Hydraena limbobesa, 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 : 89-90

Hydraena limbobesa , new species

( Figs. 151 , 153, 498 )

Type Material. Holotype (male): Gulf Province: Marawaka , near Ande, elev. 1000 m, 7° 3.598' S, 145° 44.375' E, 10 xi 2006, Balke & Kinibel ( PNG 89) ( ZSM) . Paratype: Same data as holotype (1 male ZSM) .

Differential Diagnosis. Similar to H. austrobesa in body proportions and the coarse and dense dorsal punctation ( Figs. 150 , 151 ); differing therefrom by the pronotal sides not emarginate between the anterior angle and the widest part, the less evident microreticulation of the head and pronotum, and the slightly smaller size (ca. 1.36 mm vs. 1.43). The metaventral plaques are quite similar in the two species. The male genitalia of the two species differ distinctively; reliable determinations will require dissections ( Figs. 152, 153).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.36/0.59; head 0.20/0.35; pronotum 0.35/0.48, PA 0.37, PB 0.41; elytra 0.84/0.59. Dorsum dark brown to piceous; legs brown; maxillary palpi light brown to testaceous, tip not darker.

Frons punctures ca. 1xef, slightly larger and denser near eyes than medially; interstices microreticulate, dull, narrow walls to 1xpd. Clypeus microreticulate laterally, finely, sparsely punctate medially. Mentum shining, sparsely finely punctulate, each puncture with conspicuous seta; postmentum microreticulate medially, punctate and shining anteriorly and laterally. Genae raised, shining, without posterior ridge. Pronotum moderately transverse (PL/PW ca. 0.73), ca. median 3/5 of anterior margin slightly emarginate; coarsely, densely punctate, punctures on disc ca. 3xpd frons punctures, interstices on disc shining, 1–2xpd, interstices microreticulate and dull in impressions, punctures denser at anterior and posterior; PF1 shallow, obsolete; PF2 shallow; PF3 deep; PF4 shallow.

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, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, weakly shining, on disc ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect weakly separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/6/4. P1 laminate; median carina sinuate in profile. P2 narrow, raised slightly, l/w ca. 3/1, sides slightly diverging toward apex. Rim of mesocoxal cavity produced as very short carina on metaventrite. Plaques very narrow, weakly raised, converging slightly anteriorly, at sides of median depression that does not continue to P2. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 2xP2. All legs rather short, femora moderately robust. Profemur (male) without tubercle next to trochanter; protibia very slightly arcuate, widest at about distal 1/3. Mesotibia straight, lateral margin slightly arcuate and bearing contiguous row of short stout spines. Metatibia straight, very slightly widened, widest at about distal 1/ 3. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus as illustrated ( Fig. 153).

Etymology. Named in reference to being found at the border of Area 1 and Area 13, and placement in the Spinobesa group.

Distribution. Currently known only from the type locality, Marawaka near Ande, at an elevation of 1000 m ( Fig. 498 ). This is in the eastern extreme of Area 1, but also on the border with Area 13; based on the elevation (<1200 m) this species could be placed in either Area. As usual, more collecting is needed.

Figures

FIGURE 150. Hydraena austrobesa, holotype, dorsal and lateral habitus, and venter.

FIGURE 151. Hydraena limbobesa, holotype, dorsal and lateral habitus, and venter.

FIGURES 495–498. Geographical distributions of Hydraena species.