Hydraena quadriplumipes, 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 : 77-78

Hydraena quadriplumipes , new species

( Figs. 127 , 129, 490 )

Type Material. Holotype (male): Madang Province: Aiome area , 130 m, 5° 10.593' S, 144° 42.8' E, 11 iii 2007, Kinibel ( PNG 156) ( ZSM).

Differential Diagnosis. Somewhat similar in dorsal habitus and color to H. marawaka (Otiarca group) and H. foliobba (Foliobba group) ( Figs. 50 , 62 , 127 ); differing from members of both groups by the modifications of the male legs and the form of the aedeagus. The setal brushes on the male meso- and metatibiae, and the markedly arcuate mesotibiae suggest relationship to H. mercuriala (Mercuriala group), and the aedeagus of H. quadriplumipes could represent a less derived condition for that group ( Figs. 129, 132). Dorsally, H. quadriplumipes is immediately differentiated from H. mercuriala and H. ollopa ( Figs. 127 , 130 , 131 ) by the distinctive pronotal fascia.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.73/0.68; head 0.29/0.41; pronotum 0.42/0.52, PA 0.45, PB 0.42; elytra 1.05/0.68. Dorsum of head piceous; pronotum testaceous in front of and behind dark brown to piceous fascia, ratios of color bands, as measured in midline, ca. 8/11/3; elytra dark brown; legs light brown; maxillary palpi testaceous, tip of palpus not darker.

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

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–2xpd, as are interstices between punctures of a row, a few punctures subserial. 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. 3.5/1/7/4. P1 laminate; median carina sinuate in profile. P2 weakly raised, l/w as ca. 5/3.5, sides slightly converging toward blunt apex. Plaques carinate lines, height gradually increasing from anterior to posterior, parallel, located at sides of deep, median depression. Metaventrite without midlongitudinal ridge. AIS width at arcuate posterior margin ca. 1.7x P2. All legs moderately long and slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia very slightly arcuate, gradually increasing in width from base to apex, distal 1/5 of medial margin with row of closely spaced, very short spines. Mesotibia markedly arcuate, distal 1/3 markedly widened; mesotarsus with brush of setae on basal tarsomeres. Metatibia very weakly arcuate, distal 1/2 of medial margin with hair-like setae that lie flat on cuticle in dry specimens; metatarsus with small brush of setae on basal tarsomeres. Abdominal apex symmetrical; last tergite (male) notched.

Etymology. Named in reference to the meso- and metatarsal setal brushes.

Distribution. Currently known only from the type locality, the Aiome area, in central Area 2; elevation 130 m ( Fig. 490 ). Perhaps to be expected also in Area 3, based on the elevation.

Figures

FIGURE 50. Hydraena foliobba, holotype, dorsal and lateral habitus, and venter.

FIGURE 62. Hydraena marawaka, holotype, dorsal and lateral habitus, and venter.

FIGURE 127. Hydraena quadriplumipes, holotype, dorsal and lateral habitus, and venter.

FIGURE 130. Hydraena mercuriala, holotype, dorsal and lateral habitus, and venter.

FIGURE 131. Hydraena ollopa, holotype, dorsal and lateral habitus, and venter.

FIGURES 487–490. Geographical distributions of Hydraena species.