Hydraena pala, 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 : 113-114

Hydraena pala , new species

( Figs. 202 , 204 , 411 , 527 )

Type Material. Holotype (male): Morobe Province: Lae–Bulolo road, Gurakor Creek , ex gravel banks, [GE est.] 900–1100 m, 6° 50' S, 146° 37' E, 30 xii 1964, M. E. Bacchus (MEB 133) ( NHM) . Paratypes (14): Madang Province: Sepik Ramu Basin, Kojé Creek , unshaded creek, small to medium cobbles, gravel and fine sand (the latter in areas of slack water), filamentous algae on stony substrates, small accumulations of leaf litter, 160 m, 5° 33' S, 145° 23' E, 1 vii–30 viii 1988, D. Dudgeon (10 NMW) ; Morobe Province: Same data as holotype (3 NHM) ; Western Highlands Province: Bayer / Rokina, Antenge River , [GE est.] 1100–1300 m, 5° 32' S, 144° 18' E, 1 v 1979, W. G. Ullrich (1 MHNG) .

Differential Diagnosis. Very similar in color, body form and dorsal sculpture to H. palamita ( Figs. 202 , 207 ); differing therefrom in slightly larger size (ca. 1.58 vs. 1.47 mm) and the slightly more widely separated plaques (ratios ca. 6/1/6/6 vs. 6/1/6/5). The male genitalia show a similarity in basic plan, but differ distinctively in several details, most notably the shape of the left paramere ( Figs. 204 , 209); reliable determinations will require examination of the aedeagi.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.58/0.66; head 0.25/0.36; pronotum 0.38/0.49, PA 0.37, PB 0.40; elytra 0.97/0.66. Dorsum of head dark brown to reddish brown; pronotum light brown to testaceous; elytra dark brown to reddish brown, with very faint slightly more lightly colored macula at posterior declivity; legs brown to light reddish brown; maxillary palpi testaceous, tip not darker.

Frons punctures ca. 1xef, slightly larger near eyes than medially; interstices shining, 1–4xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum micropunctulate. Genae raised, shining, without posterior ridge. Pronotum subcordiform, ca. median 3/4 of anterior margin emarginate; 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; 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. 6/1/6/6. P1 ca. 1/2 P2; median carina straight in profile; postcoxal process medially concave. P2 transversely concave, length slightly less than width, sides slightly diverging toward blunt apex. Plaques very narrow, carinate, converging slightly anteriorly, at sides of very deep median depression. Metaventrite concave between P2 and plaques. AIS width at straight posterior margin ca. 1.5x P2. All legs moderately long and slender. Profemur (male) with very small tubercle next to trochanter; protibia slightly arcuate, distal 1/3 widened anteriorly, medial margin flat except small sharp tubercle subapically on posteromedial margin. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) deeply notched, each side of notch produced in point. Aedeagus as illustrated ( Fig. 204 ). Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 411 ).

Etymology. "Socket of a ring for a jewel, bezel"; named in reference to the prosternal fovea.

Distribution. Currently known from three localities at three quite different elevations: central Area 1 (1100– 1300 m), eastern Area 2 (160 m), and far eastern Area 2 (900–1100 m) ( Fig. 527 ).

Figures

FIGURE 202. Hydraena pala, holotype, dorsal and lateral habitus, and venter.

FIGURE 207. Hydraena palamita, holotype, dorsal and lateral habitus, and venter.

FIGURES 204–205. Aedeagi of holotypes. 204. H. pala. 205. H. maculopala.

FIGURES 408–411. Female tergite X, gonocoxite, and spermatheca of Hydraena species.

FIGURES 527–530. Geographical distributions of Hydraena species.