Gardens’ Bulletin Singapore 70 (Suppl. 1): 109-121. 2018 
doi: 10.26492/gbs70(suppl.l). 2018-06 
109 
Diversity of terrestrial snails and slugs 
in Nee Soon freshwater swamp forest, Singapore 
W.H. Lim 1 - 2 , T.J. Li 1 & Y. Cai 1 
National Biodiversity Centre, National Parks Board, 
1 Cluny Road, 259569 Singapore 
caLyixiong @ nparks. go v. sg 
2 Current address: The Herbarium, National Parks Board, 
1 Cluny Road, 259569 Singapore 
ABSTRACT. Nee Soon freshwater swamp forest is the last remaining primary freshwater 
swamp forest left in Singapore and it contains a rich diversity of native and locally threatened 
fauna. As native terrestrial snails and slugs are poorly studied and understood in Nee Soon 
freshwater swamp forest, an extensive survey was conducted to establish their current status. 
A total of 19 species was recorded, of which one was recorded for Singapore for the first time. 
Amphidromus atricallosus temasek, a recently described subspecies endemic to Singapore, was 
found to be more commonly distributed than previously known from the swamp forest. Results 
also indicate that despite low overall abundance, Nee Soon freshwater swamp forest harbours a 
rich diversity of land snails and slugs. Any future long term changes in climate or topography, 
or short term changes in hydrology, might affect their distribution and diversity. 
Keywords. Land molluscs, Mollusca, species richness 
Introduction 
Nee Soon freshwater swamp forest is one of the most important conservation sites 
in Singapore and contains a significant number of native, endemic and nationally 
threatened flora and fauna (Ng & Lim, 1992; Ng, 1997; Clews et al., 2018). The forest 
is located within the Central Catchment Nature Reserve, bordered by the Upper Seletar 
Reservoir to the north, Seletar Expressway and Old Upper Thomson Road to the east, 
Upper and Lower Peirce Reservoirs to the south, and the southwestern tributary of the 
Upper Seletar Reservoir and the northern-most tributary of the Upper Peirce Reservoir 
to the west (Yeo & Lim, 2011). The forest consists of primary and old secondary 
vegetation, the stream catchment covering an area of approximately 500 hectares. 
To date, a total of 51 terrestrial snail and slug species (and subspecies), 
representing 33 genera in 15 families, have been recorded in Singapore (Ho, 1995; 
Tan & Chan, 2009; Tan & Woo, 2010; Tan et al., 2011; Tan et al., 2012; Tan & Chan, 
2013). Many of these species are considered to be forest dependent, recorded mainly 
in the Singapore Botanic Gardens rain forest, Central Catchment Nature Reserve 
(including Nee Soon freshwater swamp forest) and Bukit Timah Nature Reserve. 
Forest dependent species include Cyclophorus perdix aquila, Cyclotus rostellatus, 
Ditropis cf. koperbergi, Japonia ciliocinctum, Diplommatina nevilli, Microparmarion 
