Austrarchaea binfordae Kerewong 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 : 29-30

Austrarchaea binfordae Kerewong Assassin Spider Rix & Harvey sp. n. Figs 7K9D2240

Type material.

Holotype male: Kerewong State Forest, off McLeods Creek Road, New South Wales, Australia, 31°33'39"S, 152°34'44"E, sifting elevated leaf litter, subtropical rainforest, 15.IV.2010, M. Rix, D. Harms (AMS KS114969DNA: Ar46-106-M).

Paratypes: Allotype female, Kerewong State Forest, New South Wales, Australia, 28.XI.1978, D. Milledge (AMS KS13891); 1 male, same data (AMS KS13891).

Other material examined.

AUSTRALIA: New South Wales: Lorne State Forest: "Lorne State Forest", pitfall trap, 4.XI.1979, D. Milledge, 1 juvenile (AMS KS5624); same data except 5.VII.1979, D. Milledge, 1 juvenile (AMS KS5390).

Additional material examined (of tentative identification).

AUSTRALIA. New South Wales: Willi Willi National Park: Banda Banda Antarctic Beech Forest, off Banda Road, 31°09'47"S, 152°24'23"E, sifting elevated leaf litter, Nothofagus rainforest, 1045 m, 16.IV.2010, M. Rix, D. Harms, 2 juveniles (WAM T112580DNA: Ar47-104-J/Ar47-105-J).

Etymology.

The specific epithet is a patronym in honour of Dr Greta Binford, for her pioneering research on spider venoms and for contributing to a highly successful basal clades tour.

Diagnosis.

Austrarchaea binfordae can be distinguished from all other Archaeidae from mid-eastern Australia by the very long, spiniform tegular sclerite 1 (TS 1) (Fig. 22F) combined with the unique shape of the conductor (Figs 22D-E), which is thin and slightly curved laterally, with a ridged ventral margin.

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 = 1): C(291), C(369), C(489), C(720), C(807), T(1013), A(1014), A(1018), C(1019), A(1177), G(1214), C(1294), C(1312), G(1563).

Description.

Holotype male: Total length 2.64; leg I femur 2.63; F1/CL ratio 2.70. 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. 22B). Carapace tall (CH/CL ratio 2.16); 0.97 long, 2.10 high, 0.92 wide; ‘neck’ 0.44 wide; bearing two pairs of rudimentary horns; highest point of pars cephalica (HPC) near posterior margin of ‘head’ (ratio of HPC to post-ocular length 0.84), carapace gently sloping and almost horizontal anterior to HPC; ‘head’ not strongly elevated dorsally (post-ocular ratio 0.31) (Fig. 9D). Chelicerae with brush of accessory setae on anterior face of paturon (Fig. 22C). Abdomen 1.38 long, 1.05 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. Unexpanded pedipalp (Figs 22D-F) with thin, slightly curved conductor with ridged ventral margin; tegular sclerite 1 (TS 1) very long, spiniform, visible in retrolateral view; TS 2 spur-like, poorly-sclerotised, shorter than TS 1; TS 2a sinuous, largely obscured by TS 2; TS 3 indistinct, embedded within distal haematodocha, barely visible beyond retro-distal rim of tegulum.

Allotype female: Total length 4.15; leg I femur 2.82; F1/CL ratio 2.39. Cephalothorax reddish-brown; legs tan-brown with darker annulations; abdomen mottled grey-brown and beige (Fig. 22A). Carapace tall (CH/CL ratio 2.19); 1.18 long, 2.58 high, 1.08 wide; ‘neck’ 0.59 wide; bearing two pairs of rudimentary horns; highest point of pars cephalica (HPC) near posterior third of ‘head’ (ratio of HPC to post-ocular length 0.64), carapace gently sloping posterior to HPC; ‘head’ not strongly elevated dorsally (post-ocular ratio 0.28) (Fig. 7K). Chelicerae without accessory setae on anterior face of paturon. Abdomen 2.62 long, 2.21 wide; with three pairs of dorsal hump-like tubercles (HT 1-6). Internal genitalia with cluster of ≤ 12 variably shaped spermathecae on either side of gonopore, clusters meeting near midline of genital plate (Fig. 21G); innermost (anterior) spermathecae longest, sausage-shaped, curved antero-laterally; other spermathecae variably pyriform, straight, directed antero-laterally.

Variation: Males (n=2): total length 2.64-2.92; carapace length 0.97-1.03; carapace height 2.10-2.18; CH/CL ratio 2.13-2.16.

Distribution and habitat.

Austrarchaea binfordae is known only from lowland subtropical rainforest habitats in the Kerewong and Lorne State Forests, near Wauchope, New South Wales (Fig. 40). Two juvenile specimens from Mount Banda Banda (Willi Willi National Park) may also belong to this species, but possess divergent mtDNA sequences indicative of possible speciation (Fig. 3B).

Conservation status.

This species appears to be a rare short-range endemic taxon ( Harvey 2002b), with populations in the Kerewong and Lorne State Forests potentially threatened by land-clearing, habitat degradation, fire and climate change. It is one of the few archaeids known to occur in lowland rainforest habitats in south-eastern Australia, and many of these habitats have been severely impacted by forestry activities.