Hydraena supersexa, 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 : 80-81

Hydraena supersexa , new species

( Figs. 134 , 136, 328–333 , 405 , 493 )

Type Material. Holotype (male): Eastern Highlands Province: Okapa , ex muddy gravel banks of fast, clear stream, 1524 m, 6° 32' S, 145° 37' E, 9 ii 1965, M. E. Bacchus (MEB 183) ( NHM) . Paratypes (336): Eastern Highlands Province: Same data as holotype (4 NHM) ; Okapa , on wet rocks above waterline, fast, clear stream, 1524 m, 6° 32' S, 145° 37' E, 9 ii 1965, M. E. Bacchus (MEB 183a) (2 NHM) ; Wanitabi Valley, nr. Okapa , ex dead leaves caught among rocks in small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171b) (3 NHM) ; Wanitabi Valley, nr. Okapa , gravel banks of small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171a) (7 NHM) ; Wanitabi Valley, nr. Okapa , on wet rocks above waterline in small swift river, 1372 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 171c) (2 NHM) ; Madang Province: Finisterre Mts., Naho River Valley, Budemu , ex gravel banks of large river, 1264 m, 5° 56' S, 146° 40' E, 18 x 1964, M. E. Bacchus (MEB 61) (23 NHM) ; Finisterre Mts., Naho River Valley, Budemu –Kikipei track, ex gravel banks of small stream, 1220 m, 5° 56' S, 146° 40' E, 24 x 1964, M. E. Bacchus (MEB 74) (1 NHM) ; Finisterre Mts., Naho River Valley, Budemu –Kikipei track, ex gravel bank of small river in places where rotten leaves had accumulated, 1220 m, 5° 56' S, 146° 40' E, 24 x 1964, M. E. Bacchus (MEB 73) (3 NHM) ; Finisterre Mts., Naho River Valley, Moro , 1691 m, 5° 50' S, 146° 7' E, 30 x–23 xi 1964, M. E. Bacchus (MEB 78) (68 NHM) ; Finisterre Mts., Naho River Valley, Moro , nr. Sewe , gravel bank of small stream running into River Naho , 1372 m, 5° 50' S, 146° 7' E, 2 xi 1964, M. E. Bacchus (MEB 81) (70 NHM) ; Finisterre Mts., Naho River Valley, Moro , small stream running into River Naho , ex crevices in vertical rock, heavy water flow, 1372 m, 5° 50' S, 146° 7' E, 2 xi 1964, M. E. Bacchus (MEB 80) (97 NHM) ; Finisterre Mts., Naho River Valley, nr. Moro , ex dead leaves and muddy gravel by small stream, 1372 m, 5° 50' S, 146° 7' E, 5 xi 1964, M. E. Bacchus (MEB 88) (25 NHM) ; Finisterre Mts., Naho River Valley, nr. Moro , ex gravel banks of small fast stream, 1432 m, 5° 50' S, 146° 7' E, 7 xi 1964, M. E. Bacchus (MEB 91) (16 NHM) ; Finisterre Mts., Naho River Valley, nr. Moro , ex tiny puddles left in clay bottom of partly ephemeral pool, 1432 m, 5° 50' S, 146° 7' E, 7 xi 1964, M. E. Bacchus (MEB 92) (5 NHM) ; Finisterre Mts., Naho River Valley, nr. Sewe , large flat area of wet gravel with small rivulets running through it, 1615 m, 5° 51' S, 146° 8' E, 15 xi 1964, M. E. Bacchus (MEB 95) (10 NHM) .

Differential Diagnosis. Males differentiated from other species, except the putative sister species H. sexsuprema , by the strongly arcuate meso- and metatibiae; females recognized by the concave frons ( Figs. 134 , 135 ). Males differentiated from those of H. sexsuprema by the slightly larger size (ca. 1.86 vs. 1.78 mm), the markedly widened tips of the mesotibiae, the lack of a brush of setae on the metatibiae, and the longer, more narrowly separated plaques (ratios ca. 4/1/8/6 vs. 4/1/6/8). The male genitalia of the two species share a basic plan, but differ distinctively in shapes of the parameres, among other features ( Figs. 136, 137). The exocrine pore areas of the female head and pronotum, as well as the structure of the metaventrite, abdominal apex, and very complicated chaetotaxy of the tibiae are illustrated with SEMs ( Figs. 328–333 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.86/0.80; head 0.31/0.44; pronotum 0.46/0.55, PA 0.47, PB 0.46; elytra 1.12/0.80. Dorsum dark brown to piceous; legs and maxillary palpi dark brown.

Frons markedly microreticulate, except effacedly microreticulate. on middle of disc, punctures ca. 1xef; interstices 1–5xpd. Clypeus microreticulate laterally, finely, moderately sparsely punctate medially. Mentum very sparsely very finely punctulate, strongly shining; postmentum medially micropunctulate, moderately dull. Genae raised, shining, without posterior ridge. Pronotum cordiform, median 2/3 of anterior margin emarginate; microreticulate, more strongly laterally and in PF2 than on disc; punctures on disc ca. 1–2xpd largest punctures of frons, interstices dull, 1–2xpd, punctures slightly larger and denser at posterior; PF1 absent or extremely shallow; PF2 deep, very shallow confluent; PF3 deep; PF4 moderately deep.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, some punctures random, punctures becoming gradually smaller toward posterior. Intervals not raised, weakly shining, on disc ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect weakly separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 4/1/8/6. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 3/2, sides slightly converging toward apex. Plaques carinate, very narrow, located at sides of deep, wide median depression. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 1.5x P2. All tibiae strongly arcuate, especially meso- and metatibiae. Profemur (male) with small, sharply pointed tubercle on medial surface short distance from trochanter. Mesotibia markedly widened in distal 1/4, widest and with small tubercle subapically. Metatibia without brush of setae. Abdominal apex slightly asymmetrical; last tergite (male) deeply notched. Aedeagus ( Fig. 136), in ventral view, with sharp ridge on proximal part of main piece; distal piece large and complex; left paramere in lateral aspect very wide, with setae along distal margin, ventral margin with tight cluster of long, wavy setae. Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 405 ).

Etymology. Named in reference to the markedly sexually dimorphic legs and head, and to the relationship to H. sexsuprema .

Distribution. Currently known from eastern Area 1 and the Finisterre Mts. in Area 5; elevation range 1220– 1691 m ( Fig. 493 ). This is one of ten species with distributions exclusively shared between Areas 1 and 5 ( Fig. 422 ).

Figures

FIGURE 134. Hydraena supersexa, holotype, dorsal and lateral habitus, and venter.

FIGURE 135. Hydraena sexsuprema, holotype, dorsal and lateral habitus, and venter.

FIGURES 328–333. Scanning electron micrographs of H. supersexa.

FIGURES 404–407. Female tergite X, gonocoxite, and spermatheca of Hydraena species.

FIGURES 491–494. Geographical distributions of Hydraena species.

FIGURES 421–422. 421. All known collecting localities for Papua New Guinea Hydraena. 422. Ten species, representing eight species groups, with distributions exclusively shared between Areas of Endemism 1 and 5.