Hydraena cultrata, 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 : 102-103

Hydraena cultrata new species

(Figs. 69, 173, 239)

Type Material. Holotype (male): New South Wales, Bruxner Flora Reserve , ex. leaf/twig debris in streambed pools, 30° 15' S, 153° 6' E, 28 January 1998, P. D. Perkins. Deposited in the QMBA . Paratypes (72): New South Wales, Same data as holotype (22 MCZ) ; Dorrigo N. P., Rosewood Creek, upstream from Coachwood Falls , ex. gravel/sand stream bank, elev. 650 m, 30° 22' S, 152° 40' E, 26 January 1998, P. D. Perkins (42 MCZ) ; Dorrigo N. P., Sassafras Creek , upstream from Casuarina Falls , silty gravel bank in shade, elev. 650 m, 30° 22' S, 152° 40' E, 27 January 1998, P. D. Perkins (5 MCZ) ; Queensland, 30 km NE Brisbane, Mt. Nebo Road, Pond, ca. 200 m, Sclerophyll forest , elev. 540 m, 27° 24' S, 152° 48' E, 21 August 2004, M. A. Jäch (AU 1) (1 NMW) ; 90 km SW Brisbane, 40 km NE Warwick , 28° 3' S, 152° 22' E, 26 August 2004, M. A. Jäch (AU 17) (2 NMW) .

Differential Diagnosis. Similar to H. bidefensa in color pattern (Figs. 66, 173), with testaceous pronotum contrasting with the dark brown head and elytra, and the widely separated plaques; differing therefrom by the smaller size (ca. 1.25 vs. 1.50 mm), the slightly more transverse pronotum (w/l ca. 1.31 vs. 1.24), the slightly less shining dorsum, and the arcuate plaques. The aedeagi of the two species distinctively differ (Figs. 69, 70).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.25/0.51; head 0.19/ 0.30; pronotum 0.32/0.42, PA 0.34, PB 0.36; elytra 0.74/0.51. Head dark brown, lateral areas of clypeus lighter; pronotum, labrum, maxillary palpi and legs testaceous; elytra brown.

Frons effacedly microreticulate, weakly shining; punctures ca. 1xef; interstices 3–5xpd. Clypeus microreticulate. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc only slightly, if at all, larger than those of frons; interstices shining, on disc 1–4xpd, anteriorly and posteriorly 1–2xpd; PF1 and PF4 absent; PF2 very shallow, almost absent; PF3 shallow, broad.

Elytral punctures slightly smaller than largest pronotal punctures. Intervals not raised, shining, width about 2xpd, as are interstices between punctures of a row. Apices in dorsal aspect subtruncate, in posterior aspect margins form strong angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2.5/1/6/4. P1 laminate; median carina angulate in profile. P2 moderately narrow, l/w ca. 2/1, sides parallel, apex blunt. Plaques narrow, arcuate, raised, becoming weakly carinate at posterior extreme, located on sides of deep median depression. AIS flat, width at arcuate posterior margin 2x P2. Protibia slightly widened on inner margin over apical 1/4; mesotibia and metatibia slender, simple. Penultimate tergite asymmetrical, produced in small apical lobe on right side. Last sternite very slightly asymmetrical, apex produced in small rounded point; last tergite with off-center, deep concavity.

Aedeagus (Fig. 69) main-piece with large lobe on right side, gradually increasing in size to rounded apex; distal piece with distinctive, knife-shaped apex that extends beyond gonopore bearing flagellum; left paramere shorter and wider than right, setae in two groups; right paramere slender, nearly straight, setae in one group at weakly widened apex. Female last tergite with three incisions, delimiting four lobes, central pair largest, margin lateral to lobes slightly emarginate, setae slender, tapering; gonocoxite as illustrated (Fig. 221).

Etymology. Named in reference to the knife-shaped apex of the aedeagus.

Distribution. Currently known from northern New South Wales and southern Queensland (Fig. 239).