Phoxichilidium alis, Bamber, 2013

Bamber, Roger N., 2013, Deep-water Pycnogonida from recent cruises to Papua New Guinea and Melanesia, with an appendix of new records from Polynesia and descriptions of five new species, Zoosystema 35 (2), pp. 195-214 : 206-208

Phoxichilidium alis n. sp.

( Fig. 4 )

MATERIAL EXAMINED. — 1 ♂, holotype, MNHN- IU-2008-20518, Stn. CP3761, Vicinity of the Feni Islands, Papua New Guinea, 03°59’S, 153°56’E, 760-823 m, 14.XI.2010, coll. Samadi & Corbari.

ETYMOLOGY. — Named after the research vessel responsible for its collection (noun in apposition).

DESCRIPTION OF MALE HOLOTYPE

Body ( Fig. 4A ) length: 4.35 mm.Trunk completely segmented, glabrous; cephalon 40% of total length; low, rounded ocular tubercle, with indication of eyes (in preserved material). Lateral processes without tubercles, separated by about half their own diameter. Abdomen tip reaching just past distal margin of fourth lateral processes.

Proboscis stout, cylindrical, 0.45 times as long as trunk.

Chelifore scape of one article, overreaching proboscis; chela ( Fig. 4B ) relatively slender, fingers without any teeth or spines.

Oviger ( Fig. 4C ) of six articles, proximal article short, glabrous; second article 1.4 times as long as first, with fine ventrodistal seta; third article longest, 2.6 times as long as second article, with slight proximal constriction and sparse marginal setae; fourth to sixth articles curved; fourth article 0.7 times as long as third article, with marginal setae along distal two-thirds of dorsal margin; fifth article 0.6 times as long as fourth article, with sparse proximally-directed setae; sixth article small, subtriangular, apparently naked.

Third leg ( Fig. 4D, E ), first coxa about as long as lateral process, without tubercles; second coxa nearly twice as long as first coxa, with slight ventrodistal genital spur; third coxa just longer than first coxa; femur 2.7 times as long as second coxa, with undulating margins and dorsoproximal cementgland pore, distally with small tubercle bearing seta; first tibia 0.8 times as long as femur, dorsal margin undulating, ventral margin with sparse fine setae; second tibia longest, 1.4 times as long as first tibia, dorsal margin undulating with spinules, ventral margin with dense fine setae; tarsus ( Fig. 4E ) short, 0.2 times as long as propodus, dorsodistal tubercle and whole ventral margin with short spinules; propodus 0.4 times as long as second tibia, dorsal margin and sole armed with fine spinules, heel with two short, blunt spines; main claw stout, 0.35 times as long as propodus; auxiliary claws fine, mounted dorsally, 0.2 times as long as main claw.

Female unknown.

Measurements of holotype (mm): trunk length 4.35; width across second lateral processes 2.4; proboscis length 2.0; abdomen length 0.65. Chelifore scape length 2.1.

Oviger article 1 (O1) 0.4; O2 0.53; O3 1.4; O4 1.0; O5 0.6; O6 0.3.

Third leg: coxa-1 0.65, coxa-2 1.24, coxa-3 0.76, femur 3.4, tibia-1 2.7, tibia-2 3.7, tarsus 0.24, propodus 1.4, main claw 0.5, auxiliary claw 0.1.

REMARKS

Two species of Phoxichilidium have been described previously from Melanesia ( New Caledonia), both by Stock (1991), but Phoxichilidium alis n. sp. agrees with neither Phoxichilidium forfex Stock, 1991 nor Phoxichilidium tuberculatum Stock, 1991 because it has no teeth on the chela fingers, the lateral processes are separated by less than their own width, and the third oviger article is substantially larger than the second (three-times as long, compared with subequal in the other two).

Of the ten previously-described Phoxichilidium species , only five are without teeth on the chela fingers, and in three of those – Phoxichilidium femoratum (Rathke, 1799) , Phoxichilidium quadradentatum Hilton, 1942 (probably a junior synonym of P. femoratum ) and Phoxichilidium ungellatum Hedgpeth, 1949 – the lateral processes are separated by more than their own width (only half their own width in P. alis n. sp.). Of the remaining two species, Phoxichilidium micropalpidum Hilton, 1942 has auxiliary claws between 0.35 and 0.5 times as long as the main claw (0.18 times in P. alis n. sp.), while Phoxichilidium tuberungum Turpaeva, 2006 has no auxiliary claws and a third oviger article 1.5 times as long as the second; both of these species have four pointed heel spines on the propodus of the walking leg (two blunt spines in P. alis n. sp.).

Phoxichilidium alis n. sp. is another deep-water species of this conservative genus to have eyes, as are the other two Melanesian species (see above), albeit unpigmented in this preserved material.

Family PYCNOGONIDAE Wilson, 1878

Figures

FIG. 4.— Phoxichilidium alis n. sp., male holotype (MNHN-IU-2008-20518):A, habitus,dorsal;B, chela; C, oviger;D, third leg;E, distal article sof third leg. Scale bar: A, D, 2 mm; B, 0.5 mm; C, 1 mm; E, 0.3 mm.