Hydraena rudallensis Blackburn, 1896

PERKINS, PHILIP D., 2007, A revision of the Australian species of the water beetle genus Hydraena Kugelann (Coleoptera: Hydraenidae), Zootaxa 1489 (1), pp. 1-207 : 69-70

Hydraena rudallensis Blackburn, 1896

(Figs. 104, 105, 108–110, 215, 230, 242)

Hydraena rudallensis Blackburn, 1896: 261 .

Hydraena rudallensis Blackburn ; Zwick, 1977: 170.

Type Material. Holotype (male): Northern Territory, Rudall's Creek [labels: Rudall's Cr. // Cent Ausl. coll. Horn Exp. Pres 7-94 // Type // [red rectangle] // HYDRAENA rudallensis Blackb. // DIGITAL IMAGE captured 2004 P. D. Perkins // HOLOTYPE T-13134 Hydraena rudallensis Blackburn, 1896 ]. Deposited in the MVMA.

Differential Diagnosis. Similar in size, color and dorsal punctation to H. blackburni (Figs. 104–107); differing therefrom by the proportionally larger pronotum, and the dissimilar plaque ratios (1/1/2.2/1 vs. 2/1/5/ 2). The aedeagi of the two species markedly differ (Figs. 108–111, 113).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.40/0.58; head 0.23/ 0.33; pronotum 0.35/0.45; elytra 0.79/0.58. Dorsum brown, head and disc of pronotum piceous, legs and palpi testaceous.

Frons punctures ca. 1xef; interstices shining, 0.5–3xpd. Clypeus microreticulate laterally, finely sparsely punctate medially. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc ca. 1–2xpd those of frons, interstices shining, 2– 4xpd, punctures denser at anterior; PF1 and PF4 absent; PF2 very shallow; PF3 shallow.

Elytral punctures very faint, about 0.3xpd of largest pronotal punctures. Intervals not raised, shining, width about 3xpd, as are interstices between punctures of a row. Apices in dorsal aspect gradually rounded, subtruncate, in posterior aspect margins form shallow angle with one another.

Plaque/intercoxal process ratios (P2/w/l/s) ca. 1/1/2.2/1/. P1 laminate; median carina posterior extreme slightly more elevated than remainder. P2 l/w ca. 1/1, sides parallel, apex blunt. Plaques located in posterior 7/10 of metaventrite on sides of deep median elongate subtriangular depression, plaques anteriorly very narrowly separated. AIS flat, width at arcuate posterior margin 2–3x P2. Protibia with small swelling on inner surface at distal 3/4. Metatibia simple. Last sternite symmetrical or nearly so; last tergite with small apicomedian tooth.

Aedeagus (Fig. 108–110) main-piece with three strongly sclerotized processes, one on ventral surface near midlength, and two on right side, both (in ventral view) arcuate, sharply pointed, and of similar shape; distal piece with several irregularly shaped lobes (which vary in shape among populations), in ventral view lobes oriented toward left side, basal lobe on dorsal surface covered by arcuate setae, gonopore-bearing flagellum short, pointing toward left side; both parameres inserting near base, of about equal length; left paramere slightly widened apically and with numerous long setae, some with widened, flat tips; right paramere markedly arcuate, with cluster of unusual, distally widened and flattened setae near midlength. Female last tergite with three incisions, delimiting four lobes, setae slender, tapering; gonocoxite and spermatheca as illustrated (Figs. 215, 230).

Distribution. Widely distributed in the eastern one-half of Australia, with populations in the 'center' and a few records in western Western Australia (Fig. 242).

Remarks. The aedeagus shows variation in the shapes of the lobes of the distal piece and the degree of flattening of the tips of the setae. I have illustrated the holotype aedeagus and a variant from Queensland, Girraween National Park (Figs. 108–110).

Material Examined (217): New South Wales, Armidale, 30° 30' S, 151° 39' E, 21 March 1963, C. Watts (1 SAMA); Beaury Creek, adjacent Woodenbong State Forest, ca. 8 km SW Woodenbong, ca. 120 km SW Brisbane, Residual pools and small rock pools in river bed (Beaury Creek), in cultivated cattle country, 28° 24' S, 152° 32' E, 25 August 2004, M. A. Jäch (AU 14) (7 NMW); Forbes, 33° 22' S, 148° 0' E, 15 March 1963, C. Watts (1 SAMA); Gilgandra, 31° 42' S, 148° 40' E, 19 November 1992, C. Watts (3 SAMA); Nepean River, Goates, Chain of Ponds [no date], 34° 16' S, 149° 46' E ,, Common (2 SAMA); Nyngan, 31° 33' S, 147° 12' E, 16 March 1963, C. Watts (1 SAMA); Parramatta, 33° 48' S, 151° 0' E, 26 March 1965, M. E. Bacchus (MEB 217) (1 BMNH); Prospect/St. Mary's Road, 33° 47' S, 150° 55' E, 24 March 1965, M. E. Bacchus (MEB 212) (2 BMNH); Shaw Creek, Springwood/Richmond Rd., elev. 8 m, 33° 38' S, 150° 38' E, 24 March 1965, M. E. Bacchus (MEB 214) (11 BMNH); Windsor [no date], 33° 36' S, 150° 48' E ,, Lea (1 SAMA); Northern Territory, Ellery Creek, Big Hole, 23° 50' S, 132° 58' E, 16 March 1998, C. H. S. Watts (44 SAMA); Ellery Gorge, 85 km. W of Alice Springs, 23° 46' S, 133° 4' E, 5 November 1979, T. Weir (11 ANIC); Finke Gorge N. P., gorge west of Finke River, permanent & temporary rock pools, algal growth, detritus, 24° 8' S, 132° 51' E, 15 March 1995, T. Weir (10 ANIC); Finke Gorge N. P., Kanara Ck. at The Oasis, permanent rock pools, palms, grass at edges, algal growth, 24° 4' S, 132° 44' E, 12 March 1995, T. Weir (2 ANIC); Finke Gorge N. P., Little Palm Creek, rock pools, palms, algal growth, overhanging vegetation, 24° 6' S, 132° 46' E, 13 March 1995, T. Weir (2 ANIC); Finke Gorge N. P., Palm Valley, small temporary pools, rocky, some sandy base, algal growth, detritus, 24° 3' S, 132° 43' E, 14 March 1995, T. Weir (5 ANIC); Hugh River, 12.5 km SSE of Paisley Bluff, flowing river, deep pool, grass at edges, sandy bottom, 23° 49' S, 133° 22' E, 7 March 1995, T. Weir (2 ANIC); Illamurta Springs Conservation Reserve, small rock pool, sandy bottom (temporary), 24° 19' S, 132° 41' E, 16 March 1995, T. Weir (4 ANIC); Ormiston Gorge, 23° 37' S, 132° 43' E, 16 March 1998, C. Watts (4 SAMA); Palm Valley, 24° 4' S, 132° 45' E, 1–30 April 1968, C. Watts (5 SAMA); Serpentine Gorge, West Macdonnells N. P., permanent rocky pools, sandy bottom, overhanging and floating vegetation, 23° 44' S, 132° 59' E, 8 March 1995, T. Weir (1 ANIC); Standley Chasm, 23° 43' S, 133° 27' E, 25 July 1969, D. D. Giuliani (2 WAMP); Vaughan Sp., 22° 18' S, 130° 51' E, 1–30 April 1968, C. Watts (3 SAMA); Queensland, 40 km S Beaudesert, Running Creek, along road between Mt. Chinghee N. P. and Border Ranges N. P., at 7th Bridge, stream, ca. 5–8 m wide, including rockpools, flowing through open forest ( Casuarina , Eucalyptus ), 28° 19' S, 152° 55' E, 25 August 2004, M. A. Jäch (AU 13) (5 NMW); 60 km S Brisbane, 10 km NNW Canungra, 27° 57' S, 153° 8' E, 25 August 2004, M. A. Jäch (AU 11) (4 NMW); Albert River, S of Wolfdene, 30 km SE Brisbane, River (Albert River), ca. 20 m wide, slightly polluted, flowing through cultivated land, elev. 30 m, 27° 46' S, 153° 11' E, 21 August 2004, M. A. Jäch (AU 3) (6 NMW); Burdekin R., E of Charters Towers, 20° 0' S, 146° 26' E, 4 May 1998, C. Watts (6 SAMA); Burnett River, Mt. Perry Rd., 25° 23' S, 151° 46' E, 15 August 2004, A. Glaister (1 NMW); Carnarvon Ck. 17 km E Park Office, 25° 1' S, 148° 18' E, 14 August 2004, A. Glaister (8 NMW); Ch[arters] Towers, 20° 0' S, 146° 14' E, 3 February 1936, A. A. Ross (1 UQIC); Connor’s River, 91.5 miles S Mackay, 22° 39' S, 149° 4' E, 3 September 1972, H. E. Hinton (4 BMNH); Edungalba, flight intercept trap, 23° 43' S, 149° 50' E, 1 January 1987, H. & A. Howden (1 ANIC); Gatton, 27° 32' S, 152° 3' E, 9 October 1932, [collector not given] (1 QDPC); same locality, 27° 32' S, 152° 3' E, 9 November 1932, [collector not given] (6 QMBA); 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 (3 MCZ); Gladstone [no date], 23° 52' S, 151° 16' E ,, Lea (1 SAMA); Goondiwindi, 14 km NE, in debris at edge of pond, 28° 29' S, 150° 23' E, 25 October 1991, T. Gush (5 ANIC); Greenvale 70 km SW, at light, 19° 23' S, 144° 37' E, 1–10 March 1996, A. J. Watts (1 SAMA); Lamington N. P., Moran’s Creek, 80 km S Brisbane, elev. 760–820 m, 28° 14' S, 153° 8' E, 24 August 2004, M. A. Jäch (AU 9) (4 NMW); Magnetic Island [no date], 19° 8' S, 146° 50' E ,, A. M. Lea (1 SAMA); South of Charleville, 26° 24' S, 146° 20' E, 9 May 1973, M. S. Upton (1 ANIC); Taroom Dist. Boggom.2, 159, 25° 26' S, 150° 1' E, 8 June 1996, R. Kristensen (3 QMBA); Young’s Crossing, Petrie, 27° 16' S, 152° 57' E, 2 October 1959, I. C. Yeo (1 UQIC); South Australia, Alligator Gorge, 32° 44' S, 138° 4' E, 1– 30 June 1959, C. Watts (4 SAMA); Buckaringa Gorge, Flinders Ra. c. 30 km NNW of Quorn, light trap, 32° 6' S, 138° 2' E, 19 December 1985, Reid, Gullan & Lewis (1 ANIC); Cooper Creek, Innaminka, 27° 44' S, 140° 44' E, 21 July 1994, Aust. water quality centre 3782 (2 SAMA); Mambray Creek, Mt. Remarkable Nat. Pk., 32° 51' S, 137° 57' E, 7 May 1981, J. A. Forrest (4 SAMA); Wockerawirra Ck., Nth. Flinders, 31° 11' S, 138° 38' E, 26 July 1976, P. Suter, B. Mitchell, R. Marchant (1 SAMA); Victoria, Kororoit Creek, at Sydenham/ Melton Road, organic mud and litter at edge of pool in dry creek in pasture and degraded riverine forest, elev. 110 m, 37° 41' S, 144° 38' E, 17 February 2002, N. Porch (91) (7 ANIC); Nathalia, 36° 3' S, 145° 12' E, 18 January 1961, C. Watts (1 SAMA); Yellow Creek, at crossing of Ovens Highway, Wangaratta, coarse sand and gravel at wet margins of gravel bar of red gum lined creek in pasture, elev. 145 m, 36° 21' S, 146° 20' E, 15 December 2001, N. Porch (88) (1 ANIC); Western Australia, 7 miles NE of Giles, 24° 57' S, 128° 22' E, 9 July 1969, D. D. Giuliani (5 WAMP); Billy Well Creek, 20 km NE Mt. Sandiman H. S., at light at night, 24° 18' S, 115° 31' E, 11–13 May 1981, H. Hanich & T. F. Houston (1 WAMP); Woodstock Station, at UV florescent light at night 6:00 to 7:30 PM, 21° 37' S, 119° 1' E, 24 September 1988, B. P. Hanich (site WS 9) (2 WAMP).