Deepwater crabs from seamounts and chemosynthetic habitats off eastern New Zealand (Crustacea: Decapoda: Brachyura)

Deepwater crabs from seamounts and chemosynthetic habitats off eastern New Zealand are reported. Of the 30 species reported, eight are new to science: Cymonomus clarki sp. nov. (Cymonomidae), Dicranodromia delli sp. nov. (Homolodromiidae), Ethusina castro sp. nov. and E. rowdeni sp. nov. (Dorippidae), Trichopeltarion janetae sp. nov. (Atelecyclidae), Mathildella mclayi (Mathildellidae), Neopilumnoplax nieli sp. nov. (Mathildellidae), and Garthambrus tani sp. nov. (Parthenopidae). The dorippids, parthenopids and mathidellids reported here are the first members of these families to be described from New Zealand. Three previously described species are recorded for the first time from New Zealand waters: Dicranodromia spinulata Guinot, 1995 (Homolodromiidae), Intesius richeri Crosnier & Ng, 2004 (Mathildellidae) and Miersiograpsus australiensis Turkay, 1978 (Plagusiidae). The majority of brachyurans from New Zealand seamounts and chemosynthetic habitats are 'typical' deepwater forms of which thirteen species are presently unique to New Zealand. At species level, 43% of the seamount and cold-seep brachyurans are apparent New Zealand endemics, with strongest affinities with the eastern Australian fauna (37%). At the generic level, however, congeners of most species reported herein occur widely in the Indo-West Pacific (including eastern Australia and New Caledonia), suggesting that the New Zealand seamount and cold-seep brachyuran fauna is an extension of the tropical Indo-West Pacific fauna. Thirty-three percent (10 of 30 species) of the known New Zealand seamount and cold-seep brachyurans have only been recently discovered indicating that species richness is probably strongly underestimated. A key to the Brachyura known from New Zealand seamounts and chemosynthetic habitats is given.