Gymnochthebius notalis (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 notalis (Deane) new combination

( Figures 11 , 12 , 73)

Ochthebius notalis Deane 1933: 24 .

Type Material. Holotype (male): Australia: Western Australia: Bunbury [labels: " Type "; " Ochthebius notalis Deane. (descr. publishd.) det. C.Deane. p. 24 fig. 7"]. Deposited in the UQIC.

Differential Diagnosis. Recognized by the coarsely densely punctate pronotum, the narrow median groove, the comparatively narrow weakly convex elytra, and the elytral intervals wider than the shallowly striate­impressed elytral series. This species shows some superficial resemblance to G. lividus , but is smaller (ca. 1.67 mm vs. 2.00 mm), differently colored, more coarsely punctate, and does not have an anterior extension of the pronotal lateral hyaline border. The male genitalia of the two species are very different ( Figs. 10 , 12 ).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.67/ 0.71; head 0.33/0.44; pronotum 0.40/0.58; elytra 1.12/0.71. Form elongate oval, weakly convex. Color dark brown to black (holotype teneral, brown), dorsal reliefs moderately shining.

Frons very finely sparsely punctate on median relief, more coarsely punctate laterally, 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, moderately coarsely densely punctate, especially in basal 0.5; pubescence sparse and short. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 2.5x length; anterior margin arcuate, with very 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; anterior margin of pronotum slightly produced in midregion; each lateral depression with posterior in form of right angle, lateral margin with fringe of short arcuate setae; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, moderately coarsely densely punctate, each puncture with a very indistinct recumbent seta; median groove deep, narrow, not attaining anterior or posterior margins, tapering at ends; anterior foveae deep, small; posterior foveae oblique, linear impressions nearly 1/2 as long as and nearly twice as wide as median groove; posterolateral angles without indistinct shallow impressions.

Elytra transversely weakly convex on disc, longitudinally nearly flat, with six rows of closely spaced punctures in shallow striae between suture and humeri; each puncture with a decumbent or recumbent seta that overlaps base of following seta; intervals flat or slightly rounded, width 1.0–1.5 that of punctures; intervals lacking prominent setae; elytra sides weakly arcuate, margin lacking fringe of setae; explanate margin narrow; posterior declivity gradual, summit slightly behind midlength; elytra narrowed slightly preapically, apices conjointly sharply rounded.

Metasternal glabrous area length equal width, oval in females, widest behind midlength in males, shining, nearly flat. Abdominal ventrites 1–3 and basally 4 with hydrofuge pubescence.

Aedeagus ( Fig. 12 ): Length of main­piece 0.26 mm, length to tip of parameres 0.30 mm; main­piece wide in ventral aspect, slightly narrowed near midlength in oblique aspect; lobes relatively long, sharply rounded apically, strongly barbed; notches U­shaped, ventral notch deeper than dorsal notch; duct asymmetrical in ventral aspect, truncate at apex in oblique aspect; apical paramere seta elongate, ca. 2x length of next longest seta.

Females have the explanate elytral margin very slightly if at all wider than that of males; the anterior margin of the labrum is arcuate.

Distribution. Currently known from southern and western Western Australia (Fig. 73).

Material Examined (157): Australia: Western Australia: 20 km EbyN of Esperance , at light, 33° 50' S, 122° 6' E, 8 November 1977, J. F. Lawrence (2 ANIC) ; Belmont, Perth , 31° 33' S, 115° 41' E, 3 January 1954, H. Demarz (4 FMNH) ; Bridgetown , 34° 1' S, 116° 0' E, 9 November 1931, P. J. Darlington (4 MCZ) ; Bunbury [no date], 33° 20' S, 115° 38' E, Whitlock (4 AMSA, 24 UQIC) ; Burns Beach , 31° 43' S, 115° 43' E, 27 October 1969, D. D. Giuliani (4 ANIC) ; Esperance , 33° 51' S, 121° 53' E, 1–30 March 1972, P. Zwick (19 MCZ) ; Geraldton , 28° 46' S, 114° 36' E, 1–30 October 1931, P. J. Darlington (1 MCZ) ; L. Clifton, 32° 50' S, 115° 43' E, 1–30 March 1972, P. Zwick (13 MCZ) ; L. Walyungup, 32° 20' S, 115° 46' E, 1–30 March 1972, P. Zwick (3 MCZ) ; Murchison R., 27° 49' S, 114° 41' E, 28 April 1971, E. F. Riek (1 ANIC) ; Murchison River , 24k N Binnu, river, 27° 49' S, 114° 40' E, 18 May 2001, C. H. S. Watts (13 SAMA) ; Parry’s Inlet turnoff on Denmark Rd. , 14 mi. E of Denmark, roadside pond, 35° 1' S, 117° 9' E, 9 November 1969, E. B. Britton (50 ANIC) ; Preston River [no date], 33° 19' S, 115° 40' E, Whitlock (9 UQIC) ; Stream on road to Williams Bay , 24 September 1965, E. Britton (4 ANIC) ; Yanchep. , 32 mls. N Perth, 31° 33' S, 115° 41' E, 13–23 November 1935, R. E. Turner (1

BMNH). Representative specimens to be deposited in CMNH, FMNH, MCZ, NPC, QMBA, and WAMP.

Figures

FIGURE 10. Gymnochthebius lividus. Aedeagus of specimen from Victoria: Eaglemont, Yarra Flats.

FIGURE 11. Gymnochthebius notalis, holotype. Dorsal and lateral habitus.

FIGURE 12. Gymnochthebius notalis. Aedeagus of holotype.