Cilunculus roni, 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 : 202-206

Cilunculus roni n. sp.

( Figs 2 ; 3 )

HOLOTYPE.— 1♂, MNHN-IU-2011-2583, Stn.DW 3696, NE Manus Island , Papua New Guinea, 01°54’S, 147°12’E, 326-355 m, 30.XI.2010, coll. Samadi & Corbari.

ETYMOLOGY. — Named after Roni Robbins of Artoo, in gratitude for unparalleled collaboration (noun in apposition).

DESCRIPTION OF MALE HOLOTYPE

Body( Fig. 2A, B ) length 4.25 mm.Trunk completely segmented, posterior margins of trunk segments flared.Cephalon 28%of total length, flared anteriorly into a typical hood; frontal margin extended into two pointed tubercles (“horns”), with pointed mid-dorsal tubercle at posterior margin, lateral processes with posterodistal spine-tipped tubercle; tall, rounded ocular tubercle above attachment of ovigers, with indication of eyes (in preserved material). Second trunk segment with mid-dorsal tubercle at posterior margin, lateral processes with posterodistal spine-tipped tubercle and smaller mid- posterior pointed tubercles, dorsodistally with long, slender seta; third trunk segment with mid-dorsal tubercle at posterior margin, lateral processes with or without mid-posterior pointed tubercles. Fourth trunk segment without tubercles. Lateral processes separated by about half their own diameter. Oviger implantation below first lateral processes. Abdomen not articulated at base, its tip reaching distal margin of second coxa of fourth leg, raised dorso-subdistally and bearing two longer setae and two fine spinules.

Proboscis held ventrally, stout, cylindrical, with two dorsal triangular processes (tubercles) in proximal third, 0.9 times as long as trunk.

Chelifore scape of one article, distally flared; chela totally atrophied.

Palp ( Fig. 2D ) of eight articles; article 2 longest, almost twice as long as article 4; article 4 with fine setae along distal two-thirds of dorsal margin; article 5 very short, articles 6 to eight elongate, slender; distal four articles each with dense row of ventral setae.

Oviger ( Fig. 3A, B ) proximal article short, glabrous; article 2 longest, with sparse marginal setae; article 3 about 0.2 times as long as article 2, with ventrodistal setae; articles 4 to 7 with denser marginal setae; article 4 half as long as article 2, article 5 0.6 times as long as article 4, article 6 half as long as article 5, article 7 as long as article 6; article 8 with five, article 9 with one and article 10 with two ventral compound spines.

Third leg ( Fig. 3 C-F), first coxa shorter than lateral process, armed distally with four spinetipped tubercles; second coxa 1.5 times as long as first coxa, with conspicuous ventrodistal genital spur; third coxa just shorter than first coxa, with setose ventrodistal tubercle; femur 2.9 times as long as second coxa, with tall, conical cementgland tube distal of mid-length, four tubercles around femur proximal to cement-gland tube, each bearing slender seta ( Fig. 3D ), distally with array of five seta-bearing tubercles ( Fig. 3E ); first tibia 1.2 times as long as femur, with two pairs of dorsal seta-bearing tubercles around mid-length and three such tubercles dorsodistally; second tibia 1.1 times as long as first tibia, with sparse dorsal setae; tarsus short, 0.2 times as long as propodus, with raised “hump” dorsally, ventral margin with fine setae and distal spine; propodus one quarter length of second tibia, with dorsal hump at onethird of length and much smaller dorsal swelling at two thirds of length, ventrally with four robust spines interspersed with setae; main claw stout, 0.4 times as long as propodus; auxiliary claws fine, one third length of main claw.

Cement gland tubes present on all legs, genital spurs on coxa 2 only present on third and fourth legs.

Female unknown.

Measurements of holotype (mm): trunk length 4.25; width across second lateral processes 3.3; proboscis length 4.0; abdomen length 1.42. Chelifore scape length 0.9.

Palp article 2 (Pa2) 2.0; Pa3 0.22; Pa4 1.1; Pa5 0.3; Pa6 0.8; Pa7 0.6; Pa8 1.0.

Oviger article 1 (O1) 0.3; O2 2.2; O3 0.5; O4 1.1; O5 0.75; O6 0.35; O7 0.35; O8 0.22; O9 0.2; O10 0.1.

Third leg: coxa-1 0.8, coxa-2 1.2, coxa-3 0.75, femur 3.4, tibia-1 4.1, tibia-2 4.5, tarsus 0.25, propodus 1.1, main claw 0.5, auxiliary claw 0.16.

REMARKS

With a cephalic “hood” within which the anterior appendages arise, few compound spines on the distal oviger articles, and its general conformation, the present species is clearly a member of the genus Cilunculus . However, Cilunculus roni n. sp. is unique in the genus in having an eight-articled palp, with three slender distal articles: nine palp articles, including four short distal articles, is the norm for the genus. Additional unique features are the proximal tubercles on the proboscis, and the single long dorsodistal seta on each second lateral process.

Stock (1997) gave a key to the species of Cilunculus then known, in which the present species would key out as Cilunculus frontosus Loman, 1908 , but that species is without any tubercles on the trunk or on the leg articles. Since then, only four further species have been described, three of these from Melanesia. Cilunculus ateuchus Bamber, 2004 , from New Caledonia ( Bamber 2004a), is distinct from the present species in being glabrous, with naked tubercles on the lateral processes and first coxa, no other tubercles on the leg articles, and no dorsal swelling on the propodus. Cilunculus cymobostrichos Bamber, 2004 and Cilunculus mergus Bamber, 2004 , both from the Solomon Islands ( Bamber 2004b), and Cilunculus misesetosus Turpaeva, 2005 (probably a junior synonym of Cilunculus europaeus Stock, 1978 ), from the North Atlantic ( Turpaeva 2005), are all without any tubercles on the trunk midline or on the lateral processes or leg articles, or on the anterior margin of the cephalon, unlike C. roni n. sp.

Cilunculus roni n. sp. shares only with C. scaurus Stock, 1997 and C. mergus Bamber, 2004 the pres- ence of a dorsal swelling (“hump”) on the propodus of the walking legs, although only C. roni n. sp. has a dorsal tubercle on the tarsus as well. Cilunculus scaurus , as C. mergus , has no dorsal tubercles on the trunk midline, and both have a two-articled chelifore scape, unlike the present species.

The deep waters around Melanesia harbour a remarkable diversity of Cilunculus species , ten having been recorded previously ( Bamber 2004b). Cilunculus roni n. sp. is the first to have been recorded from around Papua New Guinea.

Family PALLENOPSIDAE Fry, 1978

Figures

FIG. 2.— Cilunculus roni n. sp.,male holotype (MNHN-IU-2011-2583):A, habitus,lateral;B, habitus,dorsal;C, cephalon and proboscis, antero-ventral view; D, palp. Scale bar: A-C, 3 mm, D, 2 mm.

FIG. 3. — Cilunculus roni n. sp., male holotype (MNHN-IU-2011-2583) A, oviger; B, distal three oviger articles; C, third leg; D, diagram- matic section of femur proximal to cement-gland tube; E, distal tip of femur; F, distal leg articles. Scale bar: A, 2 mm; B, 0.3 mm; C-E, 3 mm; F, 0.8 mm.