Pycnoplax meridionalis ( Rathbun, 1923 )

Ahyong, Shane T., 2008, Deepwater crabs from seamounts and chemosynthetic habitats off eastern New Zealand (Crustacea: Decapoda: Brachyura), Zootaxa 1708 (1), pp. 1-72 : 33-34

Pycnoplax meridionalis ( Rathbun, 1923)

( Figs 15A , 29A )

Carcinoplax meridionalis Rathbun, 1923: 99 , pl. 18 [type locality: 28 km SE of Rame Head, Victoria, Australia]. — Griffin 1972: 84. — Griffin & Brown 1976: 255. — Poore et al. 1998: 68, 72. — Davie 2002: 194. — Poore 2004: 436, fig. 140c, pl. 24a.

Carcinoplax sp. — Clark & O’Shea 2001: 15.

Pycnoplax meridionalis . — Castro 2007: 661 , 663, 669–671 [part, excluding Banks Peninsula specimens = P. victoriensis ( Rathbun, 1923) ].

Material examined. Rumble III Seamount: NIWA 27544 , 4 males (cl 9.1–14.5 mm), 35°44.38–44.29’S, 178°29.83–29.53’E, 382– 207 m, hydrothermal vent, TAN0107/002, 19 May 2001 ; NIWA 27546 , 1 female (cl 8.1 mm), 35°44.38–44.35’S, 178°29.85–29.44’E, 420– 220 m, hydrothermal vent, TAN0107/005, 19 May 2001 ; NIWA 27554 , 2 males (cl 5.9–9.2 mm), 35°44.31–43.95’S, 178°29.79–29.38’E, 939– 300 m, TAN0107/ 122, 20 May 2001 ; NIWA 27545 , 1 male (cl 13.4 mm), 35°44.26–44.37’S, 178°30.45–29.71’E, 1045– 500 m, TAN0107/223, 23 May 2001 ; NIWA 27542 , 4 males (cl 4.2–10.2 mm), 12 females (cl 3.8–11.0 mm), 35°44.35–44.23’S, 178°29.74–29.53’E, 500– 200 m, TAN0107/224, 23 May 2001 .

Rumble V Seamount : NIWA 27543 , 3 males (cl 11.9–13.8 mm), 2 females (cl 6.9–10.2 mm), 36°08.35– 08.32’S, 178°11.55–11.32’E, 440– 370 m, TAN0107/229, 2 May 2001 ; NIWA 27555 , 1 female (cl 11.4 mm), 36°08.29–08.67’S, 178°11.74–11.71’E, 730– 470 m, TAN0107/324, 2 May 2001 .

Off White Island: NIWA 34868 , 1 male (cl 12.0 mm), 37°28.15–28.09’S, 177°06.70–06.57’E, 250–310 m, KAH9907/48, 5 Jun 1999 .

Mahina Knoll: NIWA 6643 , 5 males (7.3–13.2 mm), 4 females (cl 7.0– 9.4 mm), 37°21.34–21.29’S, 177°05.98–06.22’E, 260–280 m, TAN0413/130, 14 Nov 2004 .

Main Knoll: NIWA 29658 , 1 male (cl 20.9 mm), 43°31.85’S, 179°37.75’W, 378–390 m, TAN0604/110, 7 Jun 2006 .

Remarks. Castro (2007) recently transferred Carcinoplax meridionalis to a new genus, Pycnoplax . Two species of Pycnoplax are known from New Zealand waters, both described by Rathbun (1923) in from southeastern Australia: P. meridionalis and P. victoriensis . Both species closely resemble each other, with P.merdionalis readily distinguished by the anteriorly recurved, rather than anterolaterally directed, second anterolateral carapace tooth, and in having the cheliped fingers entirely darkly pigmented ( Figs 15A , 29A ), or pigmented for the distal half or more in small females. The cheliped fingers of P. victoriensis are unpigmented, or at most, light brown at the tips ( Figs 15B , 29B ).

Pycnoplax merdionalis was collected together with Mathildella mclayi sp. nov. on Mahina Knoll. Several specimens were collected from active hydrothermal vents sites (NIWA 27544, 27546), the first records for the species from such habitats.

Distribution. Southern Australia (including Tasmanian seamounts) and New Zealand, from seamounts in Bay of Plenty and on the southern Kermadec Ridge; 126–1045 m ( Rathbun 1923; this study).

Figures

FIGURE 15. A, Pycnoplax meridionalis (Rathbun, 1923), male, cl 13.2 mm (NIWA 6643). B, Pycnoplax victoriensis (Rathbun, 1923), female, cl 10.5 mm (NIWA 29349). C–G, Intesius richeri Crosnier & Ng, 2004, female, cl 15.5 mm (NIWA 27549). C, carapace. D, ventral. E, right chela. F, right cheliped carpus. G, right cheliped merus and carpus.

FIGURE 29. A, Pycnoplax meridionalis (Rathbun, 1923), male, cl 20.9 mm (NIWA 29658). B, Pycnoplax victoriensis (Rathbun, 1923), male, cl 10.4 mm (NIWA 6736). C, Mathildella mclayi sp. nov., female paratype, cl 11.9 mm (NIWA 6769). D, Neopilumnoplax nieli sp. nov., male paratype, cl 15.0 mm (NIWA 29651). E, Miersiella haswelli (Miers, 1886), male, cl 7.8 mm (NIWA 6760). F, Miersiella haswelli (Miers, 1886), ovigerous female, cl 7.1 mm (NIWA 6760). Photo credits: C. Marriot (A, D), R. Stewart (B–C, E–F).