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Aim: Effective control of invasive species and conservation of native biodiversity requires accurate species identification. Several species of apple snails (Ampullariidae: Pomacea) from South America have become widespread pests in Asia since their introduction in the early 1980s, but their taxonomic uncertainty has hindered our understanding of the invasive processes. We aim to determine the identity and distribution of Pomacea species in Hong Kong, which has been known as a stepping stone of species invasion. Location: Hong Kong. Methods: We collected 162 apple snails from five freshwater wetlands of Hong Kong, sequenced the mitochondrial COI, genotyped the nuclear EF1α and built a COI dataset of 1378 sequences of apple snails from mainland China, Malaysia, Argentina and Brazil. We identified the species, determine the introgression pattern and analysed their population structures. Results: We found the co‐occurrence of P. canaliculata, P. maculata and P. occulta in Hong Kong for the first time. Pomacea canaliculata represented the dominant species (85% of collected specimens). The three Pomacea species from Hong Kong had low genetic diversity. High genetic similarity existed between P. canaliculata populations of Hong Kong and Malaysia, P. occulta populations of Hong Kong and mainland China and P. maculata populations of mainland China and Malaysia. Our samples contained a high proportion of hybrids. Main conclusions: Apple snails may have been introduced into Hong Kong multiple times: both P. canaliculata and P. occulta likely came from Argentina; P. maculata came from both Argentina and Brazil. Genetic drift largely explains the differentiation of Pomacea spp. among regions. Introgressive hybridization may have contributed to population fitness by increasing genetic variation to neutralize the founder effect. The knowledge on species identity, distribution and genetic diversity of apple snails from this study will contribute to better understanding their invasive mechanisms and prevention of their continued spread in Asia. [ABSTRACT FROM AUTHOR]

Apple snails from the family Ampullariidae have become economically important due to several species mainly from the genus Pomacea being invasive. The heat shock proteins (HSPs), which are important molecular chaperones for species responding to various stresses, have been proved to play critical roles in adapting harsh environments in the invasive apple snails. The recent release of the genomes of Pomacea canaliculata , Pomacea maculata , Lanistes nyassanus , and Marisa cornuarietis has opened the opportunity for a comprehensive analysis of HSP superfamily in the ampullariids. We identified the number of HSP from P. canaliculata (PcaHSPs) was greater than that from the other three species. A total of 42 PcaHSPs were distributed on 12 chromosomes and were classified into the families of HSP90, HSP70, HSP60, HSP40, HSP20, and HSP10. Each family formed a monophyletic clade on the phylogenetic tree with strong support values, except for the HSP90 and HSP70 families. The RNA-seq data shows that most the PcaHSPs were of tissue-specific expression levels. Moreover, we identified more HSP genes with stronger transcription levels in response to heat than cold stress. Our findings are informative for future studies on stress adaptation and developing effective management strategies focusing on HSPs in invasive apple snails. [ABSTRACT FROM AUTHOR]