Hydrobiosella unispina sp. nov.

Figures 2–4, 38–39

Holotype. Male, Queensland, Mt Spec State forest, Camp Ck trib., 18°57'S, 146°10'E, 760 m, 11 Jun 1994, A. L. Sheldon (NMV, T- 20893).

Paratypes. Queensland. 1 male (specimen PT-2029 figured), Mt Spec, at light, 11 May 1975, R . Storey and D. Hancock; the following sites all Mt Spec State forest, 18°57'S, 146°10'E, A. L. Sheldon ; 1 male, Birthday Ck above weir, 820 m, 6 Dec 1993 ; 1 male, Camp Ck proper, 760 m, 11 Jun 1994 ; 1 male, 1 female (specimen CT-635 figured), Camp Ck trib., 760 m, 15 May 1994 ; 1 male, same site, 5 Dec 1993; 1 male, 1 female, same site, 15 Mar 1994; 1 male, same site, 12 Dec 1993; 2 males, 1 female, same site, 6 Jul 1994, 1 male, same site, 6 Nov 1993; 1 male, same site, 23 Apr 1994; 2 males, same site, 21 Nov 1993; 1 male, same site, 20 Dec 1993; 1 male, same site, 15 Oct 1993; 1 male, same site, 4 Mar 1994 (NMV) .

Other material examined. Queensland. 1 female, Upper Little Mossman R., Mt Lewis, 10 Dec 1974 , M. S. Moulds; 1 male, ‘top of the range’, 19 Butler Drive, Kuranda, 335 m, 16°48'S, 145°38'E, 1–15 Feb 2007 , D. C. F. Rentz (ANIC); the following sites all Mt Spec State forest, 18°57'S, 146°10'E, A. L. Sheldon : 1 male, 3 females, unnamed ck, Paluma Dam Rd, 860 m, 17 Jan 1994 ; 1 male, same site, 11 Jun 1994; 1 male, same site, 6 Jul 1994; 1 male, unnamed ck ‘cascade’, 920 m, 17 May 1994; 2 males, ‘ Confusion’ Ck, trib. to unnamed ck, Paluma Res., 17 May 1994 ; 2 females, Birthday Ck above weir, 820 m, 20 Dec 1993 ; 2 males, 1 female, same site, 22 Oct 1993; 1 male, same site, 6 Nov 1993; 2 females, same site, 13 Nov 1993; 1 female, same site, 21 Nov 1993; 1 male, Birthday Ck below falls, 760 m, 11 Jun 1994 ; 1 male, Birthday Ck, Iron Cabin, 790 m, 12 Feb 1994 ; 1 male, Birthday Ck, 870 m, 16 Jan 1994 ; 2 males, 1 female, same site, 31 Oct 1993; 2 males, Williams Ck trib., 745 m, 13 Nov 1993 ; 2 males, same site, 15 May 1994; 1 female, Camp Ck trib., 760 m, 13 Dec 1993 ; 1 female, Echo Ck trib., 735 m, 7 Nov 1993 (NMV).

Diagnosis. Hydrobiosella unispina can be separated from other species in the group by the dorsal spine on segment X and segment IX produced into a triangular point medially on distal margin.

Description. Wings similar to those of H. arcuata (fig. 1), length of forewing: male 6.7–8.0 mm, female 7.2–8.7 mm.

Male. Segment IX without a noticeable notch on mesodistal margin, instead produced into a triangular point (fig. 4). Segment X with mesal lobe broadbased, dorsoventrally compressed in distal two-thirds, with a mesodorsal spine (figs 2–3); in dorsal view, subtriangular or tongue shaped, tapered distally, length about 2.3 times maximum width, with a pair of lateral lobes, without projecting hooks (fig. 2); in lateral view slender, downcurved in distal two-thirds (fig. 3). Inferior appendages in lateral view, with basal segment subrectangular, length about 1.8–1.9 times maximum width; harpago nearly as long as basal segment, more slender, length about 3.5 times width, weakly (obtusely) angled near middle (fig. 3).

Female. Genitalia typical of genus, with a small triangular projection on sternite VIII mesodistally (figs 38–39).

Etymology. Unispina — Latin for ‘one spine’ (spine on tergum X).

Remarks. Hydrobiosella unispina is a common species and has been collected mainly from the Mt Spec area of northeastern Queensland (latitudinal range 16°35'– 18°57'S).