Hydrobiosella bispina

Cartwright, David I., 2010, Studies of Australian Hydrobiosella Tillyard: a review of the Australian species of the Hydrobiosella bispina Kimmins group (Trichoptera: Philopotamidae), Memoirs of Museum Victoria 67, pp. 1-13 : 2-3

Hydrobiosella bispina group

Diagnosis. Key features of males in the group are inferior appendages with the harpago elongate, often angled near middle, with a dark row of setae forming a fringe along ventral margin; segment X with a pair of lateral lobes, which usually end in small hooks.

Description. Head and nota dorsally brown to dark brown with setal warts and scutellum pale, abdomen brownish dorsally and ventrally, paler laterally; wings light brown to brown. Medium sized adults. Forewing length, males: 5.9–8.8 mm; females: 6.1–8.7 mm; forewing length about 2.9–3.0 times maximum width, wing venation similar to the type species H. stenocerca , R1 simple, forks 1, 2, 3, 4 and 5 present; forks 1 and 2 sessile; fork 2 with nygma, about 1.6–1.7 times length fork 1; fork 3 shorter, length 0.6–0.7 times length fork 2, fork 3 length about 2.0 times length footstalk, cross-veins r–m and m contiguous or nearly meeting at fork 3; fork 4 similar length to fork 3, fork length about 4 times length footstalk; fork 5 very long, length between 1.7–1.8 times length fork 4; discoidal cell closed, length about 4.5 times maximum width. Hind wing length about 2.5–2.6 times maximum width, with forks 1, 2, 3 and 5 present; fork 1 usually sessile, occasionally with very short footstalk; fork 2 sessile, nygma present, fork 2 length between 1.3–1.4 times fork 1 length; fork 3 length about 0.5–0.6 times fork 2 length, fork 3 similar length to footstalk; fork 5 very long, length between 2.1–2.2 times length fork 3; discoidal cell closed, length between 4.5 times maximum width; with three anal veins (fig. 1).

Male. Segment IX usually with a small rounded notch medially on ventrodistal margin (figs 7, 13), rarely without (figs 10, 19). Preanal appendages absent. Segment X mainly sclerotised with a central pale, mostly membranous mesal lobe, with one or two pairs of short hairs subapically (figs 5–6); with a pair of more pigmented lateral lobes, which usually end in small hooks (figs 8–9). Phallus generally tubelike, slightly dilated subapically, with a pair of slender, straight or slightly curved parameres arising from the phallus basolaterally (figs 2–3, 5–6). Inferior appendages two segmented, in lateral view, basal segment robust, harpago more slender, straight to sharply angled near middle (figs 3, 6).

Female. Genitalia typical of genus, sometimes with a small projection, which can be diagnostic, on sternite VIII mesodistally (figs 38–49).

Larva. Confirmed larvae are unknown, although Hydrobiosella spp AV8 and AV15 ( Cartwright, 1997) almost certainly belong to this group. Hydrobiosella sp. AV 8 larvae have been recorded mainly in riffle habitats from small to medium streams 2–13 m wide at low to moderate altitudes between 70–1200 m ( Suter et al. 2006). These larvae have the forecoxa with two sclerotised processes on the anterior margin and the anterior margin of the frontoclypeus convex.

Remarks. The 12 species in this group are known from eastern mainland Australia, ranging from northeastern Queensland to eastern Victoria (latitudinal range 16°35'– 37°18'S). Females of only six species have been associated.

Key to males of species of the Australian Hydrobiosella bispina group

1. Inferior appendages with harpago straight or with ventral margin forming a weakly obtuse angle (figs 3, 6) 2

– Inferior appendages with harpago neither straight nor with ventral margin forming a weakly obtuse angle, but forming almost a right angle (figs 21, 24, 36) 7

2. Segment X with a dorsal spine ( Fig. 3 ); NE-Qld H. unispina

– Segment X without a dorsal spine (figs 6, 9) 3

3. Segment X without subapical, lateral pair of hooks (figs 5–6); CE-NSW H. gurara

– Segment X with subapical, lateral pair of hooks (figs 8–9, 11–12) 4

4. Segment X in dorsal view with apex rounded, slightly bulbous and dorsoventrally flattened (figs 8–9); NE-NSW H. nandawar

– Segment X in dorsal view with apex not rounded and dorsoventrally flattened, slender and laterally compressed (figs 11–12, 14–15) 5

5. Segment X with robust subapical, lateral pair of hooks, apex slender in lateral view (figs 11–12); NE-Qld H. dugarang

– Segment X without robust subapical, lateral pair of hooks, apex not slender in lateral view (figs 14–15, 17–18) 6

6. Inferior appendages with harpago dilated slightly in apical half (fig. 15); E-Vic H. bilga

– Inferior appendages with harpago not dilated slightly in apical half (fig. 18); C-Qld H. mundagurra

7. Parameres very long, reaching tip of inferior appendages (figs 20–21); E-NSW H. bispina

– Parameres not very long, not reaching tip of inferior appendages (figs 23–24) 8

8. Inferior appendages with harpago curved strongly in distal half so apex is pointing downwards (fig. 24); SE-Qld H. arcuata

– Inferior appendages with harpago not curved strongly in distal half so apex is pointing posteriorly (figs 27, 30) 9

9. Segment X in dorsal view with apex tapered gradually, not constricted sub-apically (fig. 26); CE-NSW H. moorda

– Segment X in dorsal view with apex not tapered gradually, constricted subapically (figs 29, 32) 10

10. Segment X in lateral view with apex slightly bulbous, not curved downwards; subapical, lateral pair of hooks directed outwards (figs 29–30); SE-Qld H. woonoongoora

– Segment X in lateral view with apex not slightly bulbous, curved slightly downwards; subapical, lateral pair of hooks directed downwards (figs 32–33, 35–36) 11

11. Inferior appendages with basal segment tapered strongly distally; harpago not dilated slightly in distal half (fig. 33); CE-NSW H. thurawal

– Inferior appendages with basal segment not tapered strongly distally; harpago dilated slightly in distal half (fig. 36); CE-NSW H. yokunna

Figures

Figures 1–7. Hydrobiosella spp.; 1, Hydrobiosella arcuata Kimmins, wings; 2–7, Hydrobiosella spp., male genitalia in dorsal, lateral and part ventral views; 2–4, Hydrobiosella unispina sp. nov.; 2, dorsal; 3, lateral; 4, ventral, mesodistal margin of segment IX; 5–7, Hydrobiosella gurara sp. nov.; 5, dorsal; 6, lateral; 7, ventral, mesodistal margin of segment IX.