Austrarchaea milledgei Barrington Tops 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 : 30-32

Austrarchaea milledgei Barrington Tops Assassin Spider Rix & Harvey sp. n. Figs 7L9E2341

Type material.

Holotype male: Barrington Tops State Forest, 0.8 km E. of Moppy Picnic Area, New South Wales, Australia, 31°53'22"S, 151°33'57"E, pitfall trap, Nothofagus rainforest, 1250 m, 18.III.-30.IV.2008, G. Milledge, A. Hegedus (AMS KS103905).

Other material examined.

AUSTRALIA: New South Wales: Barrington Tops State Forest: same data as holotype except 31.I.-18.III.2008, 1 juvenile (AMS KS103409); same data as holotype except 18.XII.2007 - 31.I.2008, 1 juvenile (AMS KS 102056); same data as holotype except 14.XI.-18.XII.2007, G. Milledge, H. Smith, 1 juvenile (AMS KS104681); same data, 1 juvenile (AMS KS104696); off Barrington Tops Forest Road, 31°54'45"S, 151°29'45, sifting elevated leaf litter under tree ferns, Nothofagus rainforest, 1400 m, 14.IV.2010, M. Rix, D. Harms, 8 juveniles (WAM T112569DNA: Ar42-110-J/Ar42-111-J/Ar42-112-J). Barrington Tops National Park: Quarry Road turnoff, 31°54'45"S, 151°31'10"E, pitfall trap, Nothofagus rainforest, 1230 m, 31.I.-18.III.2008, G. Milledge, A. Hegedus, 1♂, 1 juvenile (AMS KS103340); same data except 18.XII.2007 - 31.I.2008, 1 juvenile (AMS KS102013); off Barrington Tops Forest Road, 31°54'22"S, 151°31'32, sifting elevated leaf litter, complex eucalypt forest with thick understory, 1376 m, 14.IV.2010, M. Rix, D. Harms, 1♀, 3 juveniles (WAM T112568DNA: Ar43-107-F/Ar43-108-J/Ar43-109-J).

Additional material examined (of tentative identification).

AUSTRALIA: New South Wales: Barrington Tops National Park: Gloucester Tops Road, 12.1 km W. of Gloucester River campground, 32°03'45"S, 151°36'02"E, pitfall trap, Nothofagus rainforest, 1260 m, 13.XI.-19.XII.2007, G. Milledge, H. Smith, 1♀ (AMS KS102950). Chichester State Forest: Bungari Road, 1 km from Mount Allyn Road, 32°08'S, 151°26'E, 940 m, 4. II– 9.IV.1993, M. Gray, G. Cassis, 1 juvenile (AMS KS38978).

Etymology.

The specific epithet is a patronym in honour of Graham Milledge, for collecting most of the specimens of this species, and for his efforts in documenting the remarkable spider fauna of the Barrington Tops region of New South Wales.

Diagnosis.

Austrarchaea milledgei can be distinguished from all other Archaeidae from mid-eastern Australia except Austrarchaea aleenae by the short, dense tuft of accessory setae on the male chelicerae (Fig. 23C); and from Austrarchaea aleenae by the broader, spur-like tegular sclerite 2 (TS 2) and much smaller TS 3 (Fig. 23E).

This species can also be distinguished from other genotyped taxa from mid-eastern Australia (see Fig. 3B) by the following unique nucleotide substitution for COII (n = 6): C(1490). The COII substitution T(1511) further distinguishes this species from all other mid-eastern Australian taxa except Austrarchaea monteithi .

Description.

Holotype male: Total length 3.08; leg I femur 2.73; F1/CL ratio 2.51. Cephalothorax dark reddish-brown; legs tan-brown with darker annulations; abdomen mottled grey-brown and beige, palest posteriorly, with darker reddish-brown dorsal scute and sclerites (Fig. 23B). Carapace tall (CH/CL ratio 2.12); 1.09 long, 2.31 high, 1.05 wide; ‘neck’ 0.53 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 0.87), carapace gently sloping and almost horizontal anterior to HPC; ‘head’ not strongly elevated dorsally (post-ocular ratio 0.26) (Fig. 9E). Chelicerae with dense tuft of accessory setae on anterior face of paturon (Fig. 23C). Abdomen 1.54 long, 1.13 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. Partially expanded pedipalp (Figs 23D-E) with rounded-rectangular, broadly-tapered conductor; tegular sclerite 1 (TS 1) long, spiniform, visible in retro-ventral view; TS 2 spur-like, shorter than TS 1, partially obscured by TS 3; TS 2a sinuous, filiform, exposed distally; TS 3 rectangular, embedded within distal haematodocha, overlying proximal embolic sclerite and TS 2.

Female (WAM T112568): Total length 3.74; leg I femur 2.96; F1/CL ratio 2.24. Cephalothorax dark reddish-brown; legs tan-brown with darker annulations; abdomen mottled grey-brown and beige (Fig. 23A). Carapace tall (CH/CL ratio 2.02); 1.32 long, 2.67 high, 1.23 wide; ‘neck’ 0.65 wide; bearing two pairs of rudimentary horns; highest point of pars cephalica (HPC) near middle of ‘head’ (ratio of HPC to post-ocular length 0.59), carapace gently sloping posterior to HPC; ‘head’ not strongly elevated dorsally (post-ocular ratio 0.21) (Fig. 7L). Chelicerae without accessory setae on anterior face of paturon. Abdomen 2.10 long, 1.41 wide; with three pairs of dorsal hump-like tubercles (HT 1-6). Internal genitalia with dense cluster of ≤ 15 variably shaped spermathecae on either side of gonopore, clusters meeting near midline of genital plate (Fig. 23F); innermost (anterior) spermathecae longest, sausage-shaped, curved antero-laterally; outermost (posterior) spermathecae bulbous; other spermathecae variably pyriform, mostly straight, directed antero-laterally.

Variation: Males (n=2): total length 3.08-3.23; carapace length 1.09-1.10; carapace height 2.21-2.31; CH/CL ratio 2.00-2.12. For female variation see Remarks (below).

Distribution and habitat.

Austrarchaea milledgei is known only from rainforest and mesic closed forest habitats on the Barrington Tops Plateau, in the Barrington Tops National Park and Barrington Tops State Forest, New South Wales (Fig. 41). A juvenile specimen from Chichester State Forest and a single female specimen from Gloucester Tops may also belong to this species (see Remarks, below).

Conservation status.

This species is a short-range endemic taxon ( Harvey 2002b), which although restricted in distribution, is abundant within the World Heritage-listed Barrington Tops National Park (M. Rix, pers. obs.). It is not considered to be of conservation concern.

Remarks.

Specimens of Austrarchaea from the Barrington Tops Plateaux (i.e. Barrington Tops, Gloucester Tops and Chichester State Forest) seem to exhibit a larger than normal amount of morphological and molecular variation, as highlighted by the deep (~6%) COI and COII sequence divergences observed among specimens collected along the Barrington Tops Forest Road in April 2010 (Fig. 3A), and the incongruous CH/CL ratio of the single female (AMS KS102950) from Gloucester Tops relative to the only known female from Barrington Tops (WAM T112568) (see Fig. 6). It is possible that two cryptic species may occur in sympatry on the various mountains and plateaux that make up the Barrington Tops region, although the current paucity of specimens makes this difficult to ascertain. For the purposes of this revision, specimens from the northern Barrington Tops National Park (and State Forest) are recognised as conspecific with the holotype of Austrarchaea milledgei , but further work is required to compare males from across the region, and to confirm the identification of the Gloucester Tops and Chichester State Forest populations.