Some Pycnogonida from Cook Strait, New Zealand, with descriptions of two new species
Pallenopsis sp. Figs. 20–22
Pallenopsis sp. Figs. 20–22 .
Material: Collection No. VUZ. 85; Stn. CUK. South of Cape Palliser. 41° 47ʹ S; 175° 02ʹ E; 19/4/57; time, 1915–2400 hrs; bottom depth about 800 fathoms; 4 metre cone net towed at about 600 fathoms; 1 juvenile specimen.
Trunk distinctly segmented, without spines or setae, rather slender, lateral processes separated by about half their own diameter; cephalic segment almost equal in length to the other three segments, produced a considerable distance over the base of the proboscis. Height of ocular tubercle equal to the diameter of the tubercle at the base, rounded above, four eyes with a pair of rounded eminences on the dorsal surface. (Fig. 20.)
Proboscis cylindrical, uniform diameter throughout its length.
Abdomen long, fusiform, reaching to the middle of the second coxa of the fourth leg; rises at an angle of 30° from the trunk.
Chelifore short, stout, scape distinctly two segmented, the first slightly shorter than the second, chela at right angles to scape, fingers longer than palm, when closed the slender tips of the fingers cross.
Palp a small papilla between the bases of the chelifore and oviger.
Oviger very small, of five segments, obviously immature.
Third leg long, slender, coxae subequal, femur and first tibia equal and longer than second tibia, tarsus very short, propodus rather bulbous with a lateral row of small spines, no basal spines, terminal claw half as long as propodus. Auxiliary claws absent.
Measurements (in mm). Length proboscis 1.25, width proboscis 0.5, length cephalon 1.2, width cephalon 0.9, total length 2.4, width second lateral process 1.25, length abdomen 0.65.
Third leg: First coxa 0.5, second coxa 0.6, third coxa 0.7, femur 2.0, first tibia 2.0, second tibia 1.5, tarsus and propodus 1.0, claw 0.5.page 7
The specimen is immature, the ovigers consist of only five segments, and the genital apertures appear to be absent. The interest of the specimen lies in the fact that it was taken in a plankton tow net at 600 fathoms. As the net used was of the open type this specimen could have been taken at a lesser depth, but as the water in the vicinity of this station is about 800 fathoms deep there is little likelihood of its being picked up off the bottom. Gordon (1932b) reported an immature specimen of "? Pallenopsis" (= Pallenopsis calcanea Stephensen 1933?) taken in similar circumstances from 850–1100 m in the South Atlantic off the coast of southern Brazil. Similarly, Carpenter (1905) reported an adult of Pallenopsis holti Carpenter = P. tritonis Hoek, taken with a tow net in 382 fathoms off Achill Head, Ireland. Stephensen (1933) and Hedgepeth (1948) both record P. calcanea from tow nettings; the latter author remarks that it is "evidently a bathypelagic species". The present specimen resembles Gordon's and Stephensen's figures of P. calcanea in the presence of a pair of small tubercles on the dorsal surface of the ocular tubercle, but differs from that species in the chelae, legs, and ovigers. This specimen does not appear to be the juvenile of either of the species of this genus so far recorded from New Zealand.