LAND SNAILS

Gastropods show high diversifi cation of shell shapes and sculptures. In the tropics, gastropods could be encountered in a variety of habitats. Taxonomically, gastropods are classifi ed in the phylum Mollusca, and have been estimated to contribute approximately 80% of the total species richness. In general, terrestrial gastropods come in three forms: (1) shelled snails, the constructed shell is used to accommodate the soft body; (2) reduced shell, known as semi-slugs, with visible external shell but not large enough for the soft body to fi t in, or with internal minute shell which is not visible to the naked eye, and (3) true slugs, or those that have no shells

New Diplommatinidae from Sarawak, Malaysia (Borneo), of the genera Opisthostoma W.T. & H.F. Blandford, 1860 and Plectostoma H. Adams, 1865 (Gastropoda: Architaenioglossa: Diplommatinidae)

Six new species of the genera Opisthostoma W.T. & H.F. Blandford, 1860 and Plectostoma H. Adams, 1865 (Architaenioglossa, Diplommatinidae) are described from Sarawak (Malaysia), on the island of Borneo

Land snails and slugs of Bau limestone hills, Sarawak (Malaysia, Borneo), with the descriptions of13 new species

"is study presents a list of land snails and slugs found on limestone hills in the District of Bau, the state of Sarawak in Malaysian Borneo. Systematic and random sampling for land snails was conducted at eight limestone outcrops, namely, Gunung Stulang, Padang Pan, Gunung Kapor, Gunung Lobang Angin, Gunung Doya, Gunung Batu, Bukit Sekunyit and Gunung Sebayat. A total of 122 land snail species was documented with photographs of each species. Of the 122 species collected, 13 are new to science, namely, Acmella bauensissp. nov., Japonia bauensissp. nov., Plectostoma margaretchanaesp. nov., Micro-cystina arabiisp. nov., Microcystina atonisp. nov., Microcystina paripari sp. nov., Microcystina liratasp. nov., Microcystina oswaldbrakenisp. nov., Microcystina kilatsp. nov., Philalanka jambusanensissp. nov., Everettia microrhytidasp. nov., Everettia minutasp. nov., and Paralaoma sarawakensissp. nov

The land snail fauna of Batu Kudik, isolated limestone outcrop near Simunjan, Sarawak, Malaysian Borneo (Mollusca, Gastropoda)

The present study provides a checklist of land snails collected from Batu Kudik, a small and isolated limestone outcrop in Simunjan, Sarawak. A total of 24 species of land snails, representing 18 genera and 14 families were recorded, including one newly-described subspecies. The most species-rich of the families in Batu Kudik are Diplommatinidae (17%) and Chronidae (17%) with four recorded species from each of the families. Based on our analysis, Plectostoma wallacei kudikense subsp. nov., Opisthostoma javanica and Georissa pyrrhoderma were identified as the most abundant land snails at this isolated outcrop, whereas Diplommatina onyx and Everettia minuta were recorded as the least abundant. All of the land snails at Batu Kudik were exclusively found sheltered between limestone boulders, underscoring the critical role of this outcrop as their refuge for survival. Consequently, conserving this biodiversity-rich limestone area becomes paramount to prevent the local extinction of these land snail species and possibly other organisms that depend on the unique attributes of the limestone for their survival. We also provide detailed descriptions of Plectostoma wallacei kudikense, a new subspecies of the genus Plectostoma which is endemic to Batu Kudik.A description of a new subspecies Plectostoma wallacei kudikense subsp. nov

Molecular phylogenetics and evolutionary history of the endemic land snail genus Everettia in northern Borneo

Borneo has gone through dramatic changes in geology and topography from the early Eocene until the early Pliocene and experienced climatic cycling during the Pleistocene. However, how these changes have shaped the present-day patterns of high diversity and complex distribution are still poorly understood. In this study, we use integrative approaches by estimating phylogenetic relationships, divergence time, and current and past niche suitability for the Bornean endemic land snail genus Everettia to provide additional insight into the evolutionary history of this genus in northern Borneo in the light of the geological vicariance events and climatic fluctuations in the Pleistocene. Our results show that northern Borneo Everettia species belong to two deeply divergent lineages: one contains the species that inhabit high elevation at the central mountain range, while the other contains lowland species. Species diversification in these lineages has taken place before the Pliocene. Climate changes during the Pleistocene did not play a significant role in species diversification but could have shaped contemporary species distribution patterns. Our results also show that the species-rich highland habitats have acted as interglacial refugia for highland species. This study of a relatively sedentary invertebrate supports and enhances the growing understanding of the evolutionary history of Borneo. Species diversification in Everettia is caused by geological vicariance events between the early Miocene and the Pliocene, and the distribution patterns were subsequently determined by climatic fluctuations in the Pleistocene

The Distribution and Ecology of Land Snails (Mollusca: Gastropoda) in Limestone Habitats of Western Sarawak

Species inventories and ecological studies are fundamental tools for assessing the conservation of limestone-associated species such as land snails. Unfortunately, previous inventories of land snail species in the Bau-Serian limestone area lack a systematic checklist with corresponding illustrations for each species. This study aims to investigate the species composition of land snails in the Bau limestone hill clusters in Sarawak, to measure the estimated species richness and sampling effectiveness between live-caught snails and empty snail shells, and finally to investigate the relationships between land snail species and microhabitats. To fill this knowledge gap, systematic and random sampling for land snails were carried out at eight limestone outcrops. All specimens were sorted, identified to species level, and catalogued. Sampling effectiveness between live snails and empty snail shells was determined using cluster-scale completeness ratios for 135 plots. Species completeness analyses were conducted to extrapolate species richness and inventory for different spatial scales. Cluster analyses were conducted to determine the relationship between the species community and assemblages based on the presence, absence, and abundance data of 17 live-caught land snail species. Associations between land snail species and microhabitats sampled were described using the bipartite weighted network. A total of 122 land snail species, of which 18 are new to science, from 58 genera and 24 families, with photographs of each species. The inventory revealed high completeness of sampling for both empty shells and live-taken snails (> 90%) but species diversity is very low for live snails compared to empty snail shells at hill and cluster scales suggesting that some species may have expired locally. Cluster analysis showed that the land snails assemblages do not correspond to different microhabitats, but rather to locality. The limestone area in Bau has a very high degree of endemism due to the low dispersal ability of the land snails. The soil sample appears to have very high species richness, but the species composition contains species from different niches and microhabitats. As the limestone hills in Sarawak are threatened by various habitat degradation activities, further inventories are needed to assess the species richness of land snails in limestone hill clusters to identify and conserve high-priority areas for snail conservation in Sarawak

A new land snail, Arinia (Notharinia) micro (Caenogastropoda: Cyclophoroidea: Diplommatinidae), from a limestone karst in Perak, Peninsular Malaysia

Marzuki, Mohammad Effendi bin, Foon, Junn Kitt (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, DOI: http://doi.org/10.5281/zenodo.535544

A new species of cyclophorid snail (Mollusca: Prosobranchia) from Terengganu, Peninsular Malaysia

A new species of land snail belonging to the family Cyclophoridae is described from a non-karstic hill dipterocarp forest in Peninsular Malaysia. Pearsonia tembatensis new species, differs from other congeners by its wrinkled shell surfaces, glossy top whorls and a short sutural tube just behind the peristome. Based on comparisons with other cyclophorids, we assign this species to the genus Pearsonia—this represents a new record for this genus in Peninsular Malaysia and also extends the southern limit of its distribution on mainland Southeast Asia

A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina

Plectostoma is a micro land snail restricted to limestone outcrops in Southeast Asia. Plectostoma was previously classified as a subgenus of Opisthostoma because of the deviation from regular coiling in many species in both taxa. This paper is the first of a two-part revision of the genus Plectostoma, and includes all non-Borneo species. In the present paper, we examined 214 collection samples of 31 species, and obtained 62 references, 290 pictures, and 155 3D-models of 29 Plectostoma species and 51 COI sequences of 19 species. To work with such a variety of taxonomic data, and then to represent it in an integrated, scaleable and accessible manner, we adopted up-to-date cybertaxonomic tools. All the taxonomic information, such as references, classification, species descriptions, specimen images, genetic data, and distribution data, were tagged and linked with cyber tools and web servers (e.g. Lifedesks, Google Earth, and Barcoding of Life Database). We elevated Plectostoma from subgenus to genus level based on morphological, ecological and genetic evidence. We revised the existing 21 Plectostoma species and described 10 new species, namely, P. dindingensis sp. n., P.mengaburensis sp. n., P. whitteni sp. n., P. kayiani sp. n., P. davisoni sp. n., P. relauensis sp. n., P. kubuensis sp. n., P. tohchinyawi sp. n., P. tenggekensis sp. n., and P. ikanensis sp. n. All the synthesised, semantic-tagged, and linked taxonomic information is made freely and publicly available online

A cybertaxonomic revision of the micro-landsnail genus Plectostoma Adam (Mollusca, Caenogastropoda, Diplommatinidae), from Peninsular Malaysia, Sumatra and Indochina

Plectostoma is a micro land snail restricted to limestone outcrops in Southeast Asia. Plectostoma was previously classified as a subgenus of Opisthostoma because of the deviation from regular coiling in many species in both taxa. This paper is the first of a two-part revision of the genus Plectostoma, and includes all non-Borneo species. In the present paper, we examined 214 collection samples of 31 species, and obtained 62 references, 290 pictures, and 155 3D-models of 29 Plectostoma species and 51 COI sequences of 19 species. To work with such a variety of taxonomic data, and then to represent it in an integrated, scaleable and accessible manner, we adopted up-to-date cybertaxonomic tools. All the taxonomic information, such as references, classification, species descriptions, specimen images, genetic data, and distribution data, were tagged and linked with cyber tools and web servers (e.g. Lifedesks, Google Earth, and Barcoding of Life Database). We elevated Plectostoma from subgenus to genus level based on morphological, ecological and genetic evidence. We revised the existing 21 Plectostoma species and described 10 new species, namely, P. dindingensis sp. n., P.mengaburensis sp. n., P. whitteni sp. n., P. kayiani sp. n., P. davisoni sp. n., P. relauensis sp. n., P. kubuensis sp. n., P. tohchinyawi sp. n., P. tenggekensis sp. n., and P. ikanensis sp. n. All the synthesised, semantic-tagged, and linked taxonomic information is made freely and publicly available online