Hydraena ramuquintana, 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 : 125-126

Hydraena ramuquintana , new species

( Figs. 230 , 232 , 558 )

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) . Paratypes: Same data as holotype (2 MCZ) .

Differential Diagnosis. Similar to H. quintana in dorsal habitus, small size (ca. 1.21 mm), and subserial to random discal elytral punctures ( Figs. 227 , 230 ); differing therefrom ventrally in plaque ratios, H. ramuquintana having the plaques less convergent anteriorly and P2 wider (ratios ca. 3/1.5/5/4 vs. 2/2/73). Males of the two species are immediately differentiated by the highly modified abdominal ventrites of H. quintana (SEM Figs. 356, 357 , 361 ). The male genitalia of all three species in the Quintana group distinctively differ from one another in the shapes of the processes of the distal piece ( Figs. 229, 232, 233 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.21/0.50; head 0.22/0.30; pronotum 0.33/0.41, PA 0.32, PB 0.37; elytra 0.71/0.50. Dorsum of head dark brown to piceous, lateral areas of clypeus slightly lighter; pronotum testaceous in front of and behind brown to dark brown, diffusely margined, fascia, ratios of color bands, as measured in midline, ca. 5/11/5; elytra brown; legs light brown; maxillary palpi testaceous, tip not darker. Dorsum shining.

Frons punctures ca. 1xef near eyes, smaller and sparser medially; interstices shining, 1–5xpd. Clypeus effacedly microreticulate laterally, very finely sparsely punctulate and shining medially. Mentum effacedly microreticulate, very sparsely very finely punctulate, weakly shining. Postmentum microreticulate in shallow median depression, otherwise finely sparsely punctate. Genae very slightly raised, shining, with shallow, obsolete median impression, without posterior ridge. Pronotum transverse, ca. median 3/4 of anterior margin slightly arcuate to posterior, sides weakly arcuate, slightly emarginate between midlength and posterior angle; punctures on disc very fine and very sparse, slightly smaller than largest frons punctures, interstices shining, ca. 6–8xpd, punctures anteriorly and posteriorly slightly larger than those on disc; PF1 and PF4 absent; PF2 very shallow, completely shallowly confluent in midline to form U-shaped impression; PF3 moderately deep, wide.

Elytra widest at about midlength; summit of posterior declivity at or very near midlength; lateral explanate margins narrow; on basal 1/3 punctures subserial to random, ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–3xpd. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming moderately deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 3/1.5/5/4. P1 laminate; median carina sinuate in profile, slightly raised behind coxae. P2 length/width ca. 5/3, sides very slightly diverging toward blunt, raised apex. Plaques slightly rounded, at sides of median depression, anteriorly tapering and slightly convergent. Metaventrite between mesocoxae very weakly raised in midline. AIS width at straight posterior margin slightly wider than P2. All legs of moderate length. Profemur (male) without tubercle on ventral margin; protibia straight, very slightly widened on medial margin at about midlength. Meso- and metatibia straight, slender. Abdominal apex very slightly asymmetrical; last tergite (male) with very small apicomedian notch. Aedeagus as illustrated ( Fig. 232 ).

Etymology. Named in reference to the geographical distribution and relationship to H. quintana .

Distribution. Currently known only from the type locality near Brahman in the Ramu Valley; this is in the eastern arm of Area 3; elevation 130–150 m ( Fig. 558 ).

Figures

FIGURE 227. Hydraena quintana, holotype, dorsal and lateral habitus, and venter.

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

FIGURES 232–233. Aedeagi of holotypes. 232. H. ramuquintana. 233. H. buquintana.

FIGURES 555–558. Geographical distributions of Hydraena species.

FIGURES 352–357. Scanning electron micrographs of H. quintana.

FIGURES 358–363. Scanning electron micrographs of H. quintana (358–361) and H. otiarca (362–363).