Gymnochthebius levis (Deane) 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 levis (Deane) new combination

(Figures 40, 41, 83)

Ochthebius levis Deane, 1933: 22 .

Type Material. Holotype (female): Australia: Victoria: Echuca [labels: "Echuca.Vic 3.1. 32 F. E. Wilson "; " Type 2274"]. Deposited in the MVMA.

Differential Diagnosis. Recognized by the small size (ca. 1.40 mm), the entirely dull, pruinose dorsum, the elytral fringe of setae, the very small, slightly elongate elytral serial punctures, and the comparatively wide elytral intervals. Easily differentiated from G.brisbanensis , which is also pruinose dorsally, by the smaller size and the fringe of setae on the elytral lateral margins. The male genitalia of the two species are quite distinct (Figs. 36, 41).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.40/ 0.64; head 0.28/0.40; pronotum 0.36/0.56; elytra 0.96 /0.64. Form moderately ovate, moderately convex. Color brown, head slightly darker. Pronotum and elytra dull, pruinose.

Head with frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep, Y­shaped; interocular tuberculi well developed, transverse; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength twice apical width, shiny, very sparsely punctate; pubescence very sparse on disc, slightly more developed laterally. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length, anterior margin arcuate, with apicomedian small tooth.

Pronotum lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum slightly produced in midregion; each lateral depression a single lobe, upturned at anterior, excavate at posterior, and bordered laterally with decumbent setae; lateral fossulae deep, microsculpture similar to remainder of pronotum; pronotal disc moderately convex, extremely finely sparsely punctate, dull but without apparent microreticulation (pruinose); foveae with similar surfaces; median groove shallow, very narrow, extending nearly to margins, tapering at ends; anterior foveae shallow, small, closer to lateral fossulae than to median groove; posterior foveae oblique, linear impressions nearly 1/2 as long as and similar in width to median groove; posterolateral angles with distinct shallow impressions.

Elytra moderately convex on disc, dull similar to pronotum, with six rows of shallow punctures in very shallow striae between suture and humeri; intervals flat, width 4x that of punctures, punctures longer than wide, separated serially from each other by about puncture length; summit of declivity near apical one­third; explanate margin narrow, with fringe of setae which extend out from margin about 3x that of lateral setae of pronotum.

Prosternum with midlongitudinal carina. Metasternal glabrous area large, shiny, length equal width, oval. Abdominal ventrites 1–2 and anterior margin of 3 with hydrofuge pubescence.

Aedeagus (Fig. 41): Length of main­piece 0.23 mm, length to tip of parameres 0.26 mm; lobes relatively long and slender, barbed subapically and apically; ventral notch deeper than dorsal notch; duct widened apically; all paramere setae short.

Females have the elytral explanate margin similar to that of males; the labrum has a minute apicomedian tooth.

Distribution. Currently known from Victoria (Fig. 83).

Remarks. Deane's figure 4 (1933: 23) is misleading with regard to the shape of the pronotum as the lateral hyaline borders are not drawn. Also, the pronotum is drawn at a deflexed angle which makes it appear more transverse.

Material Examined (12): Australia: Victoria: 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° 70' E, 9 June 2001, N. Porch (74) (3 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) (1 ANIC) ; ' Yarra Flats', Eaglemont ( Melbourne suburb), ex mud at edge of small drying 'billabong' in parklands, elev. 15 m, 37° 46' S, 145° 4' E, 26 February 1999, N. Porch (NP 37) (8 ANIC) . Representative specimens to be deposited in MCZ, NPC, and SAMA .