Larval development of the brush-clawed shore crab Hemigrapsus takanoi Asakura & Watanabe, 2005 (Decapoda, Brachyura, Varunidae)

The brush-clawed shore crab Hemigrapsus takanoi is a native species from the Western Pacific and an invader of the European Atlantic coast from northern Spain to southern Denmark. Despite the increasing concern about its rapid expansion, little is known about the early stages in its life history. In the present study, the larval morphology of H. takanoi is described and illustrated from specimens obtained in the laboratory from its type locality, Tokyo Bay, Japan. Its larval development follows the pattern of Varunidae, that involves five zoeae and one megalopa. The morphological characters of the larvae of H. takanoi are compared with those of the other known Hemigrapsus species of the North Pacific. In addition, to facilitate an early detection of the invasive species of Varunidae inhabiting European Atlantic waters, a summary of the key characters to identify their larval stages is included.