Hydrobiosella tiarka sp. nov. Figures 5–7, 39 Holotype. Male. Victoria. Cement Ck nr Warburton (about 37°43'S, 145°43'E), 8 Dec. 1970, A. Neboiss (NMV, T-21407). Paratypes. Victoria. 7 males, collected with holotype; 4 males (specimen PT-584 figured), same loc. and coll., 27 Mar 1972; 1 male, same loc., 29 Sep 1990, B. Armitage; 1 male, Cement Ck, 5 Feb 1955, A. Neboiss; 1 male, same loc. and coll., 19 Nov 1955; 1 female (specimen CT-614 figured), Cement Ck, Mt Donna Buang, 8 Apr 1976, Cartwright; 1 male, same loc. and coll., 1 Dec 1976 (NMV). Other material examined. Victoria. 3 males, Cement Ck Mt Donna Buang-Warburton Rd, 23 Feb 2012, D. Cartwright; 1 male, Erica, 29 Jan 1960, A. Neboiss; 1 male, 1 female, Toorongo Falls, NE Noojee, 17 Dec 1970, A. Neboiss; 1 male, Brittania Ck, 6km S of Warburton, 27 Feb 1976, A. Neboiss; 3 males, 1 female, Ada R. on Ada River Rd, 37°50.8'S 145°52'E, 19 Jan 1979, Latrobe C Survey; 1 male, same loc. and coll., 10 Feb 1980 (NMV). Diagnosis. Males of Hydrobiosella tiarka can be separated from those of other species in the group by the small apical spine and slightly bulbous apex on segment X. Description. Wings similar to those of H. bandabanda (Fig. 1); length of forewing, male 6.7–9.8 mm; female 8.2–10.8 mm. Male. Segment IX with a shallow, wide V-shaped notch medially on distal margin (Fig. 7). Segment X in dorsal view, a ‘tongue-shaped’ process, with almost parallel sides in basal half, with a pair of very small knobs meso-laterally, tapered strongly distally to a small apical, slightly bulbous knob, length about 2.9 times width, without a central dorsal ridge or groove (Fig. 5); in lateral view broad-based, narrowed at basal third, slender with almost parallel sides in distal two thirds, with short apical spine (Fig. 6). Phallus generally tube-like, robust, with a pair of slightly divergent sub-apical spines (Figs 5, 6). Inferior appendages in lateral view, slender, with basal segment sub-rectangular, length about 2.8 times maximum width; harpago shorter, length about half length basal segment, length about 2.1 times maximum width, with broad rounded apex (Fig. 6). Female. Genitalia typical of genus, with a small projection on sternite IX meso-distally (Fig. 39). Etymology. Tiarka – Australian Aboriginal word for toothpick or sharp (apical spine on tergum X). Remarks. Twenty-six male and three female specimens of Hydrobiosella tiarka have been collected from six localities in eastern-central Victoria (latitudinal range 37°43'- 37°58' S).

Published as part of Cartwright, David I., 2012, Two further species groups and new species among Australian Hydrobiosella Tillyard: new species from south-eastern Australia (Trichoptera: Philopotamidae), pp. 245-258 in Memoirs of Museum Victoria 69 on pages 252-253, DOI: 10.24199/j.mmv.2012.69.03, http://zenodo.org/record/10666102