Some Pycnogonida from Cook Strait, New Zealand, with descriptions of two new species
Nymphon maoriana n.sp. Figs. 1–8
Nymphon maoriana n.sp. Figs. 1–8.
Material: Off Kahu Rocks, Wellington East Coast; "from Kelp holdfast", 20–30 fathoms; 18/10/56; Coll. J. C. Yaldwyn; 3 females, 2 males (1 ovigerous), 1 immature specimen. (One female specimen is the holotype, the others are paratypes.)
Cook Strait, trawled in approximately 40 fathoms; November, 1956. Coll. J. C. Yaldwyn. Two females.
Off D'Urville Island (Western end of Cook Strait): in shell with Eupagurus novaezelandiae Coll. G. M. Thomson; no date; 1 ovigerous male.
Trunk slender, segmented, without spines, lateral processes separated at ends by about their own width, proboscis slightly longer than neck from above, cylindrical, tapering slightly towards tip. Neck short. Ocular tubercle low, rounded above, arises just anterior to first lateral processes; the pigmentation of the eyes appears very variable, they are heavily pigmented in some specimens and barely discernible in others.
Abdomen reaches just beyond the last lateral processes, elevated at an angle of about 30°.
Chelifore scape widening slightly towards the distal end, scape equal in length to chela. immovable finger equal in length to palm, dactylus slightly longer. Immovable finger armed with 24 spinules, dactylus with 38. The only spines on the chela are the single spines at the base of each finger.
Palp of 5 segments, the first the shortest, and the second the longest. In the holotype the proportions are 1:8.2:5:4.2:3.3.
Oviger (holotype-female) terminal claw a little shorter than the tenth segment, and bearing 11 spinules. Total number of denticulate spines 36 (12 + 8 + 8 + 8). Fourth, fifth and sixth segments nearly straight and in the proportion 1.6:2:1. In the male paratypes the fourth, fifth, and sixth segments of the oviger are markedly curved: the effect of this is to twist the oviger like a cork screw.
Third leg very slender, with sparse very fine setae, second coxa longer than the sum of the other two; second tibia the longest joint, almost half as long again as the femur. Tarsus 3/5 the length of the propodus, claw half as long as the propodus, auxiliaries well developed (3/8 length of claw); basal spines of propodus few and feeble (Fig. 3). The femora of the females are much stouter than those of the males.
Measurements (in mm. holotype first followed by male paratype in brackets).
Length proboscis 1.1 (0.8), width of proboscis 0.54 (0.5), total length (tip proboscis to tip of abdomen) 3.8 (3.0), length of cephalon 1.33 (1.1), width of cephalon 1.33 (1.1), length of chelifore scape 1.25 (1.0), width across second lateral processes 1.33 (1.1), length of abdomen 0.58 (0.4).
Third leg: First coxa 0.45 (0.4). second coxa 1.0 (1.3), third coxa 0.45 (0.4), femur 2.5 (2.35). first tibia 3.25 (2.68). second tibia 4.25 (3.15), tarsus 0.75 (0.63). propodus 1.15 (1.1). claw 0.8 (0.16). auxilliaries 0.3 (0.16).
It is with some hesitation that I propose this further addition to the already unwieldy genus Nymphon, but whilst this species has no remarkable features, the combination of the features it possesses seems to separate it from other rather similar species. N. maoriana falls amongst those species placed in "Group I" by Gordon (1932b), and is rather similar to N. subtile Loman, but is distinguished from this species by the closer spacing of the lateral processes and the greater number of spinules on the fingers of the chelae.