Gymnochthebius fumosus, 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 fumosus new species

(Figures 37, 38, 85)

Type Material. Holotype (male): Australia: New South Wales: Sydney , 33° 52' S, 151° 12' E, 1–30 May 1961, C. Watts. Deposited in the SAMA . Paratype: Same data as holotype (1 SAMA) .

Differential Diagnosis. Recognized by the dull, matte dorsum, the abdominal ventrites 1–3 and minutely anteriorly 4 with hydrofuge pubescence, and the dull metasternal glabrous area. The dorsum is much more strongly punctate, especially the elytral series, than that of G. brisbanensis and G. levis , each of which also have the dorsum dull, matte (Figs. 35, 37, 40). The male genitalia show some resemblance to that of G. brisbanensis , but in G. fumosus the lobes are longer and more weakly barbed, the duct weakly arcuate, and the parameres do not extend as far beyond the main­piece (Figs. 36, 38).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.49/ 0.67; head 0.30/0.42; pronotum 0.37/0.54; elytra 0.94/0.67. Form moderately ovate, moderately convex. Dorsum dark brown, effacedly microreticulate or matte, dull.

Head with frons moderately finely punctate, setae small and very sparse; 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. Labroclypeal suture straight in dorsal view, evenly arcuate in anterior view. Labrum width 3x length; anterior margin arcuate, without 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 arcuate in midregion; each lateral depression with posterior angle acute, lateral margin arcuate from anterior angle, then distinctly emarginate in front of posterior angle, with very short indistinct setae; lateral fossulae deep, lacking microsculpture; pronotal disc moderately convex, finely moderately densely punctate, setae very small, indistinct; median groove moderately deep, narrow, extending nearly to margins, tapering at ends; anterior foveae well developed, slightly elongate; posterior foveae oblique, linear impressions 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 deep, closely spaced punctures in shallow striae between suture and humeri; each puncture with short indistinct seta; intervals flat or slightly rounded, width 0.5–1.0x that of punctures; elytral margin without fringe of setae; summit of declivity near slightly past midlength, where elytra are transversely markedly convex; explanate margin very narrow, without fringe of setae.

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

Aedeagus (Fig. 38): Length of main­piece 0.26 mm, length to tip of parameres 0.27 mm; lobes relatively long, moderately strongly barbed; notches U­shaped, ventral notch nearly parallel­sided, dorsal notch slightly shallower than ventral notch; duct weakly arcuate just before rounded apex; several paramere setae broken on holotype.

Females unknown.

Etymology. Named in reference to the dull, "smoky" dorsum.

Distribution. Currently known only from the type locality, Sydney (Fig. 85).