Hydraena millerorum, 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 : 20-21

Hydraena millerorum new species

( Figs. 19 , 24 , 261)

Type Material. Holotype (male): Victoria, Traralgon Creek, 0.2 km N ' Hogg Bridge', 5.0 km NNW Balook , ex wet litter on bank and in water, elev. 170 m, 38° 24' S, 146° 32' E, 13 January 1999, N. Porch (NP 10). Deposited in the ANIC . Paratypes (9): New South Wales, Headwaters of Nullica River , headwater stream, 37° 4' S, 149° 47' E, 10 June 1999, J. & R . Miller (site 659) (2 ANIC); same locality, 37° 4' S, 149° 47' E, 24 June 1999, J. & R . Miller (site 659) (2 ANIC); Unnamed creek drains into Crawleys Creek , 36° 56' S, 149° 43' E, 13–22 June 1999, J. & R . Miller (site 731) (3 ANIC); Unnamed creek drains into Nungatta Creek , 36° 7' S, 149° 29' E, 12 February 2000, J. & R . Miller (site 566b) (1 ANIC) ; Victoria, Traralgon Creek, 0.2 km N ' Hogg Bridge', 5.0 km NNW Balook , ex wet litter on bank and in water, elev. 170 m, 38° 24' S, 146° 32' E, 13 January 1999, N. Porch (NP 10) (1 ANIC) .

Differential Diagnosis. Externally most similar to H. porchi ; differing therefrom by the sparser and coarser dorsal punctation, the slightly larger elytra, and the more deeply impressed pronotal foveae PF2 ( Figs. 14 , 19 ). The most reliable determinations will be based on examination of the aedeagi of the two species ( Figs. 23, 24 ).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.52/0.61; head 0.25/ 0.35; pronotum 0.37/0.47, PA 0.40, PB 0.41; elytra 0.93/0.61. Head piceous; pronotum and elytra dark brown, pronotum lighter narrowly on margins; legs brown; palpi light brown, tip not darkened.

Frons punctures ca. 1xef; interstices shining, 1–3xpd. Clypeus microreticulate laterally, shining and finely sparsely punctate medially. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc slightly larger than those of frons, interstices shining, 1–2xpd anteriorly and posteriorly, 2–4xpd on disc; PF1 and PF4 absent; PF2 moderately deep, oblique; PF3 shallow, broad.

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

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/2/6/5. P1 laminate; median carina angulate in profile. P2 narrow, l/w ca. 5/2, sides weakly converging, apex blunt. Plaques located in posterior 1/2 of metaventrite on sides of deep median depression, each plaque tapering anteriorly. AIS flat, width at arcuate posterior margin 2–3x P2. Protibia (male) widened to about midlength, then markedly excavate, a prominent spine at base of excavation; meso- and metatibiae slender, metatibia weakly emarginate on medial margin over distal 2/3. Last sternite symmetrical or nearly so; last tergite very weakly emarginate.

Aedeagus ( Fig. 24 ) main-piece with distal extended part arcuate, continuing slightly above and beyond distal piece, distinctly widened subapically, extreme tip slightly widened and bearing minute tubercles; distal piece with two lobes, the right larger than the left, the left with a minute lobe near the base (ventral view), the right with the apex blunt and widened (lateral view); left paramere slender, very weakly sinuate, about 1/3 longer than right paramere, with cluster of about four setae on inner margin near apex; right paramere straight except angled at base of widened tip, with setae in two groups, the apical group about four times as long as the other group. Female last tergite with apicomedian incision delimiting two lobes, setae slender, tapering.

Etymology. Named in honor of Jan and Robert Miller of New South Wales, who collected many of the specimens.

Distribution. Currently known from Victoria and southern New South Wales (Fig. 261).

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.