Hydraena inhalista, 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 : 107-108

Hydraena inhalista , new species

( Figs. 187 , 189 , 519 )

Type Material. Holotype (male): Madang Province: Finisterre Mts., Naho River Valley, Damanti , ex gravel bank of shallow stream, 1082 m, 5° 55' S, 145° 58' E, 12 x 1964, M. E. Bacchus (MEB 49) ( NHM) . Paratypes (23): 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 (1 NMW) ; Madang Province: Same data as holotype (2 NHM) ; Finisterre Mts., Naho River Valley, Damanti , ex small pool, probably permanent, in clay in dense shade, 1067 m, 5° 55' S, 145° 58' E, 8 x 1964, M. E. Bacchus (MEB 39) (10 NHM) ; Morobe Province: Wau, Wau Ecology Institute , secondary montane rainforest, pan trap, 1200 m, 7° 20' S, 146° 43' E, 1–30 viii 1983, S. & P. Miller (10 BPBM) .

Differential Diagnosis. Similar in size (ca. 1.37–1.39 mm), body proportions and color to H. exhalista ( Figs. 187 , 190 ). These two species have the anterior and posterior widths of the pronotum equal; in the other species in the Impala group the pronotum is slightly narrower anteriorly than at the base. Hydraena inhalista differs from H. exhalista in the slightly narrower body form (EW/TL ca. 0.43 vs. 0.45), the slightly coarser punctation on the frons disc, the non-concave mesoventral intercoxal process (P2), and the slightly different plaque ratios (ca. 4/1/4/6 vs. 5/ 1/5/5). In addition, the male protibiae differ slightly in the two species. 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. 189 , 192 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.37/0.59; head 0.21/0.33; pronotum 0.34/0.46, PA 0.36, PB 0.36; elytra 0.79/0.59.

Dorsum of head with frons dark brown to reddish brown, clypeus slightly lighter, labrum testaceous; pronotum brown around ill-defined dark brown macula on disc; elytra dark brown to reddish brown; legs brown to light reddish brown; maxillary palpi testaceous, tip not darker.

Frons punctures ca. 1–2xef, slightly larger near eyes than medially; interstices shining, 1–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum micropunctulate, dull. 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 slightly larger and denser at anterior and posterior; PF1 very shallow, obsolete; PF2 very shallow, obsolete; PF3 moderately deep; PF4 very shallow.

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, a few punctures subserial, punctures becoming gradually smaller toward posterior. 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.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 4/1/4/6. P1 ca. 1/2 P2; median carina bisinuate in profile. P2 l/w ca. equal, sides slightly diverging toward non-concave, blunt apex. Plaques short, very narrow, carinate, parallel, at sides of deep median depression. Metaventrite concave between P2 and plaques. AIS conjointly concave with anterior area of first ventrite, width at straight posterior margin ca. 1.5x P2. All legs moderately long and slen- der. Profemur (male) with tubercle next to trochanter; protibia very slightly arcuate, anterior margin very slightly widened subapically. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 189 ).

Etymology. "Inhaler"; named in reference to the concavity between the metaventral plaques and on the first abdominal sternite, and to the expanded area between the mesocoxae.

Distribution. Currently known from one locality in eastern Area 1 (1540 m), two very narrowly separated sites across the Markham Valley in the Finisterre Mts. of Area 5 (1067 m and 1082 m), and one locality in Area 6 (1540 m) ( Fig. 519 ).

Figures

FIGURE 187. Hydraena inhalista, holotype, dorsal and lateral habitus, and venter.

FIGURE 190. Hydraena exhalista, holotype, dorsal and lateral habitus, and venter.

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

FIGURES 519–522. Geographical distributions of Hydraena species.

FIGURES 192–193. Aedeagi of holotypes. 192. H. exhalista. 193. H. apertista.