Austrarchaea helenae Illawarra Assassin Spider Rix & Harvey

Rix, Michael G. & Harvey, Mark S., 2011, Australian Assassins, Part I: A review of the Assassin Spiders (Araneae, Archaeidae) of mid-eastern Australia, ZooKeys 123, pp. 1-100 : 36-37

Austrarchaea helenae Illawarra Assassin Spider Rix & Harvey sp. n. Figs 9I2644

Type material.

Holotype male: Macquarie Pass National Park, Macquarie Pass, New South Wales, Australia, 34°34'S, 150°39'E, pitfall trap, 12-26.IX.1999, M. Gray, G. Milledge, H. Smith (AMS KS62774).

Other material examined.

AUSTRALIA: New South Wales: Macquarie Pass National Park: Macquarie Pass, off Clover Hill Road, 34°34'05"S, 150°39'25"E, sifting elevated leaf litter, subtropical rainforest, 828 m, 8.IV.2010, M. Rix, D. Harms, 3 juveniles (WAM T112561DNA: Ar30-124-J/Ar30-125-J/Ar30-126-J).

Additional material examined (of tentative identification).

AUSTRALIA: New South Wales: Morton National Park: Barrengarry Mountain, ANIC Berlesate, rainforest, 460 m, 20.XII.1967, R. Taylor, C. Brooks, 1 juvenile (ANIC).

Etymology.

The specific epithet is a patronym in honour of Helen Rix, for her love of the Illawarra Escarpment, and for her hospitality to the senior author during field work in eastern Australia.

Diagnosis.

Austrarchaea helenae can be distinguished from all other Archaeidae from mid-eastern Australia by the long, spiniform tegular sclerite 1 (TS 1) with a curled distal tip (Fig. 26D) combined with the bifurcate, plate-like TS 3 (Fig. 26D).

This species can also be distinguished from other genotyped taxa from mid-eastern Australia (see Fig. 3B) by the following 14 unique nucleotide substitutions for COI and COII (n = 3): G(243), A(291), T(555), C(654), C(843), G(849), C(901), T(903), T(990), A(1206), C(1209), C(1401), C(1500), C(1548).

Description.

Holotype male: Total length 3.13; leg I femur 2.69; F1/CL ratio 2.50. Cephalothorax dark reddish-brown; legs tan-brown with darker annulations; abdomen mottled grey-brown and beige, with darker reddish-brown dorsal scute and sclerites (Fig. 26A). Carapace tall (CH/CL ratio 2.01); 1.08 long, 2.17 high, 1.02 wide; ‘neck’ 0.53 wide; bearing two pairs of rudimentary horns; highest point of pars cephalica (HPC) near middle of ‘head’ (ratio of HPC to post-ocular length 0.57), carapace gently sloping and almost horizontal posterior to HPC; ‘head’ moderately elevated postero-dorsally (post-ocular ratio 0.35) (Fig. 9I). Chelicerae with short brush of accessory setae on anterior face of paturon (Fig. 26B). Abdomen 1.79 long, 1.28 wide; with three pairs of dorsal hump-like tubercles (HT 1-6); dorsal scute fused anteriorly to epigastric sclerites, extending posteriorly to first pair of hump-like tubercles; HT 3-6 each covered by separate dorsal sclerites. Expanded pedipalp (Figs 26C-D) with broadly-triangular, pointed conductor; tegular sclerite 1 (TS 1) long, spiniform, with curled distal tip, visible in retro-ventral view; TS 2 spiniform, shorter than TS 1, largely obscured by embolus and TS 3; TS 2a sinuous, filiform, exposed distally; TS 3 exposed, plate-like, overlying TS 2, with bifurcate, triangular apex directed toward proximal conductor.

Female: Unknown.

Distribution and habitat.

Austrarchaea helenae is known only from rainforest habitats in the Macquarie Pass National Park, on the Illawarra Escarpment of south-eastern New South Wales (Fig. 44). A juvenile specimen from Barrengarry Mountain (Morton National Park) may also belong to this species based on proximity.

Conservation status.

This species appears to be a rare short-range endemic taxon ( Harvey 2002b), with populations on the Illawarra Escarpment potentially threatened by land-clearing, habitat fragmentation and fire. Much of the original rainforest of the Illawarra region has been cleared for agriculture and livestock, and only isolated fragments of forest remain.