Annotated checklist of freshwater molluscs from the largest freshwater lake in Southeast Asia

Abstract

The Tonle Sap Lake in Cambodia is a crucial freshwater biodiversity hotspot and supports one of the world’s largest inland fisheries. Within the Tonle Sap basin, freshwater molluscs provide vital ecosystem services and are among the fauna targetted for commercial harvesting. Despite their importance, freshwater molluscs of the Tonle Sap basin remain poorly studied. The historical literature was reviewed and at least 153 species of freshwater molluscs have been previously recorded from throughout Cambodia, including 33 from the Tonle Sap basin. Surveys of the Tonle Sap Lake and surrounding watershed were also conducted and found 31 species, 15 bivalves (five families) and 16 gastropods (eight families), in the Tonle Sap basin, including three new records for Cambodia (Scaphula minuta, Novaculina siamensis, Wattebledia siamensis), the presence of globally invasive Pomacea maculata and potential pest species like Limnoperna fortunei. This study represents the most comprehensive documentation of freshwater molluscs of the Tonle Sap basin, and voucher specimens deposited at the Inland Fisheries Research and Development Institute, Cambodia, represent the first known reference collection of freshwater molluscs in the country. In order to combat the combined anthropogenic pressures, including invasive species, climate change and dams along the Mekong River, a multi-pronged approach is urgently required to study the biodiversity, ecology, ecosystem functioning of freshwater molluscs and other aquatic fauna in the Tonle Sap basin.

Phylogeography and distribution of the freshwater razor clams Novaculina myanmarensis and N. gangetica in Myanmar, with notes on two doubtful nominal taxa described as Novaculina members (Bivalvia: Pharidae)

“…In its turn, Novaculina gangetica was found to occur in the Dalet River, approximately 80 km SE from the previously known localities in the Kaladan -Lemro Basin, western Myanmar (Bolotov et al 2018a(Bolotov et al , 2018b. Ng et al (2020) recently discovered a population of Novaculina siamensis in the Tonle Sap River (Cambodia). Thus, this species occurs not only in the Mekong Delta and coastal rivers of the Gulf of Thailand (Morlet 1889;Brandt 1974;Sayenko et al 2017;Bolotov et al 2018a) but also in the Lower Mekong as far upstream as the Tonle Sap (approximately 300 km away from the coast).…”

“…Novaculina gangetica is known to occur in similar environments (Bolotov et al 2018a(Bolotov et al , 2018b. Ng et al (2020) also collected Novaculina siamensis from cylindrical holes in clay bottom of the Tonle Sap River.…”

“…The circles indicate records from our earlier work(Bolotov et al 2018a). The stars indicate new occurrences(Ng et al 2020; this study)…”

Echinostoma mekongi: Discovery of Its Metacercarial Stage in Snails, Filopaludina martensi cambodjensis, in Pursat Province, Cambodia

“…The present study first confirmed that F. martensi cambodjensis , a freshwater gastropod species, acts as a second intermediate host for E. mekongi in Pursat Province, Cambodia. This snail species ( F. martensi ) is widely distributed in Indochina Peninsula, including Vietnam, Thailand, and Cambodia [ 4 , 9 – 11 ]. In Pursat Province, Cambodia, nearby the Tonle Sap Lake, these snails are commercially available in street markets together with larger snails, including Pila spp.…”

“…1A ), from a local market in Pursat Province, Cambodia in May 2017. The identification of the snail species and subspecies was performed according to a previous report [ 4 ]; in comparison with Filopaludina martensi martensi , this subspecies is lacking in spiral ridges. The snails were transported to Korea (Department of Parasitology and Tropical Medicine, Gyeongsang National University College of Medicine, Jinju) under ice, and examined for echinostome metacercariae using the artificial digestion method as previously described [ 5 ].…”