Gymnochthebius setosus, Perkins, 2005

Perkins, Philip D., 2005, A revision of the water beetle genus Gymnochthebius Orchymont (Coleoptera: Hydraenidae) for Australia and Papua New Guinea, Zootaxa 1024 (1), pp. 1-161 : 1-161

Gymnochthebius setosus new species

( Figures 3 , 4 , 75, 94–97)

Type Material. Holotype (male): Australia: Victoria: Narracan Falls , 4.1 km NE Thorpdale, on mud at edge of stream flowing through pasture, elev. 190 m, 38° 16' S, 146° 13' E, 4 February 1999, N. Porch (NP 27). Deposited in the ANIC . Paratypes (851): Australia: Australian Capital Territory: Black Mtn. , light trap, 35° 16' S, 149° 6' E, 25 March 1968, M. S. Upton (1 ANIC) ; Canberra, stream entering L. Burley­Griffin , 35° 18' S, 149° 7' E, 30 March 1965, M. E. Bacchus (MEB 221) (3 BMNH) ; Paddy's River , 1 mi. S of Cotter Dam, 35° 29' S, 148° 59' E, 17 April 1969, S. Misko (1 ANIC) ; Paddy's River, nr. Murray's Corner , 35° 25' S, 148° 57' E, 3 April 1965, M. E. Bacchus (MEB 231) (1 BMNH) ; Paddy's River , 35° 29' S, 148° 59' E, 16 January 1969, J. Balfour­Browne (1 BMNH) ; Uriarra Crossing on Murrumbidgee River , quartz gravel and 'micro' mudflats at receding edge of large flowing river, elev. 445 m, 35° 14' S, 148° 57' E, 14 October 2000, N. Porch (NP 18) (20 ANIC) ; Wombat Creek , 6 km NE of Piccadilly Circus, flight intercept window/ trough trap, elev. 750 m, 35° 19' S, 148° 51' E, 1–30 October 1985, Weir, Lawrence, Johnson (1 ANIC) ; New South Wales: Bemboka River at Greens Crossing , 1 km N of Bemboka, gravel and sand of small sandbank at edge of river, elev. 195 m, 36° 37' S, 149° 34' E, 9 April 2000, N. Porch (NP 28) (2 ANIC) ; Hunter River, Moonan Flat , 31° 55' S, 151° 14' E, 6 December 2002, A. Glaister (1 SAMA) ; Khancoban Creek, Khancoban , elev. 304.8 m, 36° 9' S, 148° 12' E, 1 April 1965, M. E. Bacchus (MEB 230) (1 BMNH) ; Nepean River, 33° 43' S, 150° 39' E, 7 September 1929, H. J. Carter (2 AMSA, 2 UQIC); nr. Sydney, Beecroft , 33° 44' S, 151° 3' E, 26 March 1965, M. E. Bacchus (MEB 215) (16 BMNH) ; Prospect ­ St. Mary's Road , 33° 47' S, 150° 55' E, 24 March 1965, M. E. Bacchus (MEB 212) (5 BMNH) ; Shaw Creek, c. 8 m., Springwood­Richmond Rd. , 33° 38' S, 150° 38' E, 24 March 1965, M. E. Bacchus (MEB 214) (5 BMNH) ; Sydney , 33° 52' S, 151° 12' E, E. W. Ferguson Collection (2 ANIC) ; Queensland: Beechmont , 28° 7' S, 153° 10' E, 27 March 1932, Wassell (1 MCZ) ; Kilcoy , 11 km E, in creek debris, 26° 56', 152° 40' E, 19 October 1991, T. Gush (2 ANIC) ; Moran's Creek, SW of O'Reilly's Rainforest Guesthouse, Lamington NP, ca. 80 km S Brisbane [beeline], 28° 14’11.2”S 153° 08’ 01.1”E – 28° 13’59”S 153° 07’ 27”E, River ( Moran's Creek ), ca. 2–4 m wide, through dense rain forest, Eucalypt forest and open grassland, 760–820 m a.s.l., M. A. Jäch (AU 9) (1 NMW) ; Mt. Nebo Road, SE Mt. Nebo, ca. 540 m a.s.l., ca. 30 km NE Brisbane [beeline], 27°24'08S' ' 152°48'00'' E, Pond, ca. 200 m, Sclerophyll forest , 21 August 2004, M. A. Jäch (AU 1) (8 NMW) ; N.Q., Bushy Creek, Mossman ­ Mt. Lewis Rd. , elev. 365.76 m, 16° 37' S, 145° 21' E, 30–31 October 1966, E. Britton (1 ANIC) ; Oxley Creek , 27° 32' S, 153° 0' E, 2 July 1932, Wassell (1 UQIC) ; Running Creek, along road between Mt. Chinghee NP and Border Ranges NP, at Seventh Bridge , ca. 40 km [beeline] S Beaudesert, 28° 19’13.2”S 152° 55’ 39.1”E, River ( Running Creek ), ca. 5–8 m wide, incl. rockpools, through open forest (Casuarina, Eucalypt), 25 August 2004, M. A. Jäch (AU 13) (10 NMW) ; Stream, at Cedar Creek Road, above Cedar Creek Falls , below Eagle Heights , ca. 40 km SSE Brisbane [beeline], 27°53’50.0” S 153° 10’49.3” E, ca. 4 m wide, riffles, boulders, rock pools, sand margins, through forest, 22 August 2004, M. A. Jäch (AU 5) (10 NMW) ; Tasmania: Creekton Rivulet , 2 km S of Strathblane, thick weedy litter and organic mud at edge of small pool of creek in dry sclerophyll forest/scrub, elev. 10 m, 43° 21' S, 146° 58' E, 19 February 2000, N. Porch (20) (56 ANIC) ; Frankford [no date], 41° 20' S, 146° 46' E, Lea (1 MVMA) ; Junee River, 0.2 km downstream of Junee Cave , sandy mud at bottom of riverbank in regrowth rainforest/wet sclerophyll forest, elev. 300 m, 42° 34' S, 146° 36' E, 18 February 2000, N. Porch (2) (22 ANIC) ; Little Piper River at bridge on B82, sandy litter at edge of river in scrubby forest, elev. 15 m, 41° 2' S, 147° 14' E, 12 February 2000, N. Porch (3) (16 ANIC) ; Mount, creek Barrow , inundation debris, 41° 22' S, 147° 21' E, 8 December 1982, Endrödy­Younga (AU­101) (14 TMSA) ; Pipers Brook at B82 bridge, 2.7 km NW of Pipers Brook, muddy litter at edge of small pools of perrenial creek, elev. 50 m, 41° 3' S, 147° 10' E, 12 February 2000, N. Porch (17) (51 ANIC) ; Polleys Creek , just S of Chinamans Corner on Mathinna Plains Road, coarse gravel at edge of small creek at road edge; rainforest, elev. 780 m, 41° 22' S, 147° 36' E, 13 February 2000, N. Porch (1) (3 ANIC) ; St Patric Riv. Targa , inundation debris, 41° 18' S, 147° 21' E, 8 December 1982, Endrödy­Younga (AU­104) (14 TMSA) ; Victoria: 1 km N Possum Hollow, W. br. Tarwin River, 4.6 km SSW Allambee , ex shaded silty mud at edge of small 'creek' at pasture­wet sclerophyll forest boundary, elev. 240 m, 38° 18' S, 146° 1' E, 14 January 1999, N. Porch (NP 19) (19 ANIC) ; 10 km NE Mirranatwa , small creek bed ­ drying pool, stony, dead leaves, dry sclerophyll forest, 37° 36' S, 142° 13' E, 12 October 1997, C. Watts (1 SAMA) ; Brisbane Ranges National Park , 8.2 km W Rowsley Trig., litter and mud at edge of small firedam in dry sclerophyll forest, elev. 405 m, 37° 44' S, 144° 16' E, 1 January 2000, N. Porch (60) (10 ANIC) ; Bullock Creek, at Forest Road , 13 km N of Longwarry, gravel and litter at edge of small shaded forest stream flowing through wet sclerophyll forest, elev. 135 m, 37° 58' S, 145° 49' E, 1 January 2003, N. Porch (79) (2 ANIC) ; Bunyip R. at Princes Highway , amongst willow roots and on sand at edge of river under thick willow cover in pasture, elev. 40 m, 38° 5' S, 145° 45' E, 15 January 1999, N. Porch (NP 22) (6 ANIC) ; Dandenong Creek at Brady Road, Dandenong North , mud at edge of artificial dam in pasture, elev. 30 m, 37° 57' S, 145° 13' E, 28 September 1999, N. Porch (53) (14 ANIC) ; Elizabeth Ck. , 1.2 km S Childers, very abundant in sandy mud and wet litter (80cm by 20cm) along edge of small forest creek in wet sclerophyll forest ( Eucalyptus regnans ), elev. 195 m, 38° 19' S, 146° 6' E, 28 October 1998, N. Porch (NP 09) (4 ANIC) ; Elizabeth Ck. , 1.5 km N Allambee South, mud at edge of creek flowing under shady willows, elev. 125 m, 38° 20' S, 146° 7' E, 11 September 1998, N. Porch (NP 05) (10 ANIC) ; Franklin River at South Gippsland Highway , on and in shaded silty mud at edge of small 'creek' in pasture, elev. 10 m, 38° 39' S, 146° 18' E, 13 January 1999, N. Porch (NP 14) (3 ANIC) ; Genoa River at Genoa , u/s of old highway bridge, gravel at edge of small river flowing through pasture, elev. 10 m, 37° 28' S, 149° 35' E, 10 April 2000, N. Porch (NP 25) (1 ANIC) ; Healesville, Dandenong Ranges , 37° 39' S, 145° 32' E, 1–30 October 1968, C. Watts (3 SAMA) ; Holey Plains State Park, firedam on Crooke Track , fine sand and organics at the edge of a small firedam in dry sclerophyll forest, elev. 45 m, 38° 10' S, 146° 20' E, 16 April 2002, N. Porch (87) (7 ANIC) ; Kangaroo Ck. on Springhill Rd. , 5.8 km E Glenlyon, sandy mud along edge of creek (perennial) pools, elev. 510 m, 37° 18' S, 144° 18' E, 31 January 1999, N. Porch (NP 24) (132 ANIC) ; LaTrobe R., Rosedale , 38° 9' S, 146° 34' E, 9 December 1978, not given (2 MVMA) ; Latrobe River at Piedmont , gravel at edge of river at pasture/forest boundary, elev. 255 m, 37° 53' S, 145° 54' E, 1 January 2003, N. Porch & N. Krause (NP 54) (5 ANIC) ; Little Morwell River , 3.8 km NNE Mirboo North, sandy mud and litter accumulation at edge of small creek; dry/moist riparian sclerophyll forest, elev. 165 m, 38° 22' S, 146° 10' E, 3 October 1999, N. Porch (NP 45) (1 ANIC) ; same locality, elev. 165 m, 38° 22' S, 146° 10' E, 24 February 2001, N. Porch & Latrobe Valley Field Naturalists (LVFN) (NP 10) (2 ANIC) ; Little Morwell River, at Ricardo Road, Darlimurla , litter and mud at edge of small creek in dry sclerophyll forest, elev. 150 m, 38° 22' S, 146° 12' E, 9 April 2000, N. Porch (NP 49) (6 ANIC) ; Little River at Bacchus Marsh­Geelong Road , sandy gravel and muddy sand at edge of still pool of perrenial creek in riparian forest remnants, elev. 105 m, 37° 50' S, 144° 23' E, 20 October 1999, N. Porch (36) (5 ANIC) ; Loddon Falls , base of, NE of Glenlyon, sandy gravel at edge of waterfall splashpool in scrubby gorge, elev. 470 m, 37° 16' S, 144° 14' E, 16 March 2001, N. Porch & K. Sniderman (19) (24 ANIC) ; Macalister­Thomson River Jn, NMV Survey Dept. GRES T26 no. 1, 37° 46' S, 146° 40' E, 5 December 1976, not given (1 MVMA) ; Mitta Mitta River , 8 km NW of Dartmouth Dam, 36° 30' S, 147° 26' E, 5 November 1976, A. A. Calder (1 MVMA) ; Morwell River, 6.1 km SSE Boolarra on Morwell River Road ( Apex Park ), willow roots and sandy mud/gravelly mud at edge of small river; under weeping willows, elev. 115 m, 38° 25' S, 146° 18' E, 29 November 1999, N. Porch (NP 38) (5 ANIC) ; Morwell River on Driffield ­ Yinnar Rd., S 43, LaTrobe C. Survey , 38° 19' S, 146° 19' E, 6 December 1978 (3 MVMA) ; Narracan Ck. at Cooks Rd. , 2.3 km NW Thorpdale, in gravel at edge of gravelly riffle of small creek flowing through pasture, elev. 135 m, 38° 16' S, 146° 10' E, 4 February 1999, N. Porch (NP 28) (1 ANIC) ; Narracan Falls , 4.1 km NE Thorpdale, on mud at edge of stream flowing through pasture, elev. 190 m, 38° 16' S, 146° 13' E, 4 February 1999, N. Porch (NP 27) (11 ANIC) ; Sailors Falls, base of, S. of Daylesford , gravelly and sandy margins of pools immediately d/s of waterfall, elev. 590 m, 37° 23' S, 144° 7' E, 16 March 2001, N. Porch & K. Sniderman (14) (92 ANIC) ; Settling Pods Dam, at Junction of Settling Ponds Tk. & Hudbrick Tk., gravelly mud at edge of small dam in dry sclerophyll forest, elev. 260 m, 37° 7' S, 143° 40' E, 9 June 2001, N. Porch (74) (1 ANIC) ; Simpson Ck , 12 km SW Orbost, 27° 47' S, 148° 20' E, 16 January 1997, C. Watts (2 SAMA) ; Spargo Creek, W. of, firedam nr Centre Track , clayey mud at edge of small firedam in pine forest, elev. 705 m, 37° 27' S, 144° 5' E, 17 February 2002, N. Porch (92) (1 ANIC) ; Tarago River, Bellbird Park at old Princes Highway , ex sandy mud and litter in sun along edge of slow flowing river in pasture, elev. 50 m, 38° 5' S, 145° 48' E, 15 January 1999, N. Porch (NP 21) (50 ANIC) ; Toomuc Ck., at Princes Highway, Pakenham , on silty sand and sand along margins of gravelly 'semiurban' creek, elev. 45 m, 38° 4' S, 145° 28' E, 4 February 1999, N. Porch (NP 26) (50 ANIC) ; Werribee River , 11.5 km NNW Ballan, 37° 45' S, 144° 34' E, 22 April 1982, A. J. Boulton (1 ANIC) ; Woori Yallock Ck., at Warburton Highway , ex muddy margins of undercut creek banks near water level; pasture, elev. 110 m, 37° 47' S, 145° 31' E, 23 February 1999, N. Porch (NP 35) (88 ANIC) ; Yarra River at Launching Place, margin of Yarra River on silty fine sand, elev. 115 m, 37° 47' S, 145° 35' E, 23 February 1999, N. Porch (NP 36) (12 ANIC) . Representative specimens to be deposited in CMNH, FMNH, MCZ, NPC, QMBA, and USNM .

Differential Diagnosis. Recognized by the distinctive fringe of setae on the elytral margin, the finely sparsely punctate pronotum, the narrow median groove and nonmicroreticulate foveae, and the elytral intervals wider than the serial punctures. Very similar in dorsal habitus to G. australis (which see), but elytra generally more strongly punctate and have the setae on the intervals more prominent, erect, especially developed on sides and over posterior declivity. Reliable determinations, especially of abraded specimens, will be based on study of the male genitalia, which are similar in being strongly barbed, but differ in shapes of the lobes and especially the shape of the duct, which in G. setosus is long, nearly straight and nearly parallel­sided, and has a rounded apex ( Figs. 2 , 4 ).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.97/ 0.86; head 0.37/0.48; pronotum 0.44/0.67; elytra 1.26/0.86. Form moderately ovate, moderately convex. Color brown, head darker, dorsal reliefs shining.

Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal midlongitudinal fovea confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate; pubescence sparse but rather long on disc, shorter but denser laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length; anterior margin arcuate, with low upturned apicomedian tooth.

Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; arcuate setae, originating from basal sides of pronotum, on top of lateral hyaline border; anterior margin of pronotum slightly arcuate in midregion; each lateral depression with posterior in form of right angle, lateral margin distinctly setose; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, extremely finely sparsely punctate, each puncture with a recumbent yellow seta; median groove shallow, narrow, extending nearly to margins, tapering at ends; anterior foveae well developed, slightly elongate; posterior foveae oblique, linear impressions nearly 1/2 as long as and as wide as median groove; posterolateral angles with indistinct shallow impressions.

Elytra moderately convex on disc, sides nearly vertical in basal 0.5, with six rows of slightly elongate, closely spaced punctures between suture and humeri; each puncture with a decumbent seta that overlaps base of following seta; intervals flat or slightly rounded, width 1.5–2.0x that of punctures; intervals with sparse, erect, moderately long setae, especially developed on sides and over posterior declivity; summit of declivity near posterior 0.66, where elytra are transversely markedly convex; elytral explanate margin very narrow, with fringe of long setae.

Metasternal glabrous area length equal width, oval, convex, shining, with a few punctures. Abdominal ventrites 1–3 and minutely basally 4 with hydrofuge pubescence.

Aedeagus ( Fig. 4 ): Length of main­piece 0.30 mm, length to tip of parameres 0.31 mm; lobes relatively long, in ventral aspect apical width subequal paramere width, each lobe with strong barb near midlength; notches U­shaped, ventral notch slightly deeper and slightly narrower than dorsal notch; ventral notch narrowest width greater than greatest width of lobes; duct rather elongate, nearly parallel­sided, apex slightly enlarged, round in ventral aspect; apical paramere seta elongate, ca. 2x length of next longest seta.

Females have the explanate elytral margin similar to males; the labrum has a very small apicomedian tooth, smaller than that of males.

Etymology. Named to reflect the more prominently setose condition—when compared to members of the similar G. australis .

Distribution. Widely distributed, especially prevalent in eastern ranges, from Victoria to Queensland and on Tasmania (Fig. 75). Currently not known from South Australia.

Figures

FIGURE 2. Gymnochthebius australis. Aedeagus of lectotype.

FIGURE 3. Gymnochthebius setosus, holotype. Dorsal and lateral habitus.

FIGURE 4. Gymnochthebius setosus. Aedeagus of holotype.