Hydraena galea, 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 : 106-107

Hydraena galea , new species

( Figs. 186 , 188 , 523 )

Type Material. Holotype (male): Eastern Highlands Province: Akameku-Brahmin , Bismarck Range, 700 m, 5° 52.754' S, 145° 23.209' E, 24 xi 2006, Balke & Kinibel ( PNG 109) ( ZSM) . Paratypes (2): Eastern Highlands Province: Sepik River Basin , stream beside milestone labelled G-99, unshaded stream with angular boulders, some coated with java moss, 1540 m, 6° 18' S, 145° 55' E, 1 vii-30 viii 1988, D. Dudgeon (2 NMW) .

Differential Diagnosis. Similar in color and dorsal sculpture to H. impala ( Figs. 183 , 186 ); differing therefrom by the slightly wider body form (EW/TL ca. 0.45 vs. 0.40), the wider mesoventral intercoxal process (P2) (plaque ratios ca. 5/1/5/5 vs. 4/1/5/5), and the non-micropunctulate mentum. The general plan of the male genitalia of the two species also suggests a relationship, but the genitalia distinctively differ in details, and should be examined for reliable determinations ( Figs. 185 , 188 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.45/0.65; head 0.19/0.34; pronotum 0.35/0.49, PA 0.35, PB 0.38; elytra 0.92/0.65. Dorsum of head with frons dark brown to dark reddish brown, clypeus lighter, brown, labrum testaceous; pronotum brown around ill-defined dark reddish brown macula on disc; elytra dark brown to dark reddish brown; legs reddish brown; maxillary palpi testaceous, tip not darker.

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

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins rather wide in anterior 1/2; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 2–3xpd, as are interstices between punctures of a row. 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. 5/1/5/5. P1 ca. 2/5 P2; median carina bisinuate in profile. P2 l/w ca. 4/5, sides slightly diverging toward blunt apex. Plaques very narrow, carinate, converging slightly anteriorly, at sides of deep median depression. Metaventrite concave between P2 and plaques. AIS width at straight posterior margin ca. 1.4x P2. All legs moderately long and slender. Profemur (male) with small tubercle next to trochanter; protibia slightly arcuate, anterior margin very slightly widened subapically, medial margin flat except small sharp tubercle subapically on posteromedial margin. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 188 ).

Etymology. Named in reference to the helmet shape of the distal piece of the aedeagus.

Distribution. Currently known from two localities at the border of the eastern parts of Areas 1 and 2, at very different elevations of 700 m and 1540 m ( Figs. 523 ).

Figures

FIGURE 183. Hydraena impala, holotype, dorsal and lateral habitus, and venter.

FIGURE 186. Hydraena galea, holotype, dorsal and lateral habitus, and venter.

FIGURES 188–189. Aedeagi of holotypes. 188. H. galea. 189. H. inhalista.

FIGURES 523–526. Geographical distributions of Hydraena species.

FIGURES 184–185. Aedeagi of holotypes. 184. H. buloba. 185. H. impala.