(Figs. 11, 15, 210, 248)

Hydraena magnetica Zwick, 1977: 180.

Type Material. Holotype (male): Queensland, Magnetic Island [ca. 19° 8' S, 146° 50' E] [labels: Magnetic I. N. Queensland A. M. Lea // Hydraena magnetica Zwick male Holotypus // DIGITAL IMAGE captured 2004 P. D. Perkins]. Deposited in the SAMA.

Differential Diagnosis. Similar in size, body form and plaques to H. miniretia; differing therefrom by the non-microreticulate pronotal interstices and the more finely punctate elytral series (Figs. 11, 12). The aedeagi of the two species differ distinctively (Figs. 15, 16).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.13/0.44; head 0.17/ 0.29; pronotum 0.29/0.37, PA 0.32, PB 0.33; elytra 0.67/0.44. Head and large pronotal macula piceous, margins of pronotum light to dark brown, elytra dark brown, legs and maxillary palpi light brown to testaceous.

Frons punctures slightly smaller than 1xef; interstices shining, 2–5xpd. Clypeus microreticulate laterally, finely sparsely punctate medially. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc slightly larger than those of frons, interstices shining, 2–3xpd, punctures denser at anterior, interstices ca. 1–2xpd; PF1 and PF4 absent; PF2 very small and shallow, nearly absent; PF3 shallow.

Elytral punctures about equal size of largest pronotal punctures. Intervals not raised, shining, width about 1xpd, as are interstices between punctures of a row. Apices in dorsal aspect gradually rounded to subtruncate, in posterior aspect margins form moderately strong angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/3/4. P1 laminate; median carina angulate in profile. P2 narrow, l/w ca. 2/1, sides parallel, apex blunt. Plaques narrow, elongate ovals, widely separated and nearly parallel to one another, located in posterior 1/3 of metaventrite on sides of shallow median depression. AIS flat, width at arcuate posterior margin 2–3x P2. Protibia slightly widened near midlength; metatibia with small indistinct setae on medial surface of distal 0.5. Last sternite and last tergite simple, symmetrical.

Aedeagus (Fig. 15) main-piece much wider distally than at base, with small, hook-like process on apical part of right side; distal piece (ventral view) with two lobes and two curving flagella; parameres simple, left slightly longer than right. Female last tergite with small apicomedian incision, setae slender, tapering; gonocoxite as illustrated (Fig. 210).

Distribution. Currently known from several localities in northern Queensland, three localities in southern Queensland, and two localities in Victoria (Fig. 248).

Material Examined (137): Queensland, 15 km NE Mareeba, MDPI intercept trap site No. 25, flight intercept trap, elev. 400 m, 16° 56' S, 145° 32' E, 7 January–12 February 1985, Storey & Halfpapp (1 QPIM); same locality, elev. 400 m, 16° 56' S, 145° 32' E, 20 March–1 May 1985, Storey & Titmarsh (2 QPIM); 30 km NE Brisbane, Mt. Nebo Road, Pond, ca. 200 m, Sclerophyll forest, elev. 540 m, 27° 24' S, 152° 48' E, 21 August 2004, M. A. Jäch (AU 1) (3 NMW); 40 Mile Scrub N. P. via Mt. Garnet, MDPI intercept trap site No. 13, flight intercept trap, 17° 40' S, 145° 7' E, 21 December 1985 – 10 January 1986, Storey & Heiner (2 QPIM); Boggy Ck., 75 km Cooktown, Cooktown Rd., 16° 37' S, 145° 21' E, 26 April 1976, E. B. Britton (7 ANIC); Broken River, 50 miles W of Mackay, 19° 32' S, 144° 54' E, 30 November 1968, S. Misko (5 ANIC); Burnett River, Mt. Perry Rd., 25° 23' S, 151° 46' E, 15 August 2004, A. Glaister (1 NMW); Danbulla St. For., via Atherton, 17° 10' S, 145° 39' E, 14 June 1978, D. Gibson (1 ANIC); Emu Creek, 20 km S. Mareeba, 16° 58' S, 145° 25' E, 20 October 1990, D. Larson (10 MCZ); Girraween N. P., Bald Rock Creek at "Under-ground Creek", ex. sand/gravel streambank, 28° 51' S, 151° 57' E, 22 January 1998, P. D. Perkins (64 MCZ); Mulgrave River, The Fisheries, 17° 11' S, 145° 44' E, 9 November 1990, D. Larson (1 MCZ); Palmerston N. P., Learmouth Creek, ca. 14 km SE Millaa Millaa, on loop road, ex. bare rocks in splash zone, 17° 34' S, 145° 42' E, 16 January 1998, P. D. Perkins (7 MCZ); Parmentier Crk., 7 miles SW Kuranda, 16° 49' S, 145° 38' E, 21 March 1969, J. Balfour-Browne (11 BMNH); Reedy St., George R. Cooktown Rd., 16° 28' S, 144° 46' E, 22 May 1976, E. B. Britton (3 ANIC); Victoria, Lerderderg River, 6.8 km N Bacchus Marsh, wet gravel and cobbles at edge of small river; dry sclerophyll forest, elev. 135 m, 37° 37' S, 144° 25' E, 20 September 1999, N. Porch (64) (18 ANIC); McKillops Bridge, Snowy River, gravel at edge of large and rising river; dry sclerophyll forest, elev. 185 m, 37° 5' S, 148° 23' E, 6 November 2000, N. Porch (NP 16) (1 ANIC).