Hydraena sepikramuensis, 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 : 29

Hydraena sepikramuensis , new species

( Figs. 26 , 28 , 448 )

Type Material. Holotype (male): Madang Province: Ramu Valley, Sare River , 4 km N Brahman, [GE est.] 130– 150 m, 5° 39' S, 145° 22' E, 16 iv 1991, D. Larson ( MCZ) . Paratypes (29): Madang Province: Aiome area , 130 m, 5° 10.593' S, 144° 42.8' E, 11 iii 2007, Kinibel ( PNG 156) (22 MCZ, NHM, NMW, PNG, ZSM) ; Ramu Valley , Mum River at Brahman, [GE est.] 130–150 m, 5° 42' S, 145° 22' E, 16 iv 1991, D. Larson (1 MCZ) ; Sepik-Ramu Basin , Mom Creek, substrate of smooth cobbles set in coarse sand, loosely packed, 20% shaded, water shallow, 170 m, 5° 45' S, 145° 20' E, 1 vi–30 vii 1988, D. Dudgeon (1 NMW) ; Sandaun Province: Bewani Stn. , forest puddles at base of Bewani Mts., 300 m, 3° 5.13' S, 141° 10.227' E, 12 iv 2006, Balke & Sagata ( PNG 38) (5 ZSM) .

Differential Diagnosis. Among members of the Manulea group, similar in body shape to H. thumbelina ( Figs. 26 , 27 ); differing therefrom by the smaller size (ca. 1.33 vs. 1.40 mm), the narrower pronotal fascia (color bands ca. 6/10/5 vs. 4/15/4), the subserial to random discal elytral punctures, and the differently shaped metaventral plaques. The male genitalia of the two species distinctively differ ( Figs. 28, 29 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.55; head 0.23/0.32; pronotum 0.32/0.40, PA 0.35, PB 0.34; elytra 0.81/0.55. Dorsum of head piceous; pronotum testaceous in front of and behind piceous fascia, ratios of color bands, as measured in midline, ca. 6/10/5; elytra brown; legs light brown to testaceous; maxillary palpi testaceous, tip of palpus slightly darker.

Frons punctures ca. 1xef, slightly larger near eyes than medially; interstices shining, 1–4xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum cordiform, median 1/2 of anterior margin very slightly emarginate; punctures on disc ca. 1–2xpd those of frons, interstices shining, 1–3xpd, punctures slightly larger and denser at anterior and posterior; PF1 absent; PF2 very shallow, obsolete; PF3 deep; PF4 absent.

Elytra with summit of posterior declivity slightly past midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior; many punctures on disc subserial or random. Intervals not raised, shining, on disc ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect separately rounded, in posterior aspect margins forming moderately deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 3/2/6/2. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides converging toward blunt apex. Plaques moderately wide, converging very slightly anteriorly, weakly raised, located at sides of deep, median depression, each plaque tapering slightly from posterior to anterior. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin slightly wider than P2. All legs moderately long and slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia arcuate, distal 1/3 slightly widened on anterior surface and on medial margin, medial margin apically with cluster of very short spines. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus as illustrated ( Fig. 28 ).

Etymology. Named in reference to the geographical distribution.

Distribution. A lowland species, currently known from the Sepik-Ramu basin, Area 3, but very near the bor- der of Areas 4 in the west and Area 2 in the east; elevation range 130–300 m ( Fig. 442 ).

Figures

FIGURE 26. Hydraena sepikramuensis, holotype, dorsal and lateral habitus, and venter.

FIGURE 27. Hydraena thumbelina, holotype, dorsal and lateral habitus, and venter.

FIGURES 28–29. Aedeagi of holotypes. 28. H. sepikramuensis. 29. H. thumbelina.

FIGURES 447–450. Geographical distributions of Hydraena species.

FIGURES 439–442. Geographical distributions of Hydraena species.