A new invasive freshwater mussel: Discovery of a non-native population of Pilsbryoconcha exilis (Lea, 1838) in Myanmar (Bivalvia: Unionidae)

The present study reports on the first record of a non-native population of the freshwater mussel Pilsbryoconcha exilis (Lea, 1838) (Bivalvia: Unionidae) in Myanmar. It was discovered from irrigation canals that are situated in the Delta Region of the Ayeyarwady River. Based on approximate age estimates and information from local villagers, this population was probably established in 2019-2020. The DNA sequence data reveals that the Ayeyarwady population shares a single COI haplotype and that this haplotype was previously recorded from the Udon Thani Province of Thailand (Mekong River drainage). Based on this evidence, we could assume that P. exilis was introduced to Myanmar from Thailand. Our new findings expand the global checklist of invasive freshwater mussels that currently contains 17 species.