Annotated checklist of freshwater molluscs from the largest freshwater lake in Southeast Asia Author Ng, Ting Hui Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore, 2 Conservatory Drive, 117377, Singapore https://orcid.org/0000-0002-5123-0039 Author Jeratthitikul, Ekgachai Animal Systematics and Molecular Ecology Laboratory, Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand https://orcid.org/0000-0002-3477-9548 Author Sutcharit, Chirasak Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand Author Chhuoy, Samol Inland Fisheries Research and Development Institute (IFReDI), Fisheries Administration, No. 86, Norodom Blvd., PO Box 582, Phnom Penh, Cambodia & Wonders of the Mekong Project, c / o IFReDI, No. 86, Norodom Blvd., PO Box 582, Phnom Penh, Cambodia Author Pin, Kakada Wonders of the Mekong Project, c / o IFReDI, No. 86, Norodom Blvd., PO Box 582, Phnom Penh, Cambodia Author Pholyotha, Arthit Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand https://orcid.org/0000-0001-6677-1164 Author Siriwut, Warut Animal Systematics and Molecular Ecology Laboratory, Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand Author Srisonchai, Ruttapon Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand Author Hogan, Zeb S. Wonders of the Mekong Project, c / o IFReDI, No. 86, Norodom Blvd., PO Box 582, Phnom Penh, Cambodia & Department of Biology, University of Nevada, 1664 N. Virginia Street, Reno, NV 89557, USA Author Ngor, Peng Bun Inland Fisheries Research and Development Institute (IFReDI), Fisheries Administration, No. 86, Norodom Blvd., PO Box 582, Phnom Penh, Cambodia & Wonders of the Mekong Project, c / o IFReDI, No. 86, Norodom Blvd., PO Box 582, Phnom Penh, Cambodia https://orcid.org/0000-0002-3659-6577 pengbun.ngor@gmail.com text ZooKeys 2020 958 107 141 http://dx.doi.org/10.3897/zookeys.958.53865 journal article http://dx.doi.org/10.3897/zookeys.958.53865 1313-2970-958-107 AB196008154249D4B23E1892D2191C18 377C3EF18E8951FD9599616E45E03C94 Pila pesmei (Morlet, 1889) Fig. 5B Ampullaria pesmei Morlet, 1899: 185, pl. 8, fig. 2. Type locality: "Phnom-Penh (Cambodge)". Pila pesmei : Brandt 1974 : 51, pl. 5, figs 70, 71. Material examined. ZRC.MOL.015671. Distribution and habitat. Tonle Sap open area (locality no. 38). Remarks. Although Pila pesmei is widely distributed in Eastern and Northeastern Thailand ( Ng et al. in press ), the species does not appear to be as widespread as Pila gracilis in the Tonle Sap basin, especially during the dry season when our surveys were conducted. It is also uncertain if the species is still extant at its type locality of Phnom Penh. Pila pesmei is harvested in abundance from the Tonle Sap Lake in the rainy season, with more than 380 tonnes recorded at five commercial landing sites in Kampong Chhnang Province within one year (as Pila ampullacea (Linneaus, 1758) in Ngor et al. 2016 , 2018d ). Pila pesmei may be confused with Pila gracilis owing to morphological similarity among some populations ( Ng et al. in press ), and further extensive examination of both species in Cambodia would be necessary to resolve the true distribution of both species in the country. The Pila pesmei morph from Tonle Sap Lake have relatively flat spires, compared to those in Thailand ( Ng et al. in press ), and appear to also be found in Southern Vietnam (as Pila erythrochila (Dautzenberg & Fischer, 1905) in Ng et al. 2019 ).