Hydraena ascensa, 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 : 88-89

Hydraena ascensa new species

(Figs. 144, 146, 218, 240)

Type Material. Holotype (male): Queensland, Rocky Creek , Kennedy Hwy., 17° 11' S, 145° 27' E, 27 May 1976, E. B. Britton. Deposited in the ANIC . Paratypes (82): Queensland, 15 km NE Mareeba, MDPI intercept trap site No. 25, flight intercept trap, elev. 400 m, 16° 56' S, 145° 32' E, 1 May–14 June 1985, Storey & Halfpapp (1 QPIM) ; 17 km up Mt. Lewis Road , 16° 37' S, 145° 21' E, 1 November 1990, S. DeFaveri & R. Storey (4 QPIM) ; Douglas Shire , Ellis Beach , 30 km N Cairns , 16° 55' S, 145° 46' E, 11 January 1991, D. Larson (2 MCZ) ; Emu Creek, 20 km S. Mareeba , 16° 58' S, 145° 25' E, 20 October 1990, D. Larson (4 MCZ) ; Mt. Cleveland summit, rainforest, pitfall and intercept traps, elev. 500 m, 19° 16' S, 147° 3' E, 23 March–13 May 1991, D. Cook (1 QMBA) ; Mulgrave River, The Fisheries , 17° 11' S, 145° 44' E, 9 November 1990, D. Larson (2 MCZ) ; SW of Tully, pools below Murray Falls , 18° 9' S, 145° 49' E, 23 March 1992, H. & P. Zwick (68 PZC) .

Differential Diagnosis. Similar to H. intraangulata in broad body shape, comparatively truncate elytral apices, dorsal sculpture, including large elytral punctures, and plaque shape; differing therefrom by the smaller size (ca. 1.21 vs. 1.43 mm), the more elongate elytra, and the darker pronotum (Figs. 142, 144). The aedeagi of the two species markedly differ (Figs. 140, 146).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.21/0.53; head 0.21/ 0.30; pronotum 0.32/0.41, PA 0.34, PB 0.38; elytra 0.72/0.53. Head dark brown, margins of clypeus slightly lighter; pronotum light brown with large, brown, diffusely margined macula; elytra dark brown; legs brown; maxillary palpi testaceous, tip not darker.

Head and pronotum microreticulate, dull. Frons punctures slightly less than 1xef; interstices 1–3xpd. Clypeus finely sparsely punctate. Mentum weakly shining, effacedly microreticulate and very finely sparsely punctate; postmentum microreticulate. Genae weakly raised, lacking posterior ridge. Pronotal punctures on disc ca. 2xpd those of frons, interstices 1–3xpd; punctures anteriorly and posteriorly only slightly larger than those on disc, interstices ca. 1xpd; PF1 and PF4 absent; PF2 very shallow; PF3 shallow, broad.

Elytral punctures ca. 2–2.5xpd of largest pronotal punctures; punctures becoming smaller and shallower over posterior declivity. Intervals not raised, shining, width about 1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly truncate, in posterior aspect margins form strong angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2.5/2.5/8/3. P1 laminate; median carina weakly angulate in profile. P2 narrow, l/w ca. 2/1, sides parallel, apex blunt. Plaques located in posterior 1/2 of metaventrite on sides of deep median, narrowly triangular depression; plaques weakly raised, straight, tapering and slightly converging anteriorly. AIS flat, width at arcuate posterior margin ca. 2x P2. Profemur with minute sharp tubercle on medial surface near basal 1/3; protibia very weakly arcuate, gradually increasing in width from base to apex; mesotibia slender, straight; metatibia slender, very weakly arcuate and weakly emarginate on medial margin. Last sternite with small off-center lobe; last tergite with apical, deep, off-center notch, located opposite sternite lobe.

Aedeagus (Fig. 146) main-piece with large basoventral process, also produced on right side apically in step-like lobes, most of right paramere concealed behind main-piece in ventral view; distal piece produced in several lobes, and with moderately long gonopore-bearing flagellum; left paramere very wide, very asymmetrical, ventral margin markedly produced and forming acute angle, with three groups of setae, about thirteen setae in row on ventral lobe (not on margin), about eight apically, and about four on dorsal margin; right paramere narrow basally, markedly widened in distal 1/2, with setae in three groups; large seta on dorsal surface of main-piece. Female last tergite with three incisions, delimiting four lobes, lateral pair much smaller then medial pair, setae slender, tapering; gonocoxite as illustrated (Fig. 218).

Etymology. Named in reference to the series of step-like processes on the aedeagus.

Distribution. Currently known from northeastern Queensland (Fig. 240).