Hydraena akameku, 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 : 76-77

Hydraena akameku , new species

( Figs. 126 , 128, 403 , 489 )

Type Material. Holotype (male): Madang Province: Akameku–Brahmin , Bismarck Range, 750 m, 5° 49.307' S, 145° 24.389' E, 25 xi 2006, Balke & Kinibel ( PNG 114) ( ZSM) . Paratypes: Same data as holotype (17 MCZ, NHM, NMW, PNG, ZSM) .

Differential Diagnosis. Recognized by the narrow body form, the coarsely densely punctate dorsum, and the very narrow mesoventral intercoxal process (P2). Neither the dorsal habitus nor the male genitalia show a close affinity with other species groups ( Figs. 126 , 128).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.39/0.56; head 0.23/0.33; pronotum 0.34/0.44, PA 0.36, PB 0.34; elytra 0.83/0.56.

Dorsum of head dark brown to piceous; pronotum light brown to testaceous in front of and behind piceous fascia, ratios of color bands, as measured in midline, ca. 6/13/4; elytra dark brown; legs light brown; maxillary palpi testaceous, tip very slightly darker. Dorsum weakly shining.

Frons punctures ca. 2xef near eyes, smaller and sparser medially; interstices shining, 1–3xpd. 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, weakly shining, without posterior ridge. Pronotum cordiform, median 2/3 of anterior margin emarginate; sides straight or 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 anteriorly and posteriorly denser than those on disc; PF1 and PF4 very shallow; PF2 moderately deep, medially conjointly shallowly confluent; PF3 moderately deep, wide.

Elytra widest at about midlength; summit of posterior declivity at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, very weakly 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. 1/2.5/5/2. P1 laminate; median carina sinuate in profile, slightly raised between coxae. P2 very narrow, length/width ca. 6/1, sides very slightly converging toward blunt apex. Plaques large, slightly raised, at sides of narrow median depression, anteriorly slightly tapering and slightly convergent. Metaventrite flat between mesocoxae. AIS width at straight posterior margin ca. 4x P2. All legs of moderate length. Profemur (male) with minute tubercle on ventral margin near trochanter; protibia very slightly arcuate, increasing in width from base to apex. Mesotibia straight. Metatibia straight, very slightly increasing in width in distal 1/2. Abdominal apex symmetrical; last tergite (male) with large, deep apicomedian notch.

Etymology. Named in reference to the type locality.

Distribution. Currently known only from the type locality in the Bismarck Range, in the eastern part of Area 2; elevation 750 m ( Fig. 489 ).

Figures

FIGURE 126. Hydraena akameku, holotype, dorsal and lateral habitus, and venter.

FIGURES 400–403. Female tergite X, gonocoxite, and spermatheca of Hydraena species.

FIGURES 487–490. Geographical distributions of Hydraena species.