Hydraena tenuisoror, 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 : 21-22

Hydraena tenuisoror new species

( Figs. 20 , 25 , 260)

Type Material. Holotype (male): Australian Capital Territory, Wombat Creek , 6 km NE of Piccadilly Circus, flight intercept window/ trough trap, elev. 750 m, 35° 19' S, 148° 51' E, 1–30 August 1984, Weir, Lawrence, Johnson. Deposited in the ANIC . Paratypes (6): Australian Capital Territory, Same locality as holotype, 1–30 March 1984, Weir, Lawrence, Johnson (1 ANIC) ; same locality, elev. 750 m, 35° 19' S, 148° 51' E, 1–30 March 1985, Weir, Lawrence, Johnson (1 ANIC) ; same locality, elev. 750 m, 35° 19' S, 148° 51' E, 1–30 October 1985, Weir, Lawrence, Johnson (1 ANIC) ; Victoria, Mitta Mitta River , 8 km NW of Dartmouth Dam, 36° 30' S, 147° 26' E, 5 November 1976, A. A. Calder (3 MVMA) .

Differential Diagnosis. Externally most similar to H. porchi ( Figs. 14 , 20 ); differing therefrom by the slightly sparser dorsal punctation, and the slightly larger elytra. Reliable determinations will be based on examination of the aedeagi of the two species ( Figs. 23, 25 ).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.49/0.61; head 0.25/ 0.35; pronotum 0.36/0.47, PA 0.38, PB 0.41; elytra 0.88/0.61. Dorsum dark brown, marginal areas of pronotum slightly lighter than disc, legs brown, maxillary palpi testaceous, tip of last palpomere not darker.

Frons punctures ca. 1xef; interstices weakly shining, 1–2xpd. Clypeus microreticulate laterally, finely sparsely punctate medially. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc ca. 1.5xpd those of frons, interstices shining, ca. 2–4xpd; punctures larger and deeper anteriorly and posteriorly, interstices ca. 1xpd; PF1 absent; PF2 shallow, oblique; PF3 moderately deep, broad; PF4 very shallow. Anterior margin of pronotum broadly emarginate.

Elytral punctures about equal size of largest pronotal punctures. Intervals not raised, shining, width about 1–1.5xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly moderately sharply rounded, in posterior aspect margins form shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/2/7/4. P1 laminate; median carina angulate in pro- file. P2 narrow, l/w ca. 5/2, sides parallel, apex blunt. Plaques converging and narrowly separate anteriorly, not raised, located on each side of deep subtriangular depression. No midlongitudinal carina between mesoventral intercoxal process and plaques. AIS flat, width at arcuate posterior margin ca. 2x P2. Profemur (male) with tiny tubercle on medial surface near distal 1/3; protibia gradually widened to near distal 1/3, then excavate on inner surface, small spine at beginning of excavation; mesotibia simple; metatibia nearly straight, very weakly emarginate on inner surface over distal 3/4. Last tergite with apical, small, very slightly off-center concavity.

Aedeagus ( Fig. 25 ) main-piece with distal extended part arcuate, tapering to a fimbriate tip, continuing above and beyond distal piece; distal piece with two lobes, the right slightly larger than the left, the left with two weak enlargements on left margin (ventral view), the right lobe with apex blunt and expanded (lateral view); left paramere slender, almost straight, about twice as long as right paramere, with cluster of about five setae on inner margin at apex; right paramere very slightly arcuate, with setae in two groups at widened apex, all setae about equal in length. Female last tergite with apicomedian incision delimiting two lobes, setae slen- der, tapering.

Etymology. "Thin sister"; named in reference to the slender body form, compared with H. latisoror and H. williamsensis .

Distribution. Currently known from Victoria and the Australian Capital Territory (Fig. 260).

Figures

FIGURES 19–22. Hydraena, dorsal and lateral habitus of holotypes. —19. H. millerorum. —20. H. tenuisoror. —21. H. latisoror. —22. H. williamsensis.

FIGURES 23–26. Aedeagi of holotypes. —23. H. porchi. —24. H. millerorum. —25. H. tenuisoror. —26. H. latisoror.

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