Gymnochthebius resplendens, 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 resplendens new species

(Figures 21, 22, 76)

Type Material. Holotype (male): Australia: Queensland: nr. Westcott Plain, Bunya Mts. Nat. Pk., 26° 52' S, 151° 34' E, 6–7 October 1984, I. D. Naumann & J. C. Cardale. Deposited in the ANIC . Paratypes (50): Australia: New South Wales: Bogan River , 33° 0' S, 148° 2' E, 1–30 October 1933, J. Armstrong (2 AMSA) ; Darling River , 29° 57' S, 146° 18' E, 1 May 1925, H. J. Carter (3 ANIC) ; Darling River , shore washing, 23° 11' S, 141° 42' E, 1 October 1982, Endrödy­Younga (AU­24) [labels read Darling River, but based on geocodes this would be the Diamantinna River] (23 TMSA) ; Fowlers Gap , shore washing, 30° 55' S, 141° 36' E, 3 October 1982, Endrödy­Younga (AU­25) (13 TMSA) ; Wilcannia, 5 km E of, at Darling River , sandy mud at edge of river, elev. 70 m, 31° 34' S, 143° 25' E, 1 September 2000, Rhys Porch (5) (6 ANIC) ; Queensland: Biloela , 24° 24' S, 150° 30' E, 7 September 1972, H. E. Hinton (1 ANIC) ; Broken River , 50 miles W of Mackay, 19° 32' S, 144° 54' E, 30 November 1968, S. Misko (1 ANIC) . Representative specimens to be deposited in MCZ, NPC, QMBA, and SAMA .

Differential Diagnosis. Recognized by the highly shining dorsum, the very finely sparsely punctate pronotal disc without perceptible setae, the large and deep pronotal foveae with smooth, gradually sloping margins, the relatively narrow median groove, the elytral intervals about twice as wide as the serial punctures, and the very slightly acuminate elytral apices. Distinguished from G. australis and G. setosus by the body form, the greatly reduced dorsal setae, and the male genitalia ( Figs. 1 , 3 , 21).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.60/ 0.75; head 0.33/0.44; pronotum 0.37/0.56; elytra 1.04/0.75. Form moderately ovate, moderately convex. Color brown, head darker, dorsum markedly shining.

Frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basal impression confluent with interocular foveae, with very fine midlongitudinal line. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength 0.5 apical width, very sparsely punctate. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width twice length; anterior margin arcuate, with low upturned apicomedian tooth. Maxillary palpomere 3 about twice length of 4.

Pronotum shining, very finely sparsely punctate; lateral hyaline border well developed, origin at base of lateral depression, arcuate to posterior angles, very narrow around posterior margin; anterior margin of pronotum evenly bisinuate; each lateral depression with posterior angle slightly obtuse, lateral margin with fringe of short setae; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, extremely finely sparsely punctate, each puncture with a minute nearly imperceptible seta; median groove moderately deep, narrow, extending nearly to margins, tapering at ends, sides rather abrupt compared with gradually sloping foveae; anterior foveae well developed, oval, margins gradually sloping; posterior foveae oblique, oval, nearly 1/2 as long as and twice as wide as median groove; posterolateral angles with indistinct shallow impressions.

Elytra moderately convex on disc, sides sloping, not vertical, in midregion, with six rows of slightly elongate, closely spaced punctures between suture and humeri; punctures on disc without perceptible setae, setae laterally and over posterior declivity very short, not attaining adjacent puncture; intervals flat or slightly rounded, width 2.0–2.5x that of punctures; intervals over posterior declivity with very sparse, decumbent setae; summit of declivity near 0.66 length, where elytra are transversely markedly convex; elytral explanate margin very narrow, with fringe of moderately long setae.

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

Aedeagus (Fig. 22): Length of main­piece 0.26 mm, parameres attaining tips of lobes; lobes relatively long, markedly arcuate on dorsal surface, each with a small subapical barb on ventrolateral surface; notches widest apically, dorsal notch U­shaped, wider and shallower than V­shaped ventral notch; duct slightly enlarged apically and produced in tiny point; apical paramere seta elongate, ca. 2x length of next longest seta.

Females have the elytral explanate margin similar to that of males; the anterior margin of the labrum sometimes has a minute tooth, smaller than that of males.

Etymology. Named in reference to the strongly shining dorsum.

Distribution. Currently known from widely separated localities in New South Wales and Queensland (Fig. 76).

Figures

FIGURE 1. Gymnochthebius australis, lectotype. Dorsal and lateral habitus.

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