Hydraena einsteini, 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 : 83-84

Hydraena einsteini , new species

( Figs. 139 , 141 , 470 )

Type Material. Holotype (male): Central Province: Port Moresby – Brown River road, ex small pool in dry gravelly stream bed, [GE est.] 50–100 m, 9° 24' S, 147° 14' E, 15 iii 1965, M. E. Bacchus (MEB 196) ( NHM) . Paratypes: Same data as holotype (10 NHM) .

Differential Diagnosis. Somewhat similar in dorsal habitus to H. spinobesa and H. reticulobesa ( Figs. 139 , 142 , 143 ); differentiated from those members of the Spinobesa group by the non-microreticulate interstices of the head and pronotum, the generally more prominent setae of the dorsum, the presence of a pronotal macula, and the carinate metaventral plaques. The male genitalia of the three species are abundantly distinct ( Figs. 141 , 144, 145 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.20/0.49; head 0.19/0.28; pronotum 0.30/0.39, PA 0.31, PB 0.31; elytra 0.71/0.49. Dorsum of head dark brown; pronotum light brown around brown, very diffusely margined, faint rectangular macula, ratios of color bands, as measured in midline, ca. 5/10/5; elytra dark brown; legs brown; maxillary palpi testaceous, tip not darker. Dorsum very weakly shining.

Frons punctures rather coarse, ca. 2xef near eyes, smaller and slightly sparser medially; interstices shining, 1– 2xpd. Clypeus effacedly microreticulate laterally, very finely sparsely punctulate and shining medially. Mentum very sparsely very finely punctulate, strongly shining. Postmentum effacedly microreticulate in posterior 1/2, otherwise finely sparsely punctulate. Genae very slightly raised, shining, with very small, shallow, obsolete median impression, without posterior ridge. Pronotum weakly cordiform, median 1/2 of anterior margin emarginate; sides very slightly emarginate between anterior angle and widest part, sinuate between widest part and posterior angle; punctures on disc ca. 1xpd largest frons punctures, interstices shining, ca. 1–2xpd, punctures posteriorly slightly larger and denser than those on disc; PF1 and PF4 very shallow or absent; PF2 shallow, obsolete; PF3 wide, shallow.

Elytra transversely convex, widest at about midlength; summit of posterior declivity slightly anterior to midlength; lateral explanate margins moderately wide; punctures coarse, on basal 1/3 punctures ca. 2xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, very weakly shining, on disc ca. 0.5–1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rather sharply rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/5/4. P1 laminate; median carina sinuate in profile, slightly raised between coxae. P2 length/width ca. 5/2, sides parallel, apex blunt. Plaques carinate lines, gradually increasing in height from anterior to posterior, at sides of median depression, anteriorly very slightly convergent. Metaventrite flat between mesocoxae. AIS width at straight posterior margin ca. 1.5x P2; slightly narrower than separation of plaques. All legs of moderate length, femora rather stout. Profemur (male) without tubercle on ventral margin; protibia very slightly arcuate, rather stout, gradually increasing in width from base to subapically, then narrowed. Mesotibia straight. Metatibia very slightly, if at all, arcuate, slender. Abdominal apex symmetrical; last tergite (male) with very small apicomedian notch.

Etymology. Dedicated to the famous physicist.

Distribution. Currently known only from the type locality near Port Moresby, Area 11; elevation estimated at 50–100 m ( Fig. 470 ).

Figures

FIGURE 139. Hydraena einsteini, holotype, dorsal and lateral habitus, and venter.

FIGURE 142. Hydraena spinobesa, holotype, dorsal and lateral habitus, and venter.

FIGURE 143. Hydraena reticulobesa, holotype, dorsal and lateral habitus, and venter.

FIGURES 140–141. Aedeagi of holotypes. 140. H. brahmin. 141. H. einsteini.

FIGURES 467–470. Geographical distributions of Hydraena species.

FIGURES 144–145. Aedeagi of holotypes. 144. H. spinobesa. 145. H. reticulobesa.