Hydraena adelbertensis, 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 : 69

Hydraena adelbertensis , new species

( Figs. 110 , 112, 486 )

Type Material. Holotype (male): Madang Province: Adelbert Mts. , below Keki, 790 m, 4° 42.3' S, 145° 25.089' E, 5 v 2006, Balke & Manaono ( PNG 53) ( ZSM) . Paratypes (3): Madang Province: Same data as holotype (1 ZSM); Keki, Adelbert Mts., 400 m, 4° 43.058' S, 145° 24.437' E, 29 xi 2006, Binatang Boys ( PNG 119) (2 ZSM) .

Differential Diagnosis. Among members of the Velvetina group, somewhat similar in habitus to H. ibalimi , H. incista and H. copulata ( Figs. 107 , 110 , 114 ); in addition to habitus similarities, all four species have the frons slightly concave. Hydraena adelbertensis differs from the compared species by the smaller size (ca. 1.52 vs. 1.60– 1.78 mm); in addition, it differs from H. incista by the more transverse pronotum, and from H. copulata by the proportionally shorter elytra. Hydraena adelbertensis and H. ibalimi are the only species of the Velvetina group with metaventral plaques (they are tiny). Hydraena adelbertensis is differentiated from H. ibalimi by the hairy dorsum, the proportionally smaller elytra, and the differently shaped male metatibiae. The aedeagi of the two species also indicate a relationship, while differing distinctively in detailed structure ( Figs. 109 , 112).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.52/0.62; head 0.25/0.35; pronotum 0.39/0.44, PA 0.37, PB 0.32; elytra 0.87/0.62. Dorsum piceous, except light brown to testaceous band across anterior 1/4 of pronotum; legs brown to reddish brown; maxillary palpi light brown to testaceous, tip slightly darker.

Frons slightly concave near eyes, punctures ca. 1xef; interstices shining, 1–2xpd. Clypeus microreticulate laterally, sparsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum cordiform, anterior margin straight or very slightly arcuate; punctures on disc ca. 1–2xpd those of frons, each puncture with short but distinctive seta; interstices shining, 1– 3xpd, punctures slightly larger and much denser at anterior and posterior; PF1 very shallow; PF2 deep, large, oval, oblique, very shallowly confluent; PF3 deep; PF4 moderately deep.

Elytra convex, 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, some punctures subserial near base; each puncture with distinctive, short seta. Intervals not raised, 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.

P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward apex. Plaques extremely small, carinate, located on sides of deep median depression, hydrofuge pubescence longest lateral to median depression. AIS width at straight posterior margin ca. 2x P2. All legs long and slender. Profemur (male) without tubercle next to trochanter; protibia straight, medial margin gradually widening from base to slightly past midlength, then emarginate to apex, widest point with a few large spines, emargination with row of very short spines. Mesotibia straight. Metatibia straight, medial margin slightly emarginate. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus as illustrated ( Fig. 112).

Etymology. Named in reference to the geographical distribution, the Adelbert Mountains.

Distribution. Currently known from two very narrowly separated localities in the Adelbert Mts., in Area 5; elevations 400 m and 790 m ( Fig. 486 ).

Figures

FIGURE 107. Hydraena ibalimi, holotype, dorsal and lateral habitus, and venter.

FIGURE 110. Hydraena adelbertensis, holotype, dorsal and lateral habitus, and venter.

FIGURE 114. Hydraena incista, holotype, dorsal and lateral habitus, and venter.

FIGURES 483–486. Geographical distributions of Hydraena species.

FIGURES 108–109. Aedeagi of holotypes. 108. H. velvetina. 109. H. ibalimi.