Non-native mollusc species in Brazil: a first national inventory and distributional overview

Biological invasions are among the leading drivers of global biodiversity loss, yet in Brazil, the diversity and impacts of non-native invertebrates remain poorly documented, mostly focusing on fishes, arthropods, and mammals. Here, we present the first comprehensive inventory of non-native molluscs in Brazil, revealing a more than 200% increase—from 26 to 82 species—over the past 15 years. This updated list includes representatives of Gastropoda and Bivalvia, and, for the first time, Polyplacophora and Cephalopoda. Each species was categorized according to introduction status: contained, detected, established, invasive, or data deficient; cryptogenic species were listed separately. In total, 82 non-native and 13 cryptogenic species were listed. Among the former, 12 species are contained, 18 detected, 20 established, 20 invasive, and 12 data deficient. These species are divided unevenly across environments: marine/estuarine (32 non-native, 4 cryptogenic), freshwater (17 non-native), and terrestrial (33 non-native, 9 cryptogenic). Our findings underscore the accelerating rate of non-native mollusc introductions, persistent taxonomic and ecological knowledge gaps, and the urgent need to strengthen biosecurity measures, early detection efforts, and long-term monitoring programs across all environments, as well as properly defining the quality and extent of impacts if present.