Eurynome bituberculata Griffin, 1964

Ahyong, Shane T., 2008, Deepwater crabs from seamounts and chemosynthetic habitats off eastern New Zealand (Crustacea: Decapoda: Brachyura), Zootaxa 1708 (1), pp. 1-72 : 40-42

Eurynome bituberculata Griffin, 1964

( Fig. 18A )

Eurynome bituberculata Griffin, 1964: 197–203 , figs 1–11 [type locality: off Glen Burn, E Wairarapa coast, New Zealand]; 1966: 43–45, figs 6, 7, 20. — Griffin & Tranter 1986: 205–206. — McLay 1988: 102, fig. 21.

Material examined. Off North Cape: NIWA 34931 , 1 ovigerous female (9.6 mm), 34°26.7’S, 173°07.5’E, 113–115 m, F932, 15 Oct 1968 .

Poor Knights Islands: NIWA 34929 , 1 ovigerous female (7.9 mm), 35°30.0’S, 174°43.0’E, 121 m, F75, 12 Nov 1964 .

Tumokemoke Seamount: NIWA 9851 , 1 male (cl 7.4 mm, cw 5.8 mm), 37°28.19–28.15’S, 176°55.15– 54.94’E, 240– 212 m, TAN0413/166, 15 Nov 2004 .

Off Cape Egmont : NIWA 1710 , 1 male paratype (cl 10.5 mm), 39°22’S, 171°50’E, 231–251 m, muddy sand and broken shell, B314, sample 4, 25 Oct 1960 ; NIWA 4233–4236 , 4 male paratypes (cl 8.8–11.5 mm), 39°22’S, 171°50’E, 231–251 m, muddy sand and broken shell, B314, sample 5, 25 Oct 1960 .

N of Cape Farewell : NIWA 34930 , 12 males (cl 9.7–13.6 mm), 6 females (10.1–12.9 mm), 40°16’S, 172°32.29’E, 126–127 m, B686, 28 Oct 1962 .

Remarks. Eurynome bituberculata is a distinctive but seldom reported species, so additional material is reported here to document its known range. The specimen of E. bituberculata from Tumokemoke Seamount, at 7.4 mm cl ( Fig. 18A ), is the smallest recorded to date, and agrees well in most respects with type and other material from northern New Zealand. The hepatic and lateral branchial spines of the 7.4 mm specimen are more pronounced and the margins of the dorsal tubercles are more acutely dentate than in larger specimens, which are differences associated with size. The anteromedial branchial region of E. bituberculata bears a group of four flat tubercles, of which the anterolateral tubercle is produced to a small upright spine in the 7.4 mm specimen — that spine generally becomes reduced or obsolete with increasing size, appearing at most as a small conical projection from the margin of the flattened tubercle. The inner margins of the rostral spines of the 7.4 mm specimen are granular or minutely serrate as in most other specimens. Although, the rostral spines of E. bituberculata were characterised as truncate, they are better described as tapering to a narrow, rounded apex. The slender rostral apices of most specimens are broken, appearing truncate. As reported by Griffin (1964), the chelipeds are significantly sexually dimorphic, up to 3.25 times carapace length in males, and no longer than the carapace in females.

Distribution. Northern New Zealand, from off the Wairarapa coast and Cape Farewell to North Cape; 73– 280 m ( McLay 1988; this study).

Figures

FIGURE 18. A, Eurynome bituberculata Griffin, 1964, male, cl 7.4 mm (NIWA 9851). B, Leptomithrax garricki Griffin, 1966, male, cl 98.0mm (NIWA 6735).