Hydraena palamita, 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 : 116

Hydraena palamita , new species

( Figs. 207 , 209, 533 )

Type Material. Holotype (male): Central Province: nr. Port Moresby, Sogeri Plateau, Musgrave River , river, [GE est.] 100–200 m, 9° 46' S, 147° 41' E, 16 iii 1965, M. E. Bacchus (MEB 200) ( NHM) . Paratypes (35): Central Province: nr . Port Moresby, Sogeri Plateau, Musgrave River , ex gravel banks, [GE est.] 100–200 m, 9° 46' S, 147° 41' E, 16 iii 1965, M. E. Bacchus (MEB 200a) (31 NHM) ; Madang Province: Ramu Valley , 2 km SE Brahman, [GE est.] 130–150 m, 5° 43' S, 145° 22' E, 18 iv 1991, D. Larson (1 MCZ) ; Sandaun Province: Mianmin , river, 990 m, 4° 54.57' S, 141° 35.49' E, 23 x 2008, S. Ibalim ( PNG 192) (1 ZSM) ; Mianmin , river, 1080 m, 4° 55.78' S, 141° 38.185' E, 24 x 2008, S. Ibalim ( PNG 195) (2 ZSM) .

Differential Diagnosis. Very similar in color, body form and dorsal sculpture to H. pala ( Figs. 202 , 207 ); differing therefrom in the slightly smaller size (ca. 1.47 mm vs. 1.58) and the slightly more narrowly separated plaques (ratios ca. 6/1/6/5 vs. 6/1/6/6). 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) 1.47/0.60; head 0.26/0.32; pronotum 0.33/0.46, PA 0.36, PB 0.37; elytra 0.86/0.60. Dorsum of head dark brown to reddish brown; pronotum light brown to testaceous; elytra dark brown to reddish brown, with faint light brown macula at posterior declivity; legs brown to light reddish brown; maxillary palpi light brown to 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 and postmentum very sparsely very finely punctulate, shining. 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 absent or 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. 6/1/6/5. P1 ca. 2/3 P2; median carina straight in profile; postcoxal process medially concave. P2 transversely concave, l/w ca. equal, sides slightly diverging toward blunt apex. Plaques very narrow, carinate, parallel, at sides of deep median depression. Metaventrite concave between P2 and plaques. AIS width at straight posterior margin ca. equal P2. All legs long and slender. Profemur (male) without tubercle next to trochanter; protibia straight, anterior margin very slightly widened subapically. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) deeply notched, each side of notch produced in point. Aedeagus as illustrated ( Fig. 209).

Etymology. "Pala's father's sister"; named in reference to the relationship to H. pala .

Distribution. Currently known from three widely disjunct areas: Mianmin area (Area 1 or 2; 990–1080 m), Ramu Valley (Area 2 or 3; 130–150 m), and near Port Moresby (Area 11; 100–200 m) ( Fig. 533 ).

Figures

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

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

FIGURES 531–534. Geographical distributions of Hydraena species.

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