Ascorhynchus, Bamber, Roger N, 2011

Bamber, Roger N, 2011, The male of Ascorhynchus constrictus Stock, 1997 (Arthropoda: Pycnogonida), with further new records of deep-sea pycnogonids from New Caledonia, the Solomon Islands and Vanuatu, Zootaxa 2787, pp. 55-67 : 58-60

Ascorhynchus sp. nov. A

Fig. 2

Material. New Caledonia: 1Ƥ (MNHN-IU-2007-4733), damaged, station DW2058, 24°40’S 168°49’E, 25 X 2003, depth 591–1032 m, Ride de Norfolk, Banc Introuvable. Lozonet, Samedi & Richer-IRD coll.

Description of female. Integument smooth, glabrous. Trunk ( Fig. 2 A) fully segmented, rounded rugose tubercle on posterior mid-dorsal margin of cephalon and on each of trunk segments two and three, lateral processes without any tubercles; cephalon with extended anterior neck (anterior margin damaged), attachment of ovigers just anterior to first lateral processes; ocular tubercle conspicuous, pointed, eyes absent. Abdomen articulated, slender, about as long as cephalon and exceeding distal margin of coxa 1 of fourth leg, with numerous curved setae which are longer than abdomen width along whole length.

Proboscis and chelifores broken off, missing.

Palp ( Fig. 2 B) 10-articled, article 3 longest, 1.2 times as long as article 5. Oviger ( Fig. 2 C) 10-articled, article 4 longest, article 5 0.9 times as long as article 4, article 6 0.6 times as long as article 5; strigilis with compound spines in four rows on article 7, in three rows on articles 8 to 10 ( Fig. 2 D); terminal claw simple, curved, 0.4 times as long as distal article.

All legs similar; fourth leg ( Fig. 2 E, F) first coxa shorter than third, second coxa just over twice as long as third coxa; femur sparsely setose, three times as long as second coxa; first tibia long and slender, 1.5 times as long as femur, with numerous fine setae along dorsal margin, longer than tibia width in proximal half; second tibia slender, as long as femur, sparsely setose; tarsus one-third as long as third coxa with ventral row of fine spines; propodus four times as long as tarsus (i.e. brevitarsal), with ventral row of fine spines; main claw stout, just longer than tarsus, accessory claws absent.

Measurements of female (mm). Length (anterior of cephalon to posterior of fourth lateral processes) ~ 7 mm; width across second lateral processes 3.53; abdomen 3.6. Third palp article 3.08; fifth palp article 2.63. Fourth leg, first coxa 0.75, second coxa 2.03, third coxa 0.9, femur 6.08, first tibia 9.23, second tibia 6.08, tarsus 0.31, propodus 1.2. claw 0.38.

Remarks. The damage to the anterior of this specimen, and the resulting absence of proboscis or chelifores, precludes complete description and thus naming of this evidently undescribed species, particularly as the number of articles in the chelifore scape is important in the classification of this genus.

There are only three described brevitarsal species of Ascorhynchus with rounded median trunk tubercles but no ornamentation on the lateral processes. A. castelli (Dohrn, 1881) , a shallow-water Mediterranean and western Atlantic species, differs from the present species in having setose tubercles on the first coxae, much less attenuate tibiae, and no pointed spire on the ocular tubercle, inter alia (e.g. Stock, 1974); A. castellioides Stock, 1957 , a shallow-water species from the Gulf of Mexico and the Caribbean ( Stock, 1957), is similarly a compact species with much less attenuate tibiae, and distal palp articles little longer than wide; both are without long curved setae on the abdomen or tibia 1. The present species is perhaps closest to A. melwardi Flynn, 1929 , a shallow-water species from Indonesia, Singapore and eastern Australia, but that species has the ocular tubercle towards the anterior of the cephalon, long setae on the middorsal trunk tubercles, again has much less attenuate tibiae, and is “extremely spinous” ( Flynn, 1929) with fine spines along anterior and posterior margins of the lateral processes.

This specimen, one of the ten Ascorhynchus species now recorded from Melanesian waters, thus clearly represents an undescribed species, but must await the collection of an anteriorly-complete specimen before completion of its description and its naming.

Figures

FIGURE 2. Ascorhynchus sp. nov. A, female: A, trunk, dorsal; B, palp; C, oviger; D, distal oviger article; E, fourth leg; F, distal articles of fourth leg. Scale line = 3 mm for A, B and E, 2 mm for C, 0.3 mm for D, 0.8 mm for F.