Hydraena inplacopaca, 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 : 99

Hydraena inplacopaca , new species

( Figs. 170 , 172, 509 )

Type Material. Holotype (male): Eastern Highlands Province: Waisa, nr. Okapa , in holes in partly burnt and decayed logs in small fast river, 1524 m, 6° 38' S, 145° 32' E, 15 ii 1965, M. E. Bacchus (MEB 192) ( NHM) . Paratypes: Eastern Highlands Province: Wanitabi Valley, nr. Okapa , ex muddy gravel banks of small shaded stream, 1524 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 177a) (10 NHM) .

Differential Diagnosis. Among members of the Cristatigena group, similar to H. labropaca and H. transvallis in the absence of metaventral plaques; differing from both species in the larger size (ca. 2.07 vs. 1.62 and 1.68 mm), the less dense and slightly finer pronotal punctation, and the more apparent dorsal setae ( Figs. 167 , 170 , 171 ). Males additionally differ from H. transvallis by the simple mesotibiae, and from H. labropaca by the differently shaped labrum; differing from both species by the metafemur, having the basal 1/2 of the lower surface slightly emarginate and bearing a moderately dense patch of short, arcuate setae. The male genitalia of the three species share a basic form, but differ in several significant details ( Figs. 169, 172, 173).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.07/0.90; head 0.34/0.50; pronotum 0.49/0.66, PA 0.56, PB 0.54; elytra 1.23/0.90. Dorsum brown to dark brown, head and pronotal disc slightly darker, palpi light brown, except distal 1/2 of last palpomere darker.

Dorsum of head and pronotum densely punctulate, dull; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1xpd or slightly larger, each puncture with short fine seta; punctures of clypeus obsolete. Labrum apicomedially excised, free margins weakly upturned. Mentum finely, moderately densely punctate, shining; postmentum anterior 1/2 with punctation similar to mentum, posterior 1/2 densely micropunctulate. Genae raised, posterior ridge strong. Pronotum with anterior margin weakly emarginate over middle 1/2; emargination with very narrow hyaline margin; pronotal foveae PF1 and PF2 moderately deep, PF3 and PF4 very deep.

Elytra dull, punctures much larger and deeper than largest pronotal punctures, each puncture with short fine seta and three granules, one at anterior margin and one on each side. Intervals not raised, width ca. 1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another. Explanate margin well developed, about as wide as widest part of metatibia.

Metaventrite markedly tumid on each side of median impression, plaques absent, hydrofuge pubescence dense. P1 laminate; median carina sinuate in profile. P2 moderately narrow, l/w ca. 2/1, sides diverging very slightly to blunt apex. No midlongitudinal carina between mesoventral intercoxal process and median impression. AIS flat, width at straight posterior margin ca. 2x P2. Protibia (male) widened, weakly arcuate, medial surface flat or slightly concave; mesotibia simple; metafemur basal 1/2 of lower surface slightly emarginate and bearing moderately dense patch of short, arcuate setae; metatibia very gradually widening from base to apex, medial surface very slightly arcuate near midlength. Abdominal apex symmetrical.

Aedeagus ( Fig. 172) main piece with large distal lobe, in ventral aspect, weakly arching from right side toward left side, apically rounded, small lobe on left side; left paramere smaller than distal lobe, widest at midlength, with two small lobes, each with a cluster of setae; right paramere longer than and apically slightly narrower than distal lobe of main piece, apically blunt; distal piece, in right lateral view, with large lobe of characteristic shape.

Etymology. Named in reference to the lack of metaventral plaques, and dull dorsal sculpture.

Distribution. Currently known from two localities near Okapa, in the eastern part of Area 1; both of which are at about 1524 m ( Fig. 509 ).

Figures

FIGURE 167. Hydraena labropaca, holotype, dorsal and lateral habitus, and venter.

FIGURE 170. Hydraena implacopaca, holotype, dorsal and lateral habitus, and venter.

FIGURE 171. Hydraena transvallis, holotype, dorsal and lateral habitus, and venter.

FIGURES 507–510. Geographical distributions of Hydraena species.