Hydraena innuda, 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 : 18-19

Hydraena innuda new species

( Figs. 13 , 17 , 259)

Type Material. Holotype (male): Western Australia, Mitchell Plateau , 16 mi. N Amax Camp, in spring pool drainage over basalt road, 14° 46' S, 125° 47' E, 21 October 1976, J. Kethley (112). Deposited in the ANIC . Paratypes (9): Western Australia, 14 km SbyE Kalumburu Mission, CALM Site 4/3 [Western Australian Department of Conservation and Land Management], at light, open forest, 14° 25' S, 126° 40' E, 3–6 June 1988, T . A. Weir (3 ANIC); Mitchell Plateau , 16 mi. N Amax Camp, in spring pool drainage over basalt road, 14° 46' S, 125° 47' E, 21 October 1976, J. Kethley (112) (2 ANIC); Synnot Ck., CALM Site 25/1 [Western Australian Department of Conservation and Land Management], at light, closed forest margin, 16° 31' S, 125° 16' E, 17–20 June 1988, T . A. Weir (4 ANIC) .

Differential Diagnosis. Similar in small size and color to H. magnetica and H. miniretia ; differing therefrom by the narrower body form, the nearly quadrate pronotum, and the lack of plaques ( Figs. 11–13 ). The aedeagus of H. innuda differs distinctively from that of the compared species ( Figs. 15–17 ).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.16/0.48; head 0.19/ 0.30; pronotum 0.28/0.37, PA 0.33, PB 0.34; elytra 0.68/0.48. Head and pronotal disc piceous, margins of pronotum and elytra dark brown, legs and maxillary palpi brown.

Frons finely sparsely punctate, punctures distinctly smaller than 1xef; interstices strongly shining, 2– 6xpd. Clypeus shining and nearly impunctate in midline, finely sparsely punctate laterally. Mentum and postmentum dull, microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc ca. 1xef, interstices shining, 2–3xpd, punctures slightly denser anteriorly and posteriorly, interstices ca. 1xpd; PF1 and PF4 absent; PF2 very shallow, almost absent; PF3 shallow.

Elytral punctures about equal size of largest pronotal punctures. Intervals not raised, shining, width about 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins form very weak or no angle with one another.

Plaques absent. P1 laminate; median carina angulate in profile. P2 moderately narrow, l/w ca. 2/1, sides parallel, apex blunt. Metaventral depression deep. AIS flat, width at arcuate posterior margin slightly less than 2x P2. Legs simple, tibiae slender. Last sternite and last tergite simple, symmetrical.

Aedeagus ( Fig. 17 ) main-piece in ventral view only slightly wider distally than at base, in lateral view markedly angulate; right side of main-piece produced in large process; distal piece comparatively simple, with dorsal lobe covered in small tubercles; parameres simple, about equal in length, setae rather long, not divided into distinct groups. Female last tergite with apicomedian incision delimiting two lobes, setae slender, tapering.

Etymology. Named in reference to the lack of plaques.

Distribution. Currently known from northern Western Australia (Fig. 259).

Figures

FIGURES 11–14. Hydraena, dorsal and lateral habitus of holotypes. —11. H. magnetica. —12. H. miniretia. —13. H. innuda. —14. H. porchi.

FIGURES 15–18. Aedeagi of holotypes. —15. H. magnetica (after Zwick 1977). —16. H. miniretia. —17. H. innuda. —18. H. converga.