First record of the swimming crab Charybdis ( Archias ) hoplites (Wood-Mason, 1877) (Portunidae) in the Atlantic

Abstract Portunid crabs of the genus Charybdis De Haan, 1833 are among the most frequently reported marine invaders worldwide. Here, we report the first record of Charybdis ( Archias ) hoplites (Wood-Mason, 1877) outside its native Indo-West Pacific range, collected from the Test Estuary, Southampton Water, United Kingdom. Morphological and molecular analyses confirm the specimen’s identity and clarify diagnostic features useful for distinguishing C . ( A. ) hoplites from closely related taxa. This represents the northernmost record of any Charybdis species and suggests a long-distance dispersal event, associated with shipping activities in the Port of Southampton. Environmental data indicate that salinity and turbidity at the collection site are within known tolerances for Charybdis spp., although low winter temperatures may limit survival and establishment. The detection of this warm-water species in a major international port highlights the ongoing need to monitor non-native marine fauna.