Dorhynchus ramusculus ( Baker, 1906 )

Published, First, 2009, New records of crabs (Decapoda: Brachyura) from the New Zealand region, including a new species of Rochinia A. Milne-Edwards, 1875 (Majidae), and a revision of the genus Dromia Weber, 1795 (Dromiidae), Zootaxa 2111, pp. 1-66 : 26-29

Dorhynchus ramusculus ( Baker, 1906)

( Figs. 10a, b)

Stenorhynchus ramusculus Baker, 1906: 104 , pl. 1 figs 1, 1a.

Achaeopsis ramusculus — Hale 1927: 124, fig. 121. — Griffin 1966: 35, fig. 4. — Griffin & Tranter 1986a: 21; 1986b: 352. — McLay 1988: 116, fig. 25a–d.

Dorhynchus ramusculus — Davie 2002: 293. — Ahyong 2008: 36 , figs. 16B, C

Material Examined. Chatham Rise: 1 male, 11.9 mm x 19.7 mm, another similarly-sized male too damaged to measure, 42°45.93’S, 179°59.34’W, 875– 757 m, Tangaroa , stn TAN0104/02, 15 Apr. 2001 ( NIWA 48576); 1 ovigerous female, 10.1 mm x 15.2 mm, 42°47.17’S, 179°59.11’W, 993– 900 m, Tangaroa, TAN 0104/48, 16 Apr. 2001 ( NIWA 48570).

Remarks. The genera Dorhynchus Thomson, 1873 and Achaeopsis Stimpson, 1857 have had a complex history that has been summarized by Griffin (1966), Manning & Holthuis (1981) and Davie (2002). The species has been known until now New Zealand as Achaeopsis ramusculus following the arguments put forward by Griffin (1966). However, Manning & Holthuis (1981) argued that the two genera should not be synonymised as had been proposed by Griffin (1966). Following Davie (2002) the species should now be known as Dorhynchus ramusculus .

Dorhynchus ramusculus is most likely to be confused with Achaeus curvirostris (A. Milne Edwards, 1873) , A. akanensis Sakai, 1937 , and A. kermadecensis Webber & Takeda, 2005 , but they are easily separated because they lack the long, divergent rostral spines.

Distribution. Dorhynchus ramusculus is restricted to New Zealand and Australia (from Western Australia to New South Wales). Its reported depth range is 150–740 m, but it should be noted that the specimens examined here are from 757–993 m, extending the lower depth limit. The species is now reliably known from 140– 993 m. Its southern limit now extends to the Chatham Rise, 42°47’S.