Acanthonyx formosa, a new species of spider crab (Decapoda, Brachyura, Majidae) from seaweed beds in Taiwan

A new species of spider crab, Acanthonyx formosa, is described from seaweed beds in Taiwan. The species is allied to A. euryseroche Griffin & Tranter, 1986, from western Australia, but differs markedly in the proportions of t he adult male rostrum, and in the structure of the hepatic tooth, the third maxilliped, the adult male chela, and the male first pleopod. Acanthonyx f ormosa is only the second species of Acanthonyx known from the Pacific, the other being A. simplex Dana, 1852, from Hawaii.