Hydraena supina, Perkins, 2011

Perkins, Philip D., 2011, New species (130) of the hyperdiverse aquatic beetle genus Hydraena Kugelann from Papua New Guinea, and a preliminary analysis of areas of endemism (Coleoptera: Hydraenidae) 2944, Zootaxa 2944 (1), pp. 1-417 : 39-40

Hydraena supina , new species

( Figs. 47 , 49, 453 )

Type Material. Holotype (male): Eastern Highlands Province: Wanitabi Valley, nr. Okapa , ex muddy gravel banks of small shaded stream, 1524 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 177a) ( NHM) . Paratypes (102): Eastern Highlands Province: Headwaters of Fio River , 0.5 km downstream of river crossing on Herowana / Oke Lookout path, ca. 4.5 km N of Herowana airstrip, washed from margins of riverside still water pools in rainforest; gravel and cobble dominated microhabitats, but some muddy, 1500 m, 6° 35' S, 145° 11' E, 29 v 2004, N. Porch (1 ANIC) ; Wanitabi Valley , nr. Okapa, ex muddy gravel banks of small shaded stream, 1524 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 177a) (10 NHM) ; Western Highlands Province: Kundum , 1400 m, 5° 16.096' S, 144° 27.869' E, 3 iii 2007, Kinibel ( PNG 142) (4 ZSM) ; Mondmill , 5 km SE Minj, small pools near creek, 1740 m, 5° 56.801' S, 144° 39.898' E, 12 vi 2006, John ( PNG 77) (2 ZSM) ; Simbai , 1800–2000 m, 5° 14.276' S, 144° 28.741' E, 1 iii 2007, Kinibel ( PNG 138) (55 MCZ, NHM, NMW, PNG, ZSM); Simbai , Ineng River , 2000 m, 5° 14.943' S, 144° 32.818' E, 27 ii 2007, Kinibel ( PNG 135) (9 MCZ, NHM, NMW, PNG, ZSM); Simbai, Kairong River, 1850 m, 5° 14.84' S, 144° 28.457' E, 2 iii 2007, Kinibel ( PNG 139) (21 MCZ, NHM, NMW, PNG, ZSM) .

Differential Diagnosis. The habitus is somewhat similar to that of H. lassulipes ( Figs. 46 , 47 ); differing therefrom and from other members of the Jubilata group by the shape of the pronotum, having the sides rather distinctively emarginate between the anterior angles and the widest part; differing additionally by the comparatively large size (ca. 1.90 mm). The metasternal plaques and the slightly arcuate male metatibiae are quite similar to those of H. lassulipes and H. nitidimenta . The aedeagus ( Fig. 49) distinctively differs from that of other members of the Jubilata group, and should be examined for reliable determinations.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.90/0.74; head 0.30/0.41; pronotum 0.44/0.52, PA 0.44, PB 0.43; elytra 1.16/0.74. Dorsum dark brown to piceous, anterior margin of pronotum slightly lighter, legs and maxillary palpi brown.

Frons punctures ca. 1xef; interstices shining, 1–4xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum finely sparsely punctate. Genae raised, shining, without posterior ridge. Pronotum cordiform, anterior margin very slightly emarginate; anterior angles sharply rounded; lateral margin between anterior angle and widest point slightly emarginate; punctures on disc ca. 1xpd those of frons, interstices strongly shining, 2–4xpd, punctures larger, deeper and denser at anterior and posterior; PF1 united to form shallow transverse impression across anterior 1/3 of pronotal disc; PF2 very shallow, oval, oblique, separated by ca. fovea width; PF3 deep; PF4 absent.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins narrow; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1.2/1/3.6/1.6. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward apex, apex joined to mesoventral midlongitudinal ridge. Plaques moderately wide, converging slightly anteriorly, weakly raised, located at sides of deep, median depression. Metaventrite with midlongitudinal ridge between mesoventral intercoxal process and median depression. AIS width at straight posterior margin slightly less than 2x P2. All legs long and very slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia straight, very slightly widened on medial margin in distal 1/4. Mesotibia very slightly arcuate. Metatibia moderately arcuate in distal 2/3. Abdominal apex symmetrical; last tergite (male) deeply notched.

Aedeagus ( Fig. 49) main piece, in ventral aspect, distinctively sinuate, with both right and left sides thickwalled, left side characteristically longer than right; both parameres, in lateral aspect, lobe-shaped distally; left paramere much longer than right; right paramere lobe-shaped in distal 1/2, setae along lower ventral margin, none at apical angle.

Etymology. "Lying on the back"; named in reference to the curvature of the aedeagus.

Distribution. Currently known from the eastern half of Area 1; elevation range 1400–2000 m ( Fig. 453 ).

Figures

FIGURE 46. Hydraena lassulipes, holotype, dorsal and lateral habitus, and venter.

FIGURE 47. Hydraena supina, holotype, dorsal and lateral habitus, and venter.

FIGURES 451–454. Geographical distributions of Hydraena species.