MOL 9090. Prk 53 Hill KF: BOR/MOL 10716, BOR/MOL 10663, BOR/MOL 10688. Prk 64 Bt Kepala Gajah: BOR/MOL 10093, BOR/MOL 10162. Prk 23 G. Rapat: BOR/MOL 10287. Prk 36 Gua Datok: BOR/MOL 10422, BOR/MOL 10457, BOR/MOL 10497. Prk 42 G. Bercham: BOR/MOL 10608. Prk 01 G. Tempurung: BOR/MOL 11135, BOR/MOL 11245, BOR/MOL 11384, BOR/MOL 11417. Prk 34 G. Tasek: BOR/MOL 11169. Prk 55 G. Pondok: BOR/MOL 11509, BOR/MOL 11481, BOR/MOL 11549, BOR/MOL 11570. mykarst-025: BOR/MOL 12429.

Distribution

Found throughout Peninsular Malaysia (Maassen 2001). Elsewhere, in Darjiling (=Darjeeling), India and Salang (=Phuket), Thailand (Maassen 2001).

Remarks

Distinguished from Peninsular Malaysian congeners by its distinct spiral lines at apical whorls, becoming less at post-apical whorls. Radial sculpture more prominent at post-apical whorls.

Figure 30.

A Videna castra (Benson, 1852b) BOR/MOL 11135. Perak, Ipoh, Gunung Tempurung Plot 1 B Gyliotrachela hungerfordiana (von Möllendorff, 1886) BOR/MOL 9133. Perak, Ipoh, Gunung Kanthan C Gyliotrachela luctans van Benthem Jutting, 1950 BOR/MOL 10064. Perak, Ipoh, Gunung Datok D Paraboysidia oreia van Benthem Jutting, 1961 BOR/MOL 10504. Perak, Ipoh, Gunung

Family Hypselostomatidae Zilch, 1959

Genus Gyliotrachela Tomlin, 1930

Gyliotrachela hungerfordiana (von Möllendorff, 1886)

Figure 30B

Materials examined

Prk 53 Hill KF: BOR/MOL 10701, BOR/MOL 10743, BOR/MOL 10726, BOR/MOL 10667. Prk 47 Kanthan: BOR/MOL 9073, BOR/MOL 9148. mykarst-184 Bat Cave: BOR/MOL 9871, BOR/MOL 9789, BOR/MOL 9804, BOR/MOL 9845. mykarst-025: BOR/MOL 9390, BOR/MOL 9419. Prk 42 G. Bercham: BOR/MOL 9461, BOR/MOL 9464, BOR/MOL 9483, BOR/MOL 10575, BOR/MOL 10602, BOR/MOL 10623. mykarst-027: BOR/MOL 9133, BOR/MOL 9241. mykarst-185 Batu Kebelah: BOR/MOL 9538, BOR/MOL 9747. Prk 23 G. Rapat: BOR/MOL 10040, BOR/MOL 10234, BOR/MOL 10262. Prk 64 Bt Kepala Gajah: BOR/MOL 10094, BOR/MOL 10142, BOR/MOL 10180. Prk 36 Gua Datok: BOR/MOL 10426, BOR/MOL 10458, BOR/MOL 10507. Prk 34 G. Tasek: BOR/MOL 11156, BOR/MOL 11002, BOR/MOL 11046, BOR/MOL 11181. Prk 55 G. Pondok: BOR/MOL 11513, BOR/MOL 11486, BOR/MOL 11548, BOR/MOL 11568.

Distribution

Found on limestone karsts across Peninsular Malaysia (Maassen 2001). Elsewhere, in southern Thailand (Maassen 2003).

Remarks

Distinct among congeners in its tall spire, keeled periphery, very long trumpet-shaped ultimate whorl and apertural teeth arrangement. Shell colour varies from dark to light brown.

Gyliotrachela luctans van Benthem Jutting, 1950

Figure 30C

Materials examined

Prk 36 Gua Datok: BOR/MOL 10064.

Distribution

Known from Gunung Pondok (van Benthem Jutting 1950) and Gua Datok, Perak only.

Remarks

Spire tall but fewer than Gyliotrachela hungerfordiana. Penultimate whorl very expanded and periphery keeled, giving a depressed shell shape. Ultimate whorl trumpet-shaped, with aperture face at 45 degrees of the plane perpendicular to the coiling axis. Apertural teeth arrangement unique.

Genus Paraboysidia Pilsbry, 1917

Paraboysidia oreia van Benthem Jutting, 1961a

Figure 30D

Materials examined

Prk 53 Hill KF: BOR/MOL 10727. Prk 47 Kanthan: BOR/MOL 9064, BOR/MOL 9175. mykarst-027: BOR/MOL 9125, BOR/MOL 9022. Prk 36 Gua Datok: BOR/MOL 10504. Prk 34 G. Tasek: BOR/MOL 11013, BOR/MOL 11039, BOR/MOL 11060.

Distribution

Known from Gunung Batu Kurau (van Benthem Jutting 1961) and Kinta Valley, Perak only.

Remarks

Shell small, dark brown. Spire tall. Whorls rather convex. Distinguished from Perak congeners by the slightly keeled periphery and apertural teeth arrangement.

Paraboysidia ‘tempurung 1’

Figure 31A

Materials examined

Prk 01 G. Tempurung: BOR/MOL 11217.

Distribution

Known from Gunung Tempurung, Perak only, but surrounding hills have yet to be adequately surveyed.

Remarks

Differ from Paraboysidia kelantanensis tenuidentata van Benthem Jutting, 1950, of Kramat Pulai by its gradually flatter and more expanded whorls, periphery rounded, shallow suture, short trumpet-like extension of ultimate whorl and apertural teeth arrangement.

Figure 31.

A Paraboysidia ‘tempurung 1’ BOR/MOL 11217. Perak, Ipoh, Gunung Tempurung Plot 3 B Ptychopatula orcula (Benson, 1850) BOR/MOL 9043. Perak, Ipoh, Gunung Kanthan Plot 1 C Ptychopatula solemi Maassen, 2000 BOR/MOL 9042. Perak, Ipoh, Gunung Kanthan Plot 1.

Family Vallonidae Morse, 1864

Genus Ptychopatula Pilsbry, 1889

Ptychopatula orcula (Benson, 1850)

Figure 31B

Materials examined

Prk 53 Hill KF: BOR/MOL 10708, BOR/MOL 10723. mykarst-184 Bat Cave: BOR/MOL 9862, BOR/MOL 9782, BOR/MOL 9815, BOR/MOL 9842. Prk 47 Kanthan: BOR/MOL 9078, BOR/MOL 9171. mykarst-027: BOR/MOL 9043, BOR/MOL 9118. mykarst-025: BOR/MOL 9391, BOR/MOL 9426, BOR/MOL 9488, BOR/MOL 9522. Prk 42 G. Bercham: BOR/MOL 9457, BOR/MOL 9463, BOR/MOL 9478, BOR/MOL 9219, BOR/MOL 10584, BOR/MOL 10599, BOR/MOL 10621, BOR/MOL 10631, BOR/MOL 10632. Prk 23 G. Rapat: BOR/MOL 10218, BOR/MOL 10036, BOR/MOL 10235, BOR/MOL 10269. mykarst-185 Batu Kebelah: BOR/MOL 9537, BOR/MOL 9743. Prk 64 Bt Kepala Gajah: BOR/MOL 10104, BOR/MOL 10148, BOR/MOL 10185. Prk 36 Gua Datok: BOR/MOL 10429, BOR/MOL 10471, BOR/MOL 10503. Prk 01 G. Tempurung: BOR/MOL 11144, BOR/MOL 11224, BOR/MOL 11426. Prk 34 G. Tasek: BOR/MOL 11163, BOR/MOL 11008, BOR/MOL 11042, BOR/MOL 11182. Prk 55 G. Pondok: BOR/MOL 11487, BOR/MOL 11526, BOR/MOL 11551.

Distribution

In Peninsular Malaysia, known from Perlis and Perak (Maassen 2001). Elsewhere, in the tropical regions of the Indian Ocean and the Pacific Islands (Seddon 2000).

Remarks

Distinguished from sympatric congener Ptychopatula solemi by its larger shell, wider whorls, wide umbilicus and lower spire.

Ptychopatula solemi Maassen, 2000

Figure 31C

Materials examined

Prk 47 Kanthan: BOR/MOL 9176, BOR/MOL 9068. mykarst-027: BOR/MOL 9042. mykarst-184 Bat Cave: BOR/MOL 9864, BOR/MOL 9818, BOR/MOL 9841. mykarst-185 Batu Kebelah: BOR/MOL 9548, BOR/MOL 9753. Prk 23 G. Rapat: BOR/MOL 10239. Prk 34 G. Tasek: BOR/MOL 11000.

Distribution

In Peninsular Malaysia, known from Perak only (Maassen 2001). Elsewhere, in Sumatra and Sulawesi, Indonesia (Maassen 2000).

Remarks

Distinguished from sympatric congener Ptychopatula orcula by its smaller shell, tighter whorls, narrower umbilicus and tall spire.

Discussion

Apart from providing a comprehensive assessment of land snail diversity for the limestone hills in and around the Kinta Valley of Perak, our study has also elucidated interesting biogeographical patterns to assist in conservation planning. Our study has also paved the way for more in-depth land snail taxonomy studies to be conducted. For instance, many of the land snail species recorded by Davison (1991) and Clements et al. (2008b) could not be assigned to scientific names that have been published, until now. Speciose genera such as Microcystina, Diplommatina and Opisthostoma, require critical taxonomic revisions that need considerable effort. We hope unnamed species in these genera, now with traceable reference specimens collected from our study, can be described in the near future.

Land snail species diversity and biogeographical patterns

Correlation tests initially suggested no statistically significant relationship between the number of unique species and the degree of limestone hill isolation. However, when examined closely within a geographical context, the number of unique species for each hill could also be associated with the degree of isolation of major limestone clusters of each hill (Table 1). For example, Prk 55 G. Pondok, Prk 64 Bt Kepala Gajah, and Prk 01 G. Tempurung all located in the limestone clusters at the periphery of Kinta Valley and at least 50 km away from other limestone clusters outside of Kinta Valley (see Figure 6 in Liew et al. 2016).

At this point in time, our assignment of unique species should be considered “unique” to a particular hill in the context of hills that have been surveyed systematically in our study. The degree of endemism of a species depends on the geographical context, e.g. endemic to Malaysia, Perak, Kinta Valley, hill clusters or a single hill. For example, Charopa lafargei which previously presumed as endemic to Gunung Kanthan (Vermeulen and Marzuki 2014), is shown in our study to also occur on the limestone hills at the north of Kinta Valley. Also, Hydrocena semisculpta which was thought be endemic to Gunung Pondok (Davison 1991), is a relatively widespread species – can be found in 11 out of the 12 hills surveyed in our study.

Our comprehensive inventory has corroborated Davison’s (1991) hypothesis that land snail assemblages on limestone hills in Perak can be divided into two groups, one comprising of hills within Kinta Valley and the other comprising of hills scattered in the area north of Kinta Valley. This biogeographical pattern cannot be explained by geographical distance between different limestone hills alone. For example, although Bat Cave Hill and Batu Kebelah Hill (northern cluster) are closest to Prk 53 Hill KF, the land snail assemblage of Prk 53 Hill KF is more similar to the land snail assemblages in the southern cluster hills.

It seems that biogeographical patterns of land snail assemblages at limestone hills in and around the Kinta Valley of Perak were influenced by the geology and topography of the area. For instance, all the hills in the southern cluster are located in the low-lying floodplains of the Kinta valley, while the hills of the northern cluster are located on hilly granitic areas north of the Kinta valley floodplain. As such, this biogeographical pattern could be a result of geological isolation (de Morgan 1885a; van Benthem Jutting 1960; Davison 1991).

The rocks in Perak (including limestone) first emerged in the Mesozoic – the Late Jurassic period (van Benthem Jutting 1960; Metcalfe 2013). After that, limestone hills in Perak became isolated due to two different processes that produced the two biogeographical regions (i.e. limestone hill clusters) (Paton 1961). For the northern hill cluster, the isolation of hills was likely to be caused by structural deformity with intrusion of granite and these hills were probably never contiguous from the start (Paton 1961). For the southern hill cluster, the isolation of hills was probably caused by limestone erosion, recent marine incursion and alluvial deposition (Paton 1961). However, our hypothesis of geological isolation being the main determinant of biogeographical patterns observed in our study requires further tests using phylogeographic approaches, where the divergence time of a particular land snail species can be estimated (by sampling populations from different limestone hills) and matched with historical geological events, including the more recent local geological events or climate changes in the Pleistocene.

Conservation implications

Despite containing the second highest number of limestone hills in Peninsular Malaysia after the State of Kelantan (see Liew et al. 2016), the State of Perak appears to be experiencing the greatest threat from limestone quarrying with 45 out of 78 limestone quarries in the peninsula being located in this State as of 2014 (Minerals and Geoscience Department Malaysia 2014). As such, there is an urgent need to identify limestone hills with high levels of species endemism for conservation prioritisation within this State. Four hills, namely Prk 01 G. Tempurung, Prk 55 G. Pondok, Prk 47 Kanthan, and Prk 64 Bt Kepala Gajah, were found to collectively contain 91% of the total land snail species occurring at 12 hills sampled in our study. In order to prevent the extinction of unique land snail species, these hills require immediate attention from conservation practitioners to mitigate ongoing threats from quarrying and surrounding forest loss.

Conclusion

Our study has updated the state of knowledge of land snail diversity and biogeography on limestone hills in Perak, Peninsular Malaysia. Larger limestone hills seem to have more unique species, of which several could be site endemic. In addition, we have shown that land snail assemblages can be divided into two groups that occupy limestone hills at two different areas in Perak – this was likely caused by different geological processes that separated the limestone hills. Most importantly, our findings can be used to assist in limestone conservation planning, especially within the Kinta Valley of Perak.

Acknowledgements

This project was supported by research grants from Lafarge Malaysia Sdn. Bhd. to Universiti Malaysia Sabah (GL00154). Research permits were obtained from Department of Wildlife and National Parks Peninsular Malaysia (JPHL&TN(IP): 100-34/1.24Jld6 (14)) and Perak Forestry Department (PPN.PK 600/03/01Jld 9(62); AM-PM-202-16). We thank Mohammad Effendi Marzuki, Rahmat Asod, Mahani Mohd Isa, Phung Chee Chean, Chee Huey Ying, Choo Ming Huei, Chua Wai Min, Gam Yin Cheng, Yong Yuen Zhao, Yeong Kam Cheng, Chang Zi Yuan, Jasrul Dulipat, Sook Hoon Yew and Wee Siaw Hwen for their assistance during field and laboratory work.

References

Adams H, Adams A (1855) The genera of recent Mollusca arranged according to their organization. Volume 1. John van Voorst, London, 484 pp. https://doi.org/10.5962/bhl.title.4772

Adams H, Adams A (1856) The genera of recent Mollusca arranged according to their organisation. Volume 2. John Van Voorst, London, 661 pp. https://doi.org/10.5962/bhl.title.4772

Albers JC (1850) Die Heliceen, nach natürlicher Verwandtschaft systematisch geordnet. Edition 1. Verlag von TCF Enslin, Berlin, 266 pp. https://doi.org/10.5962/bhl.title.11507

Albers JC (1860) Die Heliceen, nach natürlicher Verwandtschaft systematisch geordnet, Edition 2. Wilhelm Englemann, Leipzig, 359 pp. https://doi.org/10.5962/bhl.title.11218

Aldrich TH (1889) Notes on a collection of shells from Borneo, with descriptions of new species. Journal of the Cincinnati Society of Natural History 12: 23–26.

Baird W (1850) Nomenclature of Molluscous Animals and Shells in the collection of the British Museum Part 1. Cyclophoridae. Spottiswoodes and Shaw, London, 68 pp. https://doi.org/10.5962/bhl.title.59531

Baker HB (1928) Minute American Zonitidae. Proceedings of the Academy of Natural Sciences of Philadelphia 80: 1−44.

Baker HB (1935) Jamaican land snails 3. The Nautilus 48: 83–88. https://doi.org/10.5962/bhl.part.11532

Baker HB (1941) Zonitid snails from Pacific islands. Part 3 and 4. Bernice P. Bishop Museum Bulletin 166: 203–370.

Beck H (1837) Index molluscorum praesentis aevi Musei rincipis augustissimi Christiani Frederici. Copenhagen, 124 pp. https://doi.org/10.5962/bhl.title.77331

Benson WH (1849) Characters of Diplommatina, a new genus of terrestrial Mollusks belonging to the family of Carychiadae, and of a second species contained in it; also of a new species of Carychium inhabiting the Western Himalaya. The Annals and Magazine of Natural History series 2, 4: 193–195.

Benson WH (1850) Characters of new species of Helix from India, Mauritius and the Cape of Good Hope. The Annals and Magazine of Natural History series 2, 2: 251–256.

Benson WH (1852a) Notes on the genus Cyclostoma, and characters of some new species from India, Borneo, and Natal. The Annals and Magazine of Natural History series 5, 2: 268–272.

Benson WH (1852b) Notice of an Australian Diplommatina and characters of East Indian Helicidae from Darjeling and Singapore. The Annals and Magazine of Natural History series 2: 348–351.

Benson WH (1856) Characters of seventeen new forms of the Cyclostomacea from the British Provinces of Burmah collected by W. Theobald, Jun., Esq. The Annals and Magazine of Natural History series 2, 17: 225–233.

Benson WH (1860) On Clostophis and Rhiostoma, new Burmese genera of land shells. The Annals and Magazine of Natural History series 3, 5: 95–97.

van Benthem Jutting WSS (1941) Non-marine mollusca from the satellite islands surrounding Java. Archives Néerlandaises de Zoologie 5: 251–348.

van Benthem Jutting WSS (1950) The Malayan species of Boysidia, Paraboysidia, Hypselostoma and Gyliotrachela (Gastropoda, Pulmonata, Vertiginidae). Bulletin of the Raffles Museum 21: 5–47.

van Benthem Jutting WSS (1952) The Malayan species of Opisthostoma (Gastropoda, PROSOBRANCHIA, Cyclophoridae), with a catalogue of all the species hitherto described. Bulletin of the Raffles Museum 24: 5–62.

van Benthem Jutting WSS (1954) The Malayan Streptaxidae of the genera Discartemon and Oophana. Bulletin of the Raffles Museum 25: 71–106.

van Benthem Jutting WSS (1959) Catalogue of the non-marine Mollusca of Sumatra and of its satellite islands. Beaufortia 7: 41–191.

van Benthem Jutting WSS (1960) Non-marine mollusca of the limestone hills in Malaya. Proceedings of Centenary and Bicentary Congress of Biology. 63–68.

van Benthem Jutting WSS (1961a) Additional new species and new localities of the family Vertiginidae and the genera Oophana and Opisthostoma from Malaya. Bulletin of the Raffles Museum 26: 34–48.

van Benthem Jutting WSS (1961b) The Malayan Streptaxidae genera Huttonella and Sinoennea. Bulletin of the Raffles Museum 26: 5–33.

de Blainville HMD (1814) Mémoire sur la classification méthodique des animaux mollusques, et établissement d’une nouvelle considération pour y parvenir. Bulletin des Sciences par la Société Philomatique des Paris, Zoologie 1814: 175–180.

Blanford WT, Blanford HF (1861) Contributions to Indian malacology, no 2. Journal of the Asiatic Society of Bengal 30: 347–365.

Blanford WT (1863) On Indian species of land-shells belonging to the genera Helix, Linn., and Nanina, Gray. The Annals and Magazine of Natural History series 3, 11: 81–86.

Blanford WT (1864) On the classification of the Cyclostomacea of Eastern Asia. The Annals and Magazine of Natural History series 3, 13: 441–465.

Blanford WT (1869) On the animal and operculum of Georissa, W. Blanf., and on its relations to Hydrocena, Parreyss; with a note on Hydrocena tersa, Bens., and H. milium, Bens. The Annals and Magazine of Natural History series 4, 3: 173–179.

Bourguignat JR (1877) Description de deux nouveaux genres algériens, suivie d'une classification des familles et des genres de Mollusques terrestres et fluviatiles du système européen. Bulletin de la Société des Sciences physiques et naturelles de Toulouse 3: 49−101.

Bourguignat JR (1883) Histoire malacologique de l’Abyssinie. Annales des Sciences Naturelles, Zoologie series 6 15: 1−162. https://doi.org/10.5962/bhl.title.46223

Bowdich TE (1822) Elements of conchology, including the fossil genera and the animals. Part I. Univalves. J Smith, Paris, 73 pp. https://doi.org/10.5962/bhl.title.77504

Brazier J (1876) Descriptions of thirty-five new species of land shells from New Guinea, Australia, and islands in the Torres Straits, collected during the Chevert Expedition. Proceedings of the Linnean Society of New South Wales 1: 98–113. https://doi.org/10.5962/bhl.part.12393

Broderip WJ, Sowerby GB (1829) Observations on new or interesting Mollusca contained, for the most part, in the Museum of the Zoological Society. Zoological Journal 4: 359–379.

Brodie G, Barker GM (2012) Quantula striata (Gray, 1834). Family Ariophantidae. USP introduced land snails of the Fiji Islands fact sheet series no. 7. University of the South Pacific, Suva.

Bruguière JG (1792) Encyclopdie méthodique ou par ordre de matières. Histoire naturelle des vers. Volume 1, Part 2. Pancoucke, Paris, 344–758. https://doi.org/10.5962/bhl.title.8638

Chan SY (1998a) A brief collecting trip to Perak, West Malaysia. part one. The Papustyla 12(1): 4–5.

Chan SY (1998b) A brief collecting trip to Perak, West Malaysia. part two. The Papustyla 12(2): 1–2.

Chua LSL, Kiew R, Chan YM (2009) Assessing conservation status of Peninsular Malaysian Begonia (Begoniaceae). Blumea-Biodiversity, Evolution and Biogeography of Plants, 54(1-3), 94–98. https://doi.org/10.3767/000651909X474131

Chemnitz JH (1786) Neues systematisches Conchylien-Cabinet. Neunten Bandes zwote Abtheilung, enthaltend die ausführliche Beschreibung von den Land- und Flußschnecken, oder von solchen Conchylien welche nicht im Meer, sondern auf der Erde und in süssen Wassern zu leben pflegen. Mit zwanzig nach der Natur gemalten und durch lebendige Farben erleuchteten Kupfertafeln. Raspe, Nürnberg, 194 pp. https://doi.org/10.5962/bhl.title.43760

Clements R, Sodhi NS, Schilthuizen M, Ng PK (2006) Limestone karsts of Southeast Asia: imperiled arks of biodiversity. Bioscience, 56(9): 733–742. https://doi.org/10.1641/0006-3568(2006)56[733:LKOSAI]2.0.CO;2

Clements R, Liew T-S, Vermeulen JJ, Schilthuizen M (2008a) Further twists in gastropod shell evolution. Biology Letters 4: 179–182. https://doi.org/10.1098/rsbl.2007.0602

Clements R, Ng PK, Lu XX, Ambu S, Schilthuizen M, Bradshaw CJ (2008b) Using biogeographical patterns of endemic land snails to improve conservation planning for limestone karsts. Biological conservation, 141(11): 2751–2764. https://doi.org/10.1016/j.biocon.2008.08.011

Cox JC (1871) Description of a new Volute and twelve new species of land-shells from Australia and the Solomon Islands. Proceedings of the Zoological Society of London 1871: 643–647.

Cox LR (1960) Thoughts on the classification of the Gastropoda. Proceedings of the Malacological Society of London 33: 239−261.

Crosse H (1867) Description d’un genre nouveau et de plusieurs especes inedites provenant de la Nouvelle-Caledonie. Journal de conchyliologie 15: 312−336.

Crosse H (1879a) Mollusques nouvelles de Perak (Indo Chine). Journal de Conchyliologie 27: 198–208.

Crosse H (1879b) Faune malacologique de Perak (Indo-Chine). Journal de Conchyliologie 27: 336–340.

Cuvier G (1795) Second Mémoire sur l’organisation et les rapports des animaux à sang blanc, dans lequel on traite de la structure des Mollusques et de leur division en ordre, lu à la société d’Histoire Naturelle de Paris, le 11 prairial an troisième. Magazin Encyclopédique, ou Journal des Sciences, des Lettres et des Arts 2: 433–449.

Davison GWH (1991) A conservation assessment of limestone hills in the Kinta Valley. Final report – MNS Project 1/90, Malayan Nature Society. Page 1–202.

Desmoulins CM (1829) Notice sur un limaçon de la Côte de Malabar, observé vivant à Bordeaux. Bulletin de la Société linnéenne de Bordeaux 3: 227–238.

Dixon P (2003) VEGAN, a package of R functions for community ecology. Journal of Vegetation Science, 14(6): 927–930. https://doi.org/10.1111/j.1654-1103.2003.tb02228.x

Férussac AEJPJF (1814) Mémoires géologiques sur les terreins formés sous l’eau douce par les débris fossiles des mollusques vivant sur la terre ou dans l’eau non salée. Poulet, Paris, 76 pp.

Férussac AEJPJF (1821–1822) Tableaux systématiques des animaux mollusques classés en familles naturelles, dans lesquels on a établi la concordance de tous les systèmes; suivis d’un prodrome général pour tous les mollusques terrestres ou fluviatiles, vivants ou fossiles. Londres, Paris, 110 pp.

Fischer P, Crosse H (1877) Mission scientifique au Mexique et dans l’Amérique Centrale : ouvrage publié par ordre de S.M. l’Empereur et par les soins du Ministre de l’instruction publique. Etudes sur les mollusques terrestres et fluviatiles du Mexique et du Guatemala. 72 pp.

Fontanilla IKC, Sta. Maria IMP, Garcia JRM, Ghate H, Naggs F, Wade CM (2014) Restricted genetic variation in populations of Achatina (Lissachatina) fulica outside of East Africa and the Indian Ocean Islands points to the Indian Ocean Islands as the earliest known common source. PLoS One. 9: e105151. https://doi.org/10.1371/journal.pone.0105151

Fulton HC (1901) Descriptions of new species of Xesta, Amphidromus and Cyclostoma from Madagascar and Perak. Journal of Malacology 8: 103–104.

Fulton HC (1902) Descriptions of a new Alycaeus from Perak and a Bulimulus from Bolivia. The Annals and Magazine of Natural History series 7, 9: 68–69.

Godwin-Austen HH, Nevill G (1879) Descriptions of shells from Perak and the Nicobar Islands. Proceedings of the Zoological Society of London 1879: 734–740. https://doi.org/10.1111/j.1096-3642.1879.tb02710.x

Godwin-Austen HH (1882–1888) Land and Freshwater Mollusca of India, including South Arabia, Baluchistan, Afghanistan, Kashmir, Nepal, Burmah, Pegu, Tenasserim, Malay Peninsula, Ceylon, and other islands of the Indian Ocean. Supplementary to Messrs. Theobald and Hanley's Conchologia Indica. Volume 1. Taylor and Francis, London, 257 pp. https://doi.org/10.5962/bhl.title.12719

Godwin-Austen HH (1897–1914) Land and Freshwater Mollusca of India, including South Arabia, Baluchistan, Afghanistan, Kashmir, Nepal, Burmah, Pegu, Tenasserim, Malay Peninsula, Ceylon, and other islands of the Indian Ocean. Supplementary to Messrs. Theobald and Hanley's Conchologia Indica. Volume 2. Taylor and Francis, London, 442 pp. https://doi.org/10.5962/bhl.title.12719

Godwin-Austen HH (1898) On Philalanka, a new subgenus of Endodonta, with descriptions of two new species from the Indian region. Proceedings of the Malacological Society of London 3: 11–13.

Godwin-Austen HH (1909) Descriptions of the animals of two land shells from Perak “Skeat expedition in the Malay Peninsula. Journal of Molluscan Studies 8(6): 365–368.

Gould AA (1844) Descriptions of land shells from the province of Tavoy, in the British Burmah. Boston Journal of Natural History 4: 452–459.

Gould AA (1852) Mollusca and shells. In: Wilkes C (Ed) United States Exploring Expedition, during the year 1838, 1839, 1840, 1841, 1842; 12. Gould & Lincoln, Boston, 510 pp. https://doi.org/10.5962/bhl.title.61454

Gould AA (1856) Descriptions of shells. Proceedings of Boston Society of Natural History 6: 11–16.

de Grateloup JPS (1840) Description de plusieurs coquilles nouvelles ou peu connues de mollusques exotiques vivants. Actes de la Société Linnéenne de Bordeaux 11: 394–455.

Gray JE (1834) Descriptions various undescribed shells, chiefly contained in his own collection. Proceedings of the Zoological Society of London, 1834: 57–59.

Gray JE (1847) A list of the genera of recent Mollusca, their synonyms and types. Proceedings of the Zoological Society of London, 1847: 129–219.

Gray JE (1855) Catalogue of Pulmonata or air-breathing Mollusca in the collection of the British Museum, Part I. Taylor and Francis, London, 192 pp. https://doi.org/10.5962/bhl.title.21207

Gray JE (1860) On the arrangement of the land pulmoniferous Mollusca into families. The Annals and Magazine of Natural History Series 3, 6: 267–269.

Gude GK (1914) The fauna of British India including Ceylon and Burma. Mollusca II (Trochomorphidae-Janellidae). Taylor and Francis, London, 520 pp. https://doi.org/10.5962/bhl.title.48423

Gude GK, Woodward BB (1921) On Helicidae, Ferussac. Proceedings of Malacological Society of London 14: 174–190.

Gulick JT (1873) On the classification of the Achatinellinæ. Proceedings of the Zoological Society of London 1873: 89–91.

Ho WH (1995) A Review of the Land-snail Fauna of Singapore. Raffles Bulletin of Zoology 43: 91–113.

Hsieh TC, Ma KH, Chao A (2016) iNEXT: an R package for rarefaction and extrapolation of species diversity (Hill numbers). Methods in Ecology and Evolution, 7(12), 1451–1456. https://doi.org/10.1111/2041-210X.12613

Hutton T (1834) On the land shells of India. Journal of the Asiatic Society of Bengal 3: 81–93.

Hutton FW (1884) Revision of the land Mollusca of New Zealand. Transactions of the New Zealand Institute 16: 186–212.

Kiew R, Tan JP-C, Saleh K, Yong K-T, Kamin I (2014) An uncertain future for the plants of Gunung Kanthan, Perak, Malaysia. Cave and Karst Science 41(3): 120–128.

Kobelt W, von Möllendorff OF (1897) Catalog der gegenwärtig lebend bekannten Pneumonopomen. Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft 1(3): 73–192. https://doi.org/10.5962/bhl.title.14877

Kobelt W (1902) Cyclophoridae. Das Tierreich 16, Mollusca, 663 pp. https://doi.org/10.5962/bhl.title.1227

Kobelt W (1904) Die Raublungenschnecken (Agnatha). 1. Abt. Rhytidae & Enneidae. In: Chemnitz JH, Martini, FHW, von Möllendorff OF (Eds) Systematisches Conchylien Cabinet. Verlag von Bauer & Raspe (Emil Küster), Nürnberg, 59 pp. https://doi.org/10.5962/bhl.title.124018

Laidlaw FF (1932) Notes on Ariophantidae from the Malay Peninsula, with descriptions of new genera. Proceedings of the Malacological Society of London 20: 80–94.

Laidlaw FF (1939) A new Rhiostoma from Malaya. Journal of Conchology 21: 166.

Laidlaw FF (1949) The Malayan species of Diplommatina (Cyclophoridae) Raffles Bulletin of Zoology 19: 199–215.

Lamarck JBPA (1799) Prodrome d’une nouvelle classification des coquilles, comprenant une rédaction appropriée des caractères génériques, et l’établissement d’un grand nombre de genres nouveaux. Mémoires de la Société d’Histoire Naturelle de Paris 1: 63–91.

Liew T-S, Clements R, Schilthuizen M (2008) Sampling micromolluscs in tropical forests: one size does not fit all. Zoosymposia 1: 271–280.

Liew T-S, Vermeulen JJ, Marzuki ME, Schilthuizen M (2014) A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina. Zookeys 393: 1–109. https://doi.org/10.3897/zookeys.393.6717

Liew T-S, Price L, Clements GR (2016) Using Google Earth to improve the management of threatened limestone karst ecosystems in Peninsular Malaysia. Tropical Conservation Science, 9(2): 903–920.

Loosjes FE (1953) Monograph of the Indo-Australian Clausiliidae (Gastropoda, Pulmonata, Clausiliidae, Phaedusinae). Beaufortia 3: 1–221.

Maassen WJM (2000) Notes on the terrestrial molluscs of Sumatra, Indonesia, with descriptions of ten new species (Gastropoda, Prosobranchia & Pulmonata). Basteria 64: 137–150.

Maassen WJM (2001) A preliminary checklist of the non-marine molluscs of West Malaysia. De Kreukel (extra edition 2001), 2001: 1–155.

Ministry of Natural Resources and Environment Malaysia (2016) National Policy on Biological Diversity. Ministry of Natural Resources and Environment Malaysia, Putrajaya, 112 pp.

Metcalfe I (2013) Tectonic evolution of the Malay Peninsula. Journal of Asian Earth Sciences, 76: 195–213. https://doi.org/10.1016/j.jseaes.2012.12.011

Mousson A (1865) Coquilles terrestres et fluviatiles de quelques îles de l'océan Pacifique, receuillis par M. le Dr. Graeffe. Journal de Conchyliologie 13: 164–209.

von Martens E (1860) Die Heliceen, nach natürlicher Verwandtschaft systematisch geordnet, Edition 2. Wilhelm Engelmann, Leipzig, 359 pp. https://doi.org/10.5962/bhl.title.11218

von Martens E (1883) Conchylien von Salanga. Conchologische Mitthelungen als Fortsetzung der Novitates Conchologicae 2: 129–154.

von Martens E (1891) Landschnecken des Indischen Archipels. In: Weber M (Ed.) Ergebnisse einer Reise in Niederländisch Ost-Indien, 209–263. https://doi.org/10.5962/bhl.title.52289

Marzuki ME, Foon JK (2016) A new land snail, Arinia (Notharinia) micro (Caenogastropoda: Cyclophoroidea: Diplommatinidae), from a limestone karst in Perak, Peninsular Malaysia. Raffles Bulletin of Zoology 64: 313–318.

Minerals and Geoscience Department Malaysia (2014) . Industrial Mineral Production Statistics and Directory of Producers in Malaysia 2014. Ministry of Natural Resources and Environment Malaysia. 151 pp.

von Möllendorff OF (1885) Materialien zur Fauna von China. Die Auriculaceen, Nachträge und Berichtungen. Jahrbücher der Deutschen Malakologischen Gesellschaft 12: 349–398.

von Möllendorff OF (1886) The landshells of Perak. Journal of the Asiatic Society of Bengal 55: 299–316.

von Möllendorff OF (1890) Die landschnecken-fauna der Insel Cebu. Bericht der Senckenbergischen Naturfurschenden Gessellschaft, 1889–1890: 189–292. https://doi.org/10.5962/bhl.title.13047

von Möllendorff OF (1891) On the land and freshwater shells of Perak. Proceedings of the Zoological Society of London 1891: 330–348. https://doi.org/10.1111/j.1096-3642.1891.tb01757.x

de Montfort PD (1810) Conchyliogie systematique et classification methodique de coquilles 2. Schoell, Paris, 679 pp. https://doi.org/10.5962/bhl.title.10571

Mörch OAL (1872) Mollusques terrestres et fluviatiles des Iles Nicobar. Journal de conchyliologie 20: 308–327.

de Morgan J (1885a) Quelques espèces nouvelles de mollusques terrestres recueillis dans la peninsula Malaise. Le Naturaliste 7: 68–70.

de Morgan J (1885b) Mollusques terrestes et fiuviatiles de Royaume de Perak et des pais voisins (presque’Ile Malaise). Bulletin de la Société zoologique de France 10: 353–429.

Morse ES (1864) Observations on the terrestrial Pulmonifera of Maine, including a catalogue of all the species of terrestrial and fluviatile mollusca known to inhabit the state. Journal of the Portland Society of Natural History 1: 1–63.

Nevill G (1878) Hand list of Mollusca in the Indian Museum, Calcutta by Geoffrey Nevill. Part I. Gastropoda. Pulmonata and Prosobranchia-Neurobranchia. Office of superintendent of government printing, Calcutta, 338 pp. https://doi.org/10.5962/bhl.title.23978

Panha S, Burch JB (2005) An introduction to the microsnails of Thailand. Malacological Review 37–38: 1–155.

Paton JR (1961) A brief account of the geology of the limestone hills of Malaya. Bull Raffles Mus, 26: 66–75.

Pfeiffer L (1846) Descriptions of twenty new species of Helicea, belonging to the collection of H.Cuming, Esq. Proceedings of the Zoological Society, London, 14: 37–43.

Pfeiffer L (1847) Uebersicht aller bekannten Arten von Cyclostomaceen. Zeitschrift für Malakozoologie 4: 101–112.

Pfeiffer L (1851) Uebersicht der Gattung Pterocyclos Bens. Zeitschrift für Malakozoologie 8: 1–10.

Pfeiffer L (1852) Descriptions of eighteen new species of land shells, from the collection of H. Cuming, Esq. Proceedings of the Zoological Society of London 20: 156–160.

Pfeiffer L (1853) Catalogue of Phaneropneumona or Terrestrial Operculated Mollusca in the Collection of the British Museum. Woodfall & Kinder, London, 324 pp. https://doi.org/10.5962/bhl.title.11482

Pfeiffer L (1854) Descriptions of twenty-three species of Helicea, from the collection of H. Cumning, Esq. Proceedings of the Zoological Society of London 1854: 145–150.

Pfeiffer L (1856) Novitates conchologicae. Series prima. Mollusca extramarina. Beschreiber und Abbildung, neuer oder kritischer Land-und Süsswasser-Mollusken. Theodor Fischer, Casselis, 138 pp. https://doi.org/10.5962/bhl.title.10371

Pfeiffer L (1862) Diagnoses de neuf espèces nouvelles provenant de Siam. Journal de conchyliologie 10: 39–46.

Pilsbry HA (1889) Nomenclature and check-list of North American land shells. Proceedings of the Academy of Natural Sciences Philadelphia 41: 191–210.

Pilsbry HA (1895) Manual of Conchology. Second Series: Pulmonata, Volume 9. Academy of Natural Sciences Philadelphia, 126 pp. https://doi.org/10.5962/bhl.title.6534

Pilsbry HA (1906) Achatinidae: Stenogyrinae and Coeliaxinae. Manual of Conchology series 2, 18: 1–357.

Pilsbry HA (1910) Notes on the classification of the Tornatellinidæ. The Nautilus 23: 122–124.

Pilsbry HA (1916–1918) Pupillidae (Gastrocoptinae). Manual of Conchology 2: 1–371. https://doi.org/10.5962/bhl.title.6534

Pilsbry HA (1939) The land mollusca of North America (north of Mexico). Proceedings of the Academy of Natural Science Philadelphia Monograph no. 3, 1: 1–573.

Potiez VLV, Michaud ALG (1938–1944) Galerie des mollusques, ou Catalogue méthodique, descriptif et raisonné, des mollusques et coquilles du muséum de Douai. J. B. Baillière, Paris, 79 pp. https://doi.org/10.5962/bhl.title.10353

R Core Team (2016) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL http://www.R-project.org/.

Raheem DC, Taylor H, Ablett J, Preece RC, Aravind NA, Naggs F (2014) A Systematic Revision of the Land Snails of the Western Ghats of India. Tropical Natural History, supplement 4: 1–294.

Schilthuizen M (2004) Land snail conservation in Borneo: Limestone outcrops act as arks. Journal of Conchology Special Publication, 3, 149–154.

Seddon MB (2000) Pupisoma orcula. The IUCN Red List of Threatened Species 2000: e.T18919A8698559. https://doi.org/10.2305/IUCN.UK.2000.RLTS.T18919A8698559.en

Semper CG (1873) Reisen im Archipel der Philippinen. Theil 1, Heft 5. Wiesbaden, 213–246.

Simone LRL (2013) Anatomy of predator snail Huttonellabicolor, an invasive species in Amazon rainforest, Brazil (Pulmonata, Streptaxidae). Papéis Avulsos de Zoologia 53: 47–58. https://doi.org/10.1590/S0031-10492013000300001

Siriboon T, Sutcharit C, Naggs F, Rowson B, Panha S (2014) Revision of the carnivorous snail genus Discartemon Pfeiffer, 1856, with description of twelve new species (Pulmonata, Streptaxidae). ZooKeys 401: 45–107. https://doi.org/10.3897/zookeys.401.7075

Solem A (1966) Some non-marine mollusks from Thailand, with notes on classification of the Helicarionidae. Spolia Zoologica Musei Hauniensis 24: 1–110.

Solem A (1988) Non-camaenid land snails of the Kimberley and Northern Territory, Australia. 1. Systematics, affinities and ranges. Invertebrate Taxonomy 2: 455–604. https://doi.org/10.1071/IT9880455

Sowerby GB (1843) Descriptions of new species of shells belonging to the genus Cyclostoma. Proceedings of the Zoological Society of London 11: 59–66.

Stoliczka F (1872) On the land shells of Penang Island, with descriptions of the animals and anatomical notes; part first, Cyclostomacea. Journal of the Asiatic Society of Bengal 41: 261–271.

Stoliczka F (1873) On the land shells of Penang Island, with descriptions of the animals and anatomical notes; part second, Helicacea. Journal of the Asiatic Society of Bengal 42: 11–38.

Sutcharit C, Tongkerd P, Tan SHA, Panha S (2012) Taxonomic revision of Dyakia janus from peninsula Malaysia (Pulmonata: Dyakiidae), with notes on other sinistrally coiled Helicarionoids. The Raffles Bulletin of Zoology 60: 279–287.

Sutcharit C, Naggs F, Wade CM, Fontanilla I, Panha S (2010) The new family Diapheridae, a new species of Diaphera Albers from Thailand, and the position of the Diapheridae within a molecular phylogeny of the Streptaxoidea (Pulmonata: Stylommatophora). Zoological Journal of the Linnean Society 160: 1–16. https://doi.org/10.1111/j.1096-3642.2009.00598.x

Swainson W (1840) A treatise on malacology; or the natural classification of shells and shellfish. Lardner’s Cabinet Cyclopedia. Longman, Orme, Brown, Green & Longmans, London, 419 pp. https://doi.org/10.5962/bhl.title.8027

Sykes ER (1903) On the land operculate Mollusca collected during the “Skeat Expedition” to the Malay Peninsula in 1899–1900. Proceedings of the Zoological Society of London 1903(1): 194–199.

Tan SK, Chan SY, Panha S (2011) A new subspecies of Amphidromus (Amphidromus) atricallosus from Singapore (Mollusca: Gastropoda: Camaenidae). Raffles Bulletin of Zoology 59: 39–46.

Tanmuangpak K, Dumrongrojwattana P, Tumpeesuwan C, Tumpeesuwan S (2015) Sinoennea loeiensis, a new species of diapherid microsnail (Pulmonata: Streptaxoidea: Diapheridae) from Phu Pha Lom-Limestone Hill, Loei Province, northeastern Thailand. Raffles Bulletin of Zoology 63: 293–300.

Thiele J (1931) Handbuch der systematischen Weichtierkunde. Erster Band. Theodor Fischer, Jena, 778 pp. https://doi.org/10.5962/bhl.title.46349

Tomlin JR (1930) Some preoccupied generic names. Proceedings of the Malacological Society of London 19: 22–24.

Tomlin JRB (1938) New Malay land shells. Journal of Conchology 21: 73–75.

Tomlin JRB (1939) New land shells from the Malay Peninsula. Journal of Conchology 21: 146–147.

Tomlin JRB (1941) New land shells from the Malay Peninsula. Journal of Conchology 21: 319–320.

Troschel FH (1857) . Das Gebiss der Schnecken zur begründung einer natürlichen Classification, vol. 1. Nicolaische Verlagsbuchhandlung, Berlin, 252 pp. https://doi.org/10.5962/bhl.title.11262

Tumpeesuwan S, Panha S (2008) First Record of the Genus Schistoloma Kobelt, 1902 (Prosobranchia: Pupinidae) in Thailand. The Natural History Journal of Chulalongkorn University 8: 65–67.

Venmans LAWC (1956) Notes on Alycaeus. Proceedings of the Malacological Society of London 32(8): 81–87.

Vermeulen JJ (1994) Notes on the non-marine molluscs of the island of Borneo. 6. The genus Opisthostoma (GastropodaProsobranchia: Diplommatinidae), part 2. Basteria 58: 73–191.

Vermeulen JJ, Whitten AJ (1998) Fauna Malesiana Guide to the Land Snails of Bali. Backhuys, Leiden, 164 pp.

Vermeulen JJ, Phung LC, Truong QT (2007) New species of terrestrial molluscs (Caenogastropoda, Pupinidae & Pulmonata, Vertiginidae) of the Hon Chong - Ha Tien limestone hills, Southern Vietnam. Basteria 71: 81–92.

Vermeulen JJ, Clements R (2008) Another twist in the tale: a new species of Opisthostoma (Gastropoda, Diplommatinidae) from Peninsular Malaysia. Basteria 72: 263–266.

Vermeulen JJ, Marzuki ME (2014) ‘Charopa lafargei’ (Gastropoda, Pulmonata, Charopidae), a new, presumed narrowly endemic species from Peninsular Malaysia. Basteria 78: 31–34.

Vermeulen JJ, Liew TS, Schilthuizen M (2015) Additions to the knowledge of the land snails of Sabah (Malaysia, Borneo), including 48 new species. ZooKeys 531: 1–139. https://doi.org/10.3897/zookeys.531.6097

Vignard M (1829) Description du Maillotin (Pupina), nouveau genre de coquilles. Annales des Sciences Naturelles 18: 439–440.

de Winter AJ, Cremers HJWN, Soes DM (2009) The Asian tramp snail Bradybaena similaris in a tropical greenhouse in Arnhem, The Netherlands. Basteria 73: 61–64.

Zilch A (1959) Gastropoda Teil 2. Euthyneura. Handbuch der Paläozoologie Band 6, 2: 201–400.

Supplementary materials

Supplementary material 1

Sample completeness curve for all the seven limestone hills sampled in our study.

Junn Kitt Foon, Gopalasamy Reuben Clements, Thor-Seng Liew

Data type: Text and figures in Microsoft Word file.

Explanation note: Data and figure outputs from species richness and sampling completeness analysis.

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

Download file (520.19 kb)

Supplementary material 2

Data matrix for absence/presence of 122 land snail species at 12 limestone hills.

Junn Kitt Foon, Gopalasamy Reuben Clements, Thor-Seng Liew

Data type: Microsoft Excel datasheet.

Explanation note: Data matrix for absence/presence of 122 land snail species at 12 limestone hills.

Download file (7.73 kb)

Supplementary material 3

Location of sampling plots for each of the seven hills sampled in our study.

Junn Kitt Foon, Gopalasamy Reuben Clements, Thor-Seng Liew

Data type: Text in Microsoft Word file.

Explanation note: A list of the location names and coordinates of sampling plots for each of the seven hills sampled in our study.

Download file (13.32 kb)