Paranymphon bifilarium, Arango, Claudia P., 2009

Arango, Claudia P., 2009, New species and new records of sea spiders (Arthropoda: Pycnogonida) from deep waters in Western Australia, Zootaxa 1977, pp. 1-20 : 13-15

Paranymphon bifilarium n. sp.

( Figures 6 , 8 C)

Holotype: AM P72806, 1 male with eggs and protonymphs. 9 December 2005, Ningaloo South, CSIRO station 141-142, collected with beam trawl from 22.0743°S 113.8140°E to 22.0784°S 113.8130°E, soft bottom, 102 m.

Diagnosis: Trunk unsegmented, cephalon with a long, thin, curved tubercle dorsally at base of chelifores; lateral processes long, highly adorned, each lateral process armed with a long, curved, filiform dorsal spur and with 3 to 4 triangular projections on both sides each tipped with a seta; first coxae follow same pattern with two long spurs dorsodistally. Ocular tubercle very tall, eyes visible, slightly pigmented. Auxiliary claws present, nearly half the length of main claw.

Description: Body of moderate size, trunk not segmented, dorsum smooth, lateral processes long, separated by V-shaped intervals, maximum distance twice their diameter, each with a long, thread-like dorsal spur (shorter on the last pair) and two to four lateral projections each side ( Fig. 6 A; 8C). Ocular tubercle tall, height about seven times the diameter at base, eyes at round tip ( Fig. 6 H). Abdomen as tall as ocular tubercle but heavier, pointing obliquely upward. Proboscis almost cylindrical, slightly inflated at distal half, truncate tip. Scape 1-segmented, with few distal setae; chelae slender, with long, curved fingers, tips crossing; 30 and 24 regular, thin teeth on movable and immovable finger respectively ( Fig. 6 I). Palp 7-segmented; second segment longest, with two distal setae, segments 3–6 subequal, with few setae, 7th segment very small, tipped with two long setae ( Fig. 6 G). Oviger ten-segmented, fifth segment longest, with bracelets of eggs attached; strigilis with simple spines in the formula 4:2:2:2; terminal claw not much longer than distal segment, with seven denticulations ( Fig. 6 E, F). Legs slender, smooth except for proximal coxae, first coxa with three lateral projections on each side, all tipped by a seta as in lateral processes; third coxa the shortest, femur as long as first tibia ( Fig. 6 B), cement glands open through seven pores ventrally on proximal half of femur ( Fig. 6 D); second tibia longest segment; tarsus very short, slightly shorter than main claw; tarsus + propodus + claw shorter than tibia 2; propodus straight with few internal setae; auxiliary claws nearly half length of main claw ( Fig. 6 C).

Measurements (in mm): Trunk length = 2.14; trunk width (across second pair of lateral processes) = 1.85, proboscis = 0.75, ocular tubercle = 1.1, abdomen = 1.07, palp segment 1 (p1) = 0.07, p2 = 0.38, p3 = 0.15, p4 = 0.06, p5 = 0.06, p6 = 0.045, p7 = 0.03; oviger segment 1 (o1) = 0.18, o2 = 0.18, o3 = 0.18, o4 = 0.61, o5 = 1.07, o6 = 0.18, o7 = 0.12, o8 = 0.1, o9 = 0.09, o10 = 0.09; coxa 1 = 0.5, coxa 2 = 0.53, coxa 3 = 0.44, femur = 1.44, tibia 1 = 1.41, tibia 2 = 1.52, tarsus = 0.14, propodus = 0.4, main claw = 0.2, auxiliary claw = 0.11.

Etymology: The species name relates to the presence of two (lat. bis = twice) thread-like tubercles on the lateral processes, instead of one as in P. filarium from the Caribbean.

Remarks: This is the first record of the genus Paranymphon in the southern hemisphere. Three species had been previously recorded: P. s p i n o s u m ( Caullery 1896), P. filarium Stock 1986 and P. magnidigitatum Hong & Kim 1987 from the Atlantic and Mediterranean ( Hedgpeth 1948; Nogueira 1956; Stock 1966; Stock 1978; 1978) North Pacific ( Hong & Kim 1987; Nakamura & Child 1991) and the Caribbean ( Stock 1986) respectively. This specimen from Western Australia shares the presence of long filiform spurs with P. filarium , also the tall ocular tubercle and abdomen and the proportions of the leg segments, but the prominent lateral projections on the crurigers, the extremely short tarsus and the auxiliary claws are not found in any of the other three species known. This record of Paranymphon suggests the genus could have a much wider distribution, but the patterns of colonization remain uncertain, as for most sea spiders.

Figures

FIGURE 6. Paranymphon bifilarium n. sp.. holotype male. A. Dorsal view; scale = 1 mm. B. Third leg; scale = 1 mm. C. Distal segments of third leg; scale = 0.1 mm. D. Ventral view of the femur with cement gland openings; scale = 1 mm. E. Oviger; scale = 0.5 mm. F. Strigilis. G. Palp. H. Frontal view of cephalon, ocular tubercle and chelifores. I. Details of chela. Scale bars G – I = 0.1 mm.

FIGURE 8. A. Hedgpethia calva n. sp., dorsal view. B. Parapallene challengeri, female, laterodorsal view; right legs 2 – 4 missing. C. Paranymphon bifilarium n. sp., dorsal view. D. Tanystylum zuytdorpi n. sp, dorsal view, three legs missing.