Hedgpethia calva, 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 : 5-7

Hedgpethia calva n.sp.

( Figure 3 , 8A )

Material examined. Holotype: WAM T92360, 1 female. 24 November 2005, Bald Island, Western Australia, CSIRO station 036-008, collected by beam trawl, from 35.2815°S 18.7090°E to 35.2810°S 118.7090°E, soft bottom, 980 m. Paratypes: Details as for holotype. NMV JM54989, 2 males.

Diagnosis: Proboscis almost 1.5 times as long as trunk, spindle-shaped, with short narrow base. Ocular tubercle tall, with pointed apex inclined forward. Palp segments 1 to 5 glabrous, no spines or setae. Legs smooth, only few tiny setae, propodus longer than tarsus, main claw longer than half propodus length.

Description: Body large for the genus, slender, leg span 27.3 mm. Trunk completely segmented, posterior rims slightly inflated, lateral processes separated from each other by about their own diameter, glabrous ( Fig. 3 A, 8A). Ocular tubercle tall, height almost twice its basal width, with long, curved apical cone projecting forward; eyes pigmented, equal-sized ( Fig. 3 B). Proboscis 1.36 times as long as trunk, slightly downcurved, narrow base 6% of total proboscis length, then swollen reaching maximum width at midpoint; constriction mark on anterior portion at 40% of total length, tapering distally ( Fig. 3 B; 8A); lips rounded, deep commissures. Abdomen ventrally oriented, not seen in dorsal view, very small, anus apical. Palps longer than proboscis, slender; 10-segmented, third segment longest, glabrous; fifth about half length of third, with sparse setae distally; three distal segments subequal, seventh slightly shorter; long setae ventrally on segments six to ten ( Fig. 3 C). Oviger slender, 10-segmented, fourth segment longest, sixth slightly shorter, with few scattered setae ( Fig. 3 G); strigilis with three rows of simple spines on each segment, distal ones longer; terminal claw very short, leaf-like, about one-fifth as long as terminal segment ( Fig. 3 F). Legs very slender, with sparse tiny setae, third coxae slightly shorter than first, second coxae longest, femur longer than second tibia, thickened distally, with distal seta dorsally; first tibia longest segment; propodus longer than tarsus ( Fig. 3 E); main claw 0.6 times length of propodus ( Fig. 3 D). Genital pores on all pairs of legs, female pores typical, larger and towards centre of coxa, male pores closer to distal margin of the coxa.

Measurements of holotype (in mm): trunk length = 3.23, trunk width (across second pair of lateral processes) = 1.32; proboscis = 4.41; palp length = 9.89, segment 1 (p1) = 0.26, p2 = 0.09, p3 = 3.52, p4 = 0.52, p5 = 2.11, p6 = 0.38, p7 = 0.7, p8 = 0.85, p9 = 0.79, p10 = 0.67; oviger length = 7.4, segment 1 (o1) = 0.15, o2 = 0.31, o3 = 0.28, o4 = 1.85, o5 = 0.46, o6 = 2.41, o7 = 0.58, o8 = 0.55, o9 = 0.46, o10 = 0.35; coxa 1 = 0.49, coxa 2 = 0.69, coxa 3 = 0.35, femur = 5.31, tibia 1 = 6.56, tibia 2 = 5, tarsus = 1.17, propodus = 1.47, claw = 0.97.

Etymology: From calva (lat.) meaning bald, bare, referring to the type locality, Bald Island, WA. It also applies to the glabrous appearance of proximal segments of palps and legs in comparison to H. dampieri , also known from WA.

Remarks: These specimens could not be attributed to Hedgpethia dampieri ( Child 1975) because of 1) different proboscis: body proportion, 1.36 in the specimens from Bald Island, 0.84 in H. dampieri ( Child 1975; Staples 2007); 2) the main claw being shorter than the propodus, not subequal as in H. dampieri ; 3) the lateral processes being closer together than twice their diameter as in H. dampieri , and 4) the lack of spines on the third segment of the palp and on the legs of the new species, while spines and setae on these are the main characteristic of H. dampieri . Also, the palp segments are longer in the new species.

Hedgpethia dampieri was described from West Lancelin I., WA, from 120 m and recorded from other locations in WA ( Child 1975). The specimens herein occur within that range of geographic distribution but at almost 1000 m depth. They differ from H. eleommata Child 1998 from New Zealand in the long, pointed ocular tubercle, not having such noticeable larger, dark-pigmented anterior eyes ( Child 1998). Hedgpethia calva n. sp. has a larger proboscis not so sharply curved and a longer propodus with a shorter claw; in other aspects the two species are very similar. A species from deep waters in New Caledonia, H. tibialis ( Stock 1991) , shows a similar tarsus: propodus proportion to the species reported here, but the tibiae are extremely long and slender and the ocular tubercle low and blunt. Hedgpethia dofleini ( Loman 1911) , a species widely distributed in the North Pacific is about 30% larger in body size, the tarsus is longer in relation to propodus and the oviger claw is relatively longer. Another apparently related Pacific species is Hedgpethia elongata Takahashi, Dick and Mawatari 2007 from Japan, similar in the configuration of trunk, ocular tubercle and strigilis ( Takahashi et al. 2007), but the Australian species does not have such a long basal stalk to the proboscis.

Figures

FIGURE 3. Hedgpethia calva n. sp., holotype female. A. Dorsal view. B. Lateral view. C. Palp. D. Details of distal segments of third leg. E. Third leg. F. Oviger strigilis. G. Oviger. All scale bars = 1 mm except G = 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.