CRYPTIC INVASIONS OF THE CRAB CARCINUS DETECTED BY MOLECULAR PHYLOGEOGRAPHY

Coastal marine ecosystems world-wide are threatened by invasions of no nindigenous species. The ubiquity of marine sibling species identifiab le only by genetic analysis suggests that many invasions are cryptic a nd therefore undetected, causing an underestimation of the actual numb er and impacts of invading species. We test this hypothesis with Europ ean crabs in the genus Carcinus that have invaded five regions globall y. Partial 16S ribosomal RNA gene sequences confirm sibling species st atus of morphologically similar Atlantic C. maenas and Mediterranean C . aestuarii. Based on 16S rRNA haplotypes, crabs from California, New England and Tasmania were all C. maenas. However, we report the crypti c multiple invasion of both species in Japan and South Africa, where o nly C. aestuarii and C. maenas, respectively, were previously recogniz ed.