Gymnochthebius probus, 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 probus new species

(Figs. 23, 24, 76)

Type Material. Holotype (male): Australia: Queensland: 31 km NW by N of Longreach , 23° 13' S, 144° 4' E, 10 May 1973, M. S. Upton. Deposited in the ANIC . Paratypes (6): Australia: Northern Territory: Roderick Creek, Gregory N. P., M. V. Light, Operation Raleigh 1986, 15° 38' S, 131° 22' E, 4–6 July 1986, I. Archibald (1 MAGD) ; Queensland: Burunga , at light, 26° 13' S, 150° 1' E, 8 October 1984, I. D. Naumann & J. C. Cardale (1 ANIC) ; South Australia: Cudlee Creek , 34° 50' S, 138° 49' E, 10 November 1996, C. Watts (2 SAMA) ; Victoria: Nathalia , 36° 3' S, 145° 12' E, 18 January 1961, C. Watts (2 SAMA) . Representative specimens to be deposited in MCZ and NPC.

Differential Diagnosis. Recognized by the highly shining dorsum, the finely sparsely punctate head and moderately punctate pronotal reliefs, the metasternal glabrous area length equal width, widest at posterior, flat in posterior 0.5, posterior margin very slightly raised, and, in males, the probe­like apicomedian process of the labrum. Dorsal habitus somewhat resembling the highly shining G. resplendens , but distinguished there from by the narrower and less convex body form, the more coarsely punctate pronotum, the more coarsely punctate elytral series, and the lack of a setal fringe on the lateral elytral margins (Figs. 21, 23). The male genitalia of the two species are quite dissimilar (Figs. 22, 24).

Description. Size (length/width, mm) holotype: body (length to elytral apices) l.67/ 0.71; head 0.37/0.41; pronotum 0.37/0.56; elytra 1.00/0.71. Form moderately ovate, moderately convex. Body and legs light brown, head dark brown, dorsal surface shining.

Head with frons very finely sparsely punctate, very sparsely pubescent; interocular foveae deep; interocular tuberculi distinct; basomedial fovea narrowly confluent with interocular foveae. Frontoclypeal suture deeply impressed, bisinuate. Clypeus midlength less than twice apical width, 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 less than twice length, apicomedian tooth prominent, nearly as long as apical segment of maxillary palpus.

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 angle obtuse, not produced to acute point, lateral margin arcuate, setose; lateral fossulae deep, microsculpture similar to remainder of pronotum; pronotal disc moderately convex, punctures sparse and fine medially, becoming denser and coarser laterally near base, most punctures with a very fine short indistinct seta; median groove deep and wide, extending nearly to margins, tapering at ends; anterior foveae well developed, nearly circular; posterior foveae oblique, 1/2 as long as and as wide and deep as median groove; posterolateral angles with indistinct shallow impressions.

Elytra moderately convex on disc, serial punctures very slightly elongate, closely spaced; intervals rounded, width about equal that of punctures; summit of declivity at about apical 0.6; striae 2 and 3 terminating into 4 at about apical 1/4; elytral explanate margin moderately wide, lacking prominent setae.

Metasternal glabrous area length equal width, widest at posterior, flat in posterior 0.5, posterior margin very slightly raised. Abdominal ventrites 1–3 and basal part of 4 with hydrofuge pubescence.

Aedeagus (Fig. 24): Length of main­piece 0.33 mm, length to tip of parameres 0.36 mm; main­piece slender, lobes relatively short, not barbed but tips very weakly bent; ventral notch roundly V­shaped, widest apically, dorsal notch U­shaped, wider and slightly deeper than ventral notch; duct short, simple, in ventral aspect gonopore on left side; apical paramere seta elongate, much longer than other setae.

Females unknown.

Etymology. Named in reference to the prominent apicomedian process of the male labrum.

Distribution. Currently known from five widely separated localities (each represented by a male) in South Australia, Victoria, Queensland, and Northern Territory (Fig. 76).