Hydraena transvallis, 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 : 99-100

Hydraena transvallis , new species

( Figs. 171 , 173, 506 )

Type Material. Holotype (male): Madang Province: Finisterre Mts., Naho River Valley, Damanti , 1082 m, 5° 55' S, 145° 58' E, 2–7 x 1964, M. E. Bacchus (MEB 30) ( NHM) . Paratype: Simbu Province: NE, Karimui, south of Goroka , 1000 m, 6° 30' S, 144° 51' E, 5 vi 1961, J. L. & M. Gressitt (1 BPBM) .

Differential Diagnosis. Among members of the Cristatigena group, similar to H. inplacopaca and H. labropaca in the absence of metaventral plaques; differing from H. inplacopaca in the smaller size (ca. 1.68 vs. 2.07 mm), the less dense and slightly coarser pronotal punctation, and the less apparent dorsal setae ( Figs. 167 ,

170 , 171 ). Males of H. transvallis are differentiated from both species by the widened mesotibiae; and from H. labropaca by the differently shaped labrum. 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) 1.68/0.78; head 0.25/0.44; pronotum 0.41/0.57, PA 0.49, PB 0.48; elytra 1.04/0.78. 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 with deep V-shaped notch, anterior margin at sides of notch with tiny point, free margins very 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 ca. 1xpd or slightly larger 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 parallel, apex blunt. 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; mesotibia widened, widest part, slightly past midlength, wider than metatibia; metatibia very gradually widening from base to apex, very weakly arcuate. Abdominal apex symmetrical.

Aedeagus ( Fig. 173) 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 geographical distribution, two localities separated by extensive lowlands.

Distribution. Currently known from one locality in the southeastern part of Area 1, at the border with Area 13 (1000 m), and one locality in the Finisterre Mts., Area 5 at the border with Area 3 (1082 m) ( Fig. 506 ). This is one of ten species with distributions exclusively shared between Areas 1 and 5 ( Fig. 422 ).

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 503–506. 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.