Hydraena cubista, Published, 2007

PERKINS, PHILIP D., 2007, A revision of the Australian species of the water beetle genus Hydraena Kugelann (Coleoptera: Hydraenidae), Zootaxa 1489 (1), pp. 1-207 : 112

Hydraena cubista new species

(Figs. 186, 189, 262)

Type Material. Holotype (male): Western Australia, Mining Camp, Mitchell Plateau , 14° 49' S, 125° 50' E, ex. yellow tray, 9–19 May 1983, I. Naumann, J. Cardale. Deposited in the ANIC.

Differential Diagnosis. Recognized by the combination of the nearly hexagonal pronotum, which is widest at midlength, the coarse, dense punctation of the pronotum and elytra, the nearly parallel-sided elytra with wide explanate margin, and the widely separated plaques (Fig. 186). The metatibiae of males are simple. The aedeagus (Fig. 189) shows some similarity in basic form to the aedeagi of H. darwini and H. forticollis (Figs. 190, 191); the pronotum is shaped differently in the three species. The pronotum of H. cubista is similar in shape to that of H. hamifera (Fig. 160), but the two species differ markedly in many other characters, and the aedeagi show no relationship.

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.50/0.66; head 0.24/ 0.37; pronotum 0.38/0.53, PA 0.42, PB 0.45; elytra 0.93/0.66. Head piceous, pronotum and elytra dark brown, legs and palpi brown, tip of palpi not darkened.

Head dull, microreticulate, frons punctures ca. 1.5xef; interstices 0.5–1xpd. Clypeus microreticulate. Mentum weakly shining, microreticulate. Genae weakly raised, lacking posterior ridge. Pronotum widest at midlength. Pronotum densely coarsely punctate, punctures on disc ca. 2–3xpd those of frons, interstices generally narrow walls forming reticulate pattern, slightly sparser on portion of disc; PF1 absent; PF2 small, moderately deep, separated by about width of fovea. PF3 and PF4 shallow, wide.

Elytral nearly parallel-sided, punctures about equal size of largest pronotal punctures. Intervals not raised, shining, width ca. 1xpd, as are interstices between punctures of a row. Explanate margin moderately wide, continuing posteriorly to near apices. Apices in dorsal aspect conjointly rounded to subtruncate, in posterior aspect margins forming angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/3/2. P1 laminate; median carina angulate in profile. P2 moderately narrow, l/w ca. 5/3, sides parallel, apex blunt. Plaques located in posterior 7/10 of metaventrite on sides of deep median elongate subtriangular depression, plaques nearly parallel, wider posteriorly than anteriorly, not raised. No midlongitudinal carina between mesoventral intercoxal process and plaques. Cuticle asperite under hydrofuge pubescence. AIS flat, width at arcuate posterior margin ca. 2x P2. Profemur (male) with small, sharp tubercle on medial surface near basal 1/3; protibia very weakly arcuate, gradually increasing in width from base to apex; mesotibia simple; metatibia slender, straight, without setal brushes. Abdominal apex asymmetrical.

Aedeagus (Fig. 189) main-piece with large, strongly sclerotized process on ventral surface, near base; left paramere large, widest near midlength, with setae in two groups, also with small tubercles near base and in arcuate row along part of ventral margin; right paramere long, with setae in three groups, distal part widened and forming small lobe on ventral margin. Females not yet known.

Etymology. Named in reference to the angular shapes of the pronotum, and the parallel-sided elytra.

Distribution. Currently known only from the type locality in the Mitchell Plateau, northeastern Western Australia (Fig. 262).