Hydraena jubilata, 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 : 36-37

Hydraena jubilata , new species

( Figs. 42 , 44, 349–350 , 391 , 451 )

Type Material. Holotype (male): 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) ( NHM) . Paratypes (121): Eastern Highlands Province: Purosa Valley, nr. Okapa , on submerged stones, [GE est.] 1500–1700 m, 6° 32' S, 145° 37' E, 8 ii 1965, M. E. Bacchus (MEB 182a) (4 NHM) ; Umg. [=environs of] Onerunka, Ramu River , [GE est.] 1500–1700 m, 6° 20' S, 145° 47' E, 13 vi 1979, W. G. Ullrich (3 MHNG) ; Madang Province: Same data as holotype (65 NHM) ; Finisterre Mts., Naho River Valley, Budemu , ex sand and gravel banks of small stream, but only in the 20 yards that it is permanent, 1264 m, 5° 56' S, 146° 40' E, 19 x 1964, M. E. Bacchus (MEB 62) (3 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) (12 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) (20 NHM) ; 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) (3 NHM) ; 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) (6 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) (5 NHM) .

Differential Diagnosis. The habitus is similar to that of H. nitidimenta ( Figs. 42 , 43 ); distinguished therefrom and from the other members of the Jubilata group by the deep pronotal foveae PF2, the frons punctures being much coarser laterally than medially, and the comparatively short, tapering metaventral plaques. The metatibiae of males are straight in H. jubilata , and slightly arcuate in the three other members of the Jubilata group. The aedeagus ( Fig. 44) distinctively differs from that of other members of the Jubilata group. The metaventrite, abdominal apex, and chaetotaxy of the metatibiae are illustrated with SEMs ( Figs. 349–350 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.79/0.69; head 0.32/0.39; pronotum 0.43/0.48, PA 0.43, PB 0.39; elytra 1.05/0.69. Dorsum dark brown to piceous, except anterior ca. 1/6 of pronotum light brown, legs brown to slightly reddish brown; maxillary palpi brown to light brown.

Frons punctures much finer and sparser on disc than next to eyes, ca. 0.5xef on disc, 1.5xpd laterally; interstices shining, 1–6xpd on disc. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum similarly very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum cordiform, anterior margin very slightly emarginate, anterior angles sharply rounded; punctures on disc ca. 1xpd largest punctures of frons, interstices weakly shining, 2–4xpd, punctures larger and denser at anterior and posterior; PF1 shallow, separated by very low and indistinct midlongitudinal ridge; PF2 deep, oval, oblique, not confluent, separated by narrow ridge; PF3 deep; PF4 shallow.

Elytra transversely convex, summit of posterior declivity near or at midlength; lateral explanate margins narrow; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, 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 conjointly rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/3.5/2. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward apex, apex joined to mesoventral midlongitudinal ridge. Plaques moderately wide, tapering anteriorly, parallel, weakly raised, located at sides of deep, median depression. Metaventrite with short midlongitudinal ridge between mesoventral intercoxal process and median depression. AIS width at straight posterior margin very slightly greater than P2. All legs long and very slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia straight, with minute bump at apex on medial surface. Mesotibia straight. Metatibia straight, or nearly imperceptibly emarginate on medial surface in distal 1/2. Metatrochanter with minute tubercle (SEM Fig. 349 ). Abdominal apex symmetrical; last tergite (male) deeply notched.

Aedeagus ( Fig. 44) main piece, in ventral aspect, slightly sinuate, with both right and left sides thick-walled, left side characteristically with large lobate process apically; both parameres, in lateral aspect, lobe-shaped distally, right as wide as or wider than left; left paramere slightly longer than right; right paramere lobe-shaped in distal 2/3, setae along nearly entire ventral margin, none at apical angle. Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 391 ).

Etymology. "Joyfully shouting"; named in reference to the smile-shaped depression of the pronotum, formed by the PF2 foveae.

Distribution. Currently known from a moderately closely clustered group of localities in eastern Area 1 at 1500–1700 m, and Area 5 at 1080–1375 m ( Fig. 451 ). This is one of ten species with distributions exclusively shared between Areas 1 and 5 ( Fig. 422 ).

Figures

FIGURE 42. Hydraena jubilata, holotype, dorsal and lateral habitus, and venter.

FIGURE 43. Hydraena nitidimenta, holotype, dorsal and lateral habitus, and venter.

FIGURES 346–351. Scanning electron micrographs of H. impercepta (346–348), H. jubilata (349–350) and H. lassulipes (351).

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

FIGURES 451–454. 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.