Sixty-seven years on the lam: new records of a non-native swimming crab, Charybdis hellerii (A. Milne-Edwards, 1867) (Decapoda: Brachyura: Portunidae), in the Hawaiian Islands.
Over the last thirty years, the Indo-West Pacific swimming crab Charybdis hellerii (A. Milne-Edwards, 1867) (Brachyura, Portunidae) has become an abundant, well-established marine invasive throughout the warmer waters of the Western Atlantic. This aggressive, moderately sized crab is also not native to the Hawaiian Islands; however, a single specimen was collected in 1950 from a vessel in Pearl Harbor that originated from Guam. To our knowledge this species has not since been documented in the Hawaiian Islands. We report the discovery of four adult specimens of C. hellerii from a single locality in Kāne'ohe Bay, O'ahu, including an ovigerous female, raising concern that this species may now be established in Hawai'i. Molecular data (H3, CO1, 16S, and 12S rRNA) reveal that this Hawaiian population is not genetically distinct, but likely originated from a Western Pacific population. Given the invasive potential of this crab, including its preference for habitats occupied by commercially important species, additional surveys should be conducted to determine the extent and consequence of its introduction. A brief guide is provided to distinguish C. hellerii from similar species found in Hawai'i. Examination of the holotype of Charybdis vannamei Ward, 1941 confirms that this taxon is a junior synonym of C. hellerii.