Hydraena brahman, 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 : 82-83

Hydraena brahman , new species

( Figs. 138 , 140 , 562 )

Type Material. Holotype (male): Madang Province: Ramu Valley , 4.5 km N Brahman, [GE est.] 130–150 m, 5° 39' S, 145° 22' E, 18 iv 1991, D. Larson ( MCZ).

Differential Diagnosis. A very small species (ca. 1.16 mm) with a rectangular pronotal macula ( Fig. 138 ). This species may be confused with small members of the Manulea group, but distinctively differs therefrom in the form of the male genitalia. Hydraena brahman is a member of the Rudallensis group, which has eleven Australian species. Examination of the male genitalia will be necessary for reliable determinations ( Fig. 140 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.16/0.47; head 0.20/0.30; pronotum 0.30/0.38, PA 0.32, PB 0.35; elytra 0.67/0.47. Dorsum of head with frons dark brown to piceous, clypeus and labrum brown; pronotum testaceous around brown, very diffusely margined, rectangular macula, ratios of color bands, as measured in midline, ca. 5/10/4; elytra dark brown; legs light brown; maxillary palpi testaceous, tip not darker. Dorsum moderately shining.

Frons punctures ca. 1xef near eyes, smaller and sparser medially; interstices shining, medially 1–3xpd. Clypeus effacedly microreticulate laterally, very finely sparsely punctulate and shining medially. Mentum very sparsely very finely punctulate, strongly shining. Postmentum microreticulate in shallow median depression, otherwise finely sparsely punctulate. Genae very slightly raised, shining, without posterior ridge. Pronotum transverse, median 1/2 of anterior margin emarginate; sides slightly arcuate between anterior angle and widest part, very weakly sinuate between widest part and posterior angle; punctures on disc ca. 1xpd largest frons punctures, interstices shining, ca. 1–3xpd, punctures anteriorly and posteriorly slightly larger and denser than those on disc; PF1 and PF4 very shallow or absent; PF2 shallow, obsolete; PF3 shallow, wide.

Elytra widest at about midlength; summit of posterior declivity at or very near midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly smaller than largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior; each puncture with distinct recumbent seta that attains next serial puncture. Intervals not raised, very weakly shining, on disc ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect very slightly separately rounded, in posterior aspect margins forming moderate angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/5/4. P1 laminate; median carina very slightly sinuate in profile, slightly raised between coxae. P2 length/width ca. 5/2, sides very slightly converging toward blunt apex. Plaques carinate lines, at sides of deep median depression, anteriorly slightly convergent. Metaventrite flat between mesocoxae. AIS width at straight posterior margin ca. 2x P2. All legs of moderate length. Profemur (male) without tubercle on ventral margin; protibia slightly arcuate, gradually increasing in width from base to apex. Mesotibia straight. Metatibia very slightly arcuate, slender. Abdominal apex very slightly asymmetrical; last tergite (male) with small apical notch, slightly offset to left side. Aedeagus as illustrated ( Fig. 140 ).

Etymology. Named in reference to the type locality.

Distribution. Currently known only from the type locality near Brahman; this is in the eastern arm of Area 3, elevation 130–150 m ( Fig. 562 ). Hydraena brahman is the putative sister species of the Australian species H. ambiosina , which has distribution records around the Gulf of Carpenteria ( Fig. 561 ).

Figures

FIGURE 138. Hydraena brahmin, holotype, dorsal and lateral habitus, and venter.

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

FIGURES 559–562. Geographical distributions of Hydraena species.