Gymnanthelius maxipunctus, Perkins, Philip D., 2004

Perkins, Philip D., 2004, A revision of the Australian endemic water beetle genus Gymnanthelius Perkins (Coleoptera: Hydraenidae), Zootaxa 585, pp. 1-39 : 22-23

Gymnanthelius maxipunctus new species

( Figures 9 , 17 , 25 )

Type Material. Holotype (male): New South Wales [no other locality data]; “Had mixed with australis; Griffith Collection Id. by A. M. Lea.”; deposited in the SAMA. Paratypes (8): Australian Capital Territory, Paddy's River, 35° 29' S, 148° 59' E, 16 January 1969, J. Balfour­Browne — (1 BMNH); Queensland, Dayboro, 2 km S, in moist soil, dry river bed, 27° 13' S, 152° 50' E, 12 October 1991, T. Gush — (1 ANIC); Conondale, Mary River, edge/rocks, 26° 44' S, 152° 43 E, 12 September 1993, L. Hill — (1 ANIC); New South Wales, 1.6 km W Laurieville, Jerrabatgulla Creek, 2141 ft., 35° 38' S, 149° 36' E, 4 January 2001, W. D. Shepard — (2 MCZ); Oberon, 27.5 km NW, from creek bank, 33° 31' S, 149° 43' E, 17 November 1991, T. Gush — (3 ANIC).

Diagnosis. Recognized by the strongly punctate dorsum, the random elytra punctures, except for one row along explanate margin, and the low tumidity over the posterior declivity of the elytron. Most similar to G. t u n i c u s, but distinctly differing in more convex form, much smaller size (ca. 1.67 mm vs. 2.08 mm), more coarsely densely punctate pronotum, color, and aedeagal structure ( Figs. 16, 17 ).

Description. Holotype 1.67 x 0.82; head length 0.37, width 0.46; pronotum midlength 0.48, maximum width 0.63 just behind anterior angles; elytra length 1.04, maximum width 0.82. Form moderately ovate, transversely quite convex. Dorsum very dark brown to piceus.

Eyes moderately large, in dorsal aspect 9 convex facets in longest series. Clypeus and frons coarsely densely punctate, most punctures separated by narrow walls, without discernable setae. Clypeus width twice length, anterior angles acuminate. Frons interocular foveae deeply impressed, each as wide as disc separating them; not confluent posteriorly with basomedial longitudinal weak carina behind median relief. Ocelli very indistinct. Labrum short, almost hidden beneath clypeus in habitus view, length:width as 4:14, anteriorly produced in two weakly reflexed lobes separated by U­shaped median emargination, each lobe slightly longer than last maxillary palpomere, setae distinct on disc, laterally forming narrow fringe.

Pronotum anterior margin nearly evenly arcuate, only very weakly emarginate in front of lateral fossulae; hyaline border very narrow except wider in front of lateral fossulae. Lateral depression four times as wide anteriorly as posteriorly, side emarginate before tooth­like posterior angle. Lateral hyaline border with anterior extreme nearly attaining anterior angles, margin weakly arcuate, very narrow along sides, widest just behind lateral depression, in dorsal aspect margin oblique to midline. Lateral fossulae deep, inner margin abrupt, outer margin obsolete; without anterior or posterior pit. Disc transversely quite convex, gradually widening from anterior to slightly beyond middle, then sides converging but only very slightly so to base; densely coarsely punctate, punctures c. 1.5– 2 x eye facet, interstices very narrow, shining. Median groove deep, mcr., rather narrow, very slightly constricted in middle, slightly wider in anterior than posterior 0.5, each end tapering and not attaining respective hyaline border. Anterior foveae shallow, punctate, each wider than median groove at same level, separated from median groove by c. 1x fovea width, margins ill­defined. Posterior foveae absent or location only faintly indicated by slightly denser punctures.

Elytra widest at middle, sides regularly arcuate; explanate margin narrower than metatibia, declivous, surface flat, origin at anterolateral angles, becoming obsolete near posterior 0.2, without discernable setae. Apices conjointly rounded, in female conjointly sharply rounded or subtruncate. Transversely quite convex, lateral and posterior declivity abrupt, surface slightly tumid over posterior declivity. Elytral punctures random, very large, c. 2– 3 x size of largest pronotal punctures, separated by narrow walls. Each puncture bearing short subdecumbent seta.

Metasternal glabrous area large, almost circular, mcr., dull, finely punctate. Ventrites 1–4 with hydrofuge pubescence.

Aedeagus: Length 0.30mm.; mainpiece relatively wide compared with length (as 4.5:14), apex asymmetrical, blunt; internal tube distal part relatively wide, irregularly oval; parameres with distal pair of setae relatively thickened, longer seta of each pair distinctly sinuate ( Fig. 17 ).

Etymology. Named in reference to the coarse and dense dorsal punctation.

Distribution. Currently known from the Australian Capital Territory, New South Wales and southern Queensland ( Fig. 25 ).

Figures

FIGURE 9. Gymnanthelius maxipunctus holotype. Dorsal and lateral habitus.

FIGURES 14 – 17. Gymnanthelius aedeagi. — 14. G. hieroglyphicus (specimen from NSW, Khancoban). — 15. G. po rc h i (holotype). — 16. G. tu nic u s (holotype). — 17. G. maxipunctus (holotype).

FIGURES 22 – 25. Gymnanthelius geographical distributions. — 22. G. opacicollis. — 23. G. hieroglyphicus. — 24. G. t u n i c u s. — 25. G. maxipunctus.