Hydraena exhalista, 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 : 108-109

Hydraena exhalista , new species

( Figs. 190 , 192 , 524 )

Type Material. Holotype (male): Gulf Province: Marawaka , Mala, 1400 m, 7° 5.664' S, 145° 44.467' E, 11 xi 2006, Balke & Kinibel ( PNG 90) ( ZSM) . Paratypes: Same data as holotype (3 ZSM) .

Differential Diagnosis. Similar in size (ca. 1.37–1.39 mm), body proportions and color to H. inhalista ( Figs. 187 , 190 ). These two species have the anterior and posterior widths of the pronotum equal; in the other species in the Impala group the pronotum is slightly narrower anteriorly than at the base. Hydraena exhalista differs from H. inhalista in the slightly wider body form (EW/TL ca. 0.45 vs. 0.43), the finer punctation on the frons disc, the concave mesoventral intercoxal process (P2), and the slightly different plaque ratios (ca. 5/1/5/5 vs. 4/1/4/6). In addition, the male protibiae differ slightly in the two species, with the distal enlargement wider in H. exhalista . The general plan of the male genitalia of the two species also suggests a relationship, but the genitalia distinctively differ in details, and should be examined for reliable determinations ( Figs. 189 , 192 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.39/0.63; head 0.24/0.34; pronotum 0.34/0.47, PA 0.38, PB 0.38; elytra 0.83/0.64. Dorsum of head with frons dark reddish brown, clypeus lighter, brown, labrum testaceous; pronotum brown to light reddish brown; elytra dark brown to dark reddish brown; legs reddish brown; maxillary palpi testaceous, tip not darker.

Frons punctures ca. 1–2xef, much larger and denser near eyes than medially; interstices shining, on disc ca. 1– 4xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum effacedly microreticulate. Genae raised, shining, without posterior ridge. Pronotum subcordiform, ca. median 3/4 of anterior margin arcuate to posterior; punctures on disc ca. 0.5xpd frons punctures, interstices shining, 2–4xpd, punctures larger and denser at anterior and posterior; PF1 very shallow, obsolete; PF2 moderately deep; PF3 deep; PF4 absent or very shallow.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins rather wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–3xpd, 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. 5/1/5/5. P1 ca. 2/5 P2; median carina bisinuate in profile. P2 transversely slightly concave, l/w ca. equal, sides slightly diverging toward blunt apex. Plaques very narrow, carinate, parallel or converging very slightly anteriorly, at sides of deep median depression. Metaventrite concave between P2 and plaques. AIS width at straight posterior margin very slightly greater than P2. All legs moderately long and slender. Profemur (male) with small tubercle next to trochanter; protibia slightly arcuate, distal 1/3 markedly widened on anterior margin, medial margin flat except small sharp tubercle subapically on posteromedial margin. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) very deeply notched. Aedeagus as illustrated ( Fig. 192 ).

Etymology. Named in reference to relationship with H. inhalista , and the less concave mesoventrite.

Distribution. Currently known only from the type locality, Marawaka, Mala, in the extreme southeastern part of Area 1, at the border with Area 13; elevation 1400 m ( Fig. 524 ).

Figures

FIGURE 187. Hydraena inhalista, holotype, dorsal and lateral habitus, and venter.

FIGURE 190. Hydraena exhalista, holotype, dorsal and lateral habitus, and venter.

FIGURES 192–193. Aedeagi of holotypes. 192. H. exhalista. 193. H. apertista.

FIGURES 523–526. Geographical distributions of Hydraena species.

FIGURES 188–189. Aedeagi of holotypes. 188. H. galea. 189. H. inhalista.