Hydraena ramuensis, 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 : 65-66

Hydraena ramuensis , new species

( Figs. 102 , 104, 477 )

Type Material. Holotype (male): Madang Province: Ramu Valley , 6 km N Brahman, [GE est.] 130–150 m, 5° 38' S, 145° 22' E, 21 vi 1991, D. Larson ( MCZ).

Differential Diagnosis. Similar to H. clarinis (Colorata group) in having a completely testaceous pronotum ( Figs. 99 , 230 ); differentiated therefrom by the larger size (ca. 1.22 vs. 1.13 mm), the much more convex and ovate elytra that have a testaceous macula, and the more coarsely punctate dorsum. The male genitalia of the two species distinctively differ ( Figs. 101 , 104).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.22/0.54; head 0.16/0.30; pronotum 0.30/0.38, PA 0.30, PB 0.33; elytra 0.76/0.54. Dorsum of head dark brown to piceous; pronotum testaceous; elytra dark brown with light brown to testaceous macula across middle area, and similarly colored elytral apices; legs light brown to testaceous; maxillary palpi testaceous, tip not darker. Dorsum weakly shining.

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

Elytra ovoid, transversely very convex, widest at about midlength; summit of posterior declivity distinctly anterior to midlength, at ca. anterior margin of macula; 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 very slightly separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/5/4. P1 laminate; median carina sinuate in profile, slightly raised between coxae. P2 length/width ca. 5/2, sides very slightly converging toward blunt, slightly raised apex. Plaques very narrow but not carinate, at sides of median depression, anteriorly tapering, parallel or very slightly convergent. Metaventrite transversely slightly concave between mesocoxae, tip raised to join with tip of P2. AIS width at straight posterior margin ca. 2x P2. All legs of moderate length. Profemur (male) with tubercle on ventral margin near trochanter; protibia slightly arcuate, slightly widened in distal 1/2. Meso- and metatibia straight, slender. Metatrochanter with minute tubercle. Abdominal symmetrical; last tergite (male) with deep apicomedian notch. Aedeagus as illustrated ( Fig. 104).

Etymology. Named in reference to the Ramu Valley.

Distribution. Currently known only from the type locality in eastern Area 3; elevation 130–300 m ( Fig. 477 ).

Figures

FIGURE 99. Hydraena clarinis, holotype, dorsal and lateral habitus, and venter.

FIGURE 102. Hydraena ramuensis, holotype, dorsal and lateral habitus, and venter.

FIGURE 230. Hydraena ramuquintana, holotype, dorsal and lateral habitus, and venter.

FIGURES 475–478. Geographical distributions of Hydraena species.

FIGURES 100–101. Aedeagi of holotypes. 100. H. nanocolorata. 101. H. clarinis.