Austrodecus childi, Arango, 2003

Arango, Claudia P., 2003, Sea spiders (Pycnogonida, Arthropoda) from the Great Barrier Reef, Australia: new species, new records and ecological annotations, Journal of Natural History 37 (22), pp. 2723-2772 : 2734-2737

Austrodecus childi new species

(figure 5)

Type material. Holotype W, Pandora Reef, 3–6 m, among rubble and algae, 15 July 1999. Paratypes two juveniles, same locality, 19 April 2000 .

Other material. Townsville Port, piling scrapings, 3 m,?/ 2001, 2 X.

Diagnosis. Trunk with four dorsomedian tubercles, moderately tall, two long slender spines distally in all first coxae, one dorsodistal in femur, one long slender spine distally on femur and tibiae.

Description. Trunk length 0.9 mm, width 0.42 mm, fully segmented, lines of segmentation distinct, granulate surface, crurigers distanced by less than half their diameter, each segment with a dorsomedian slender tubercle half the length of the ocular tubercle, abdomen horizontal, somewhat curved downwards, with dorsal row of small granules. Ocular tubercle very tall, pointing obliquely towards the front, with rounded tip housing dark pigmented eyes (height 0.44 mm, width base 0.1 mm). Proboscis long, thin, strongly downcurved, joined to a basal stalk, otherwise typical pipette-like, about 25 annulations (length 0.7 mm). Palps slightly longer than proboscis, with six segments, all with small granules, segmentation line between second and third not clear, third segment the longest, with two dorsal tubercles, one at midpoint, another distally, ventral setae on fourth segment (total length palp 0.9 mm; 0.1–0.16–0.32–0.8–0.16–0.8), gland openings visible on second palp segment. Ovigers not found in any of the specimens. Legs not remarkably long, femur the longest segment, tibiae subequal, first coxa with two prominent, tubular distal spines forming a V-shape, longer than the dorsomedian tubercles, small dorsal tubular spine on third coxa and femur, two long simple spines on femur, one distally, other ventrally; both tibiae with a long distal spine; propodus curved, with no heel, feeble sole spines; main claw long and robust. Auxiliaries lacking (total length third leg 1.76; 0.1–0.12–0.1–0.4–0.3–0.25–0.07–0.32–0.18).

Etymology. This species is dedicated to Dr C. Allan Child, for his enormous contribution to the knowledge of sea spiders from all around the world, especially of those from remote locations.

Distribution. Only known from the inshore Pandora Reef and Townsville Port.

Remarks. This previously unknown species fits into the gordonae -section (Stock, 1957), appearing related to A. stocki Child, 1988 from the Indo-Pacific, A. palauense Child, 1983 from the Palau Islands and A. staplesi Stock found in New South Wales (Stock, 1990). They all have a similar armature in the distal segments of palps, have mid- to low median dorsal tubercles and are found in shallow tropical waters. Austrodecus childi differs from A. stocki in the lack of distal femoral spur (instead it has a mid-dorsal long tubercle not present in any other species), the shape of the trunk is not as compact as A. staplesi nor as elongate as A. palauense , the dorsal spurs in first coxae are longer than in any of the other species. Remarkably, males of this species do not show signs of ovigers. This absence has been attributed only to deep-sea species grouped in the subgenus Tubidecus (Stock, 1991) .