Hydraena phainops, 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 : 31-32

Hydraena phainops , new species

( Figs. 31 , 33 , 296–297 , 322–323 , 390 , 445 )

Type Material. Holotype (male): Morobe Province: Lae–Bulolo road, Patep Creek , ex gravel bank of large fast river, [GE est.] 900–1100 m, 6° 52' S, 146° 37' E, 28 xii 1964, M. E. Bacchus (MEB 126) ( NHM) . Paratypes (186): Central Province: nr . Port Moresby, Sogeri Plateau, Musgrave River , ex dead leaves caught among rocks, [GE est.] 100–200 m, 9° 46' S, 147° 41' E, 16 iii 1965, M. E. Bacchus (MEB 200b) (6 NHM) ; Port Moresby – Brown River road, ex gravel banks of large slow muddy river, [GE est.] 50–100 m, 9° 24' S, 147° 14' E, 15 iii 1965, M. E. Bacchus (MEB 198) (3 NHM) ; Port Moresby – Brown River road, ex gravel banks of small fast running stream, [GE est.] 50–100 m, 9° 24' S, 147° 14' E, 15 iii 1965, M. E. Bacchus (MEB 199a) (1 NHM) ; East Sepik Province: Prince Alexander Mts., Wewak–Maprik , 100 m, 3° 43.013' S, 143° 37.665' E, 21 iv 2006, Balke ( PNG 47) (5 ZSM) ; Madang Province: Finisterre Mts., Naho River Valley , Damanti, ex gravel banks of small fast river ,

1082 m, 5° 55' S, 145° 58' E, 8 x 1964, M. E. Bacchus (MEB 37) (2 NHM) ; Highway near Madang, ford , 80 m, 5° 24.405' S, 145° 38.213' E, 26 xi–3 xii 2006, Binatang Boys ( PNG 117) (8 MCZ, NHM, NMW, PNG, ZSM); Keki, Adelbert Mts ., 400 m, 4° 43.058' S, 145° 24.437' E, 29 xi 2006, Binatang Boys ( PNG 119) (3 ZSM) ; Keki –Sewan, Adelbert Mts ., 300 m, 4° 40.558' S, 145° 27.187' E, 30 xi 2006, Binatang Boys ( PNG 121) (19 MCZ, NHM, NMW, PNG, ZSM); 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 (7 NMW) ; Morobe Province: 5 miles W of Lae, Buins Creek , ex sand and gravel banks of clear fast river, [GE est.] 10–40 m, 6° 43' S, 147° 2' E, 28 xii 1965, M. E. Bacchus (MEB 121) (68 NHM) ; c. 3 m. Lae–Busu road, ex gravel banks of small swift river, [GE est.] 50–70 m, 6° 41' S, 147° 0' E, 21 i 1965, M. E. Bacchus (MEB 155a) (14 NHM) ; c. 7 mi. Lae – Bulolo road, ex gravel and grass roots on bank of small stream, [GE est.] 10–30 m, 6° 41' S, 146° 54' E, 30 xii 1964, M. E. Bacchus (MEB 120) (8 NHM) ; Huon Pen. , road to Kwapsanek , 250 m, 6° 30.27' S, 146° 59.581' E, 31 iii 2006, Balke & Sagata ( PNG 24) (7 MCZ, NHM, NMW, PNG, ZSM); Kassam Pass, Sing Sing Creek , [GE est.] 1300–1500 m, 6° 12' S, 146° 1' E, 14 vi 1979, W. G. Ullrich (5 MHNG) ; Kassam Pass, Yung Creek , [GE est.] 1300–1500 m, 6° 12' S, 146° 0' E, 14 vi 1979, W. G. Ullrich (2 MHNG) ; Lae–Bulolo road, ex mud and muddy gravel by small shaded creek, [GE est.] 900–1100 m, 6° 50' S, 146° 37' E, 30 xii 1964, M. E. Bacchus (MEB 135) (1 NHM) ; Lae–Bulolo road, ex stones and gravel bank of large river, [GE est.] 900–1100 m, 6° 52' S, 146° 37' E, 28 xii 1964, M. E. Bacchus (MEB 124) (1 NHM) ; Lae– Bulolo road, Patep Creek , ex gravel bank of large fast river, [GE est.] 900–1100 m, 6° 52' S, 146° 37' E, 28 xii 1964, M. E. Bacchus (MEB 126) (4 NHM) ; Lae–Bulolo road, Peracles Creek , ex gravel banks of small steam, [GE est.] 900–1100 m, 6° 50' S, 146° 37' E, 30 xii 1964, M. E. Bacchus (MEB 132) (3 NHM) ; Lae, Umg. [=environs of] Oomsis, Buang River , [GE est.] 20–30 m, 6° 53' S, 146° 57' E, 14 vi 1979, W. G. Ullrich (17 MHNG) ; same locality, 15 vii 1979, W. G. Ullrich (1 MHNG) ; Markham Valley, Lae–Kainantu road, Erap River , ex gravel, [GE est.] 80–130 m, 6° 37' S, 146° 42' E, 26 i 1965, M. E. Bacchus (MEB 156) (1 NHM) .

Differential Diagnosis. Differentiated from other PNG members of the genus by the combination of the very small size (ca. 1.25 mm), the dark dorsum, and especially the very large metaventral plaques ( Figs. 31 , 296 ). The aedeagus distinctly differs from that of other members of the Manulea group ( Fig. 33 ). The metaventrite, and the very complicated chaetotaxy of the tibiae are illustrated with SEMs ( Figs. 296–297 , 322–323 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.25/0.52; head 0.21/0.32; pronotum 0.29/0.38, PA 0.34, PB 0.33; elytra 0.76/0.52. Dorsum of head piceous; pronotum piceous except anterior margin slightly lighter; elytra dark brown; legs and maxillary palpi brown, tip of palpus 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, median 2/3 of anterior margin emarginate; punctures on disc ca. 1xpd those of frons, interstices shining, 2–5xpd, punctures slightly larger and denser at anterior and posterior; PF1 absent; PF2 very shallow, obsolete; PF3 moderately deep; PF4 absent.

Elytra with posterior declivity very gradual, summit slightly past midlength; lateral explanate margins narrow; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–3xpd, as are interstices between punctures of a row, a few punctures subserial. 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. 3/4/8/1. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides converging toward blunt apex. Plaques very large, very narrowly separated, more narrowly so at posterior than at anterior, weakly raised. Metaventrite anteriorly with very low midlongitudinal ridge. AIS width at straight posterior margin ca. 1.7x P2. All legs moderately long and slender. Profemur (male) without tubercle next to trochanter; protibia very slightly arcuate, gradually increasing in width from base to apex. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus as illustrated ( Fig. 33 ). Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 390 ).

Etymology. "Bright eyes"; named in reference to the large, oval and brightly shining metaventral plaques.

Distribution. A wide distribution pattern, from the western part of Area 4 to the southeastern part of Area 11, and including records in Areas 2, 3, and 5, but no records from Area 1; elevation range 10–1500 m, but with only two records above 1100 m ( Fig. 445 ).

Figures

FIGURE 31. Hydraena phainops, holotype, dorsal and lateral habitus, and venter.

FIGURES 32–33. Aedeagi of holotypes. 32. H. thumbelipes. 33. H. phainops.

FIGURES 292–297. Scanning electron micrographs of H. foliobba (292–295) and H. phainops (296–297).

FIGURES 322–327. Scanning electron micrographs of H. phainops (322–323) and H. okapa (324–327).

FIGURES 388–391. Female tergite X, gonocoxite, and spermatheca of Hydraena species.

FIGURES 443–446. Geographical distributions of Hydraena species.