Hydraena tritutela, 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 : 96-97

Hydraena tritutela , new species

( Figs. 163 , 165, 412 , 512 )

Type Material. Holotype (male): Morobe Province: ca. 10 km S Garaina Saureri , 1600 m, 7° 55' S, 147° 5' E, 24 iii 1998, A. Riedel ( NMW) . Paratypes: Same data as holotype (79 NMW) .

Differential Diagnosis. Among members of the Cristatigena group that lack micropunctulate ground sculpture of the head and pronotum, most similar to H. bacchusi ; differing therefrom by the larger size (ca. 1.83 vs. 1.67 mm), the more elongate elytra that are more sharply rounded apically and have larger granules on the serial punctures ( Figs. 162 , 163 ). In addition, the male hind tibiae are shaped differently in the two species. The male genitalia of the two species, while differing distinctively in several details, have a general shape that suggests relationship ( Figs. 164, 165).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.83/0.81; head 0.29/0.46; pronotum 0.43/0.60, PA 0.48, PB 0.48; elytra 1.13/0.81. Dorsum very dark brown to piceous, palpi brown, except distal 1/2 of last palpomere slightly darker.

Dorsum of head and pronotum densely punctate, interstices shining; punctures of frons disc and pronotal disc 1–2xef, interstices varying, 0.5–2xpd, usually about 1xpd; punctures of clypeus distinct, smaller than punctures of frons. Labrum apicomedially excised, lobes rounded, free margins slightly upturned. Mentum sparsely punctate, shining; postmentum anterior 1/2 with punctation similar to mentum, posterior 1/2 densely micropunctulate. Genae raised, posterior ridge strong. Anterior margin of pronotum very weakly emarginate over middle 1/2; all pronotal foveae moderately deep, PF3 and PF4 deeper than other foveae.

Elytra weakly shining, punctures 1–2xpd of largest pronotal punctures, each puncture with three granules, one at anterior margin and one on each side. Intervals not raised, width ca. 0.5–1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly, moderately sharply rounded, in posterior aspect margins not forming angle with one another. Explanate margin well developed, about as wide as widest part of metatibia.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/7/6. P1 laminate; median carina sinuate in profile. P2 moderately narrow, l/w ca. 2/1, sides parallel, apex blunt. Plaques very narrow, posteriorly carinate, more widely separated posteriorly than anteriorly, non-arcuate, located at lateral margins of deep, median depression. Metaventrite tumid lateral to plaques. No midlongitudinal carina between mesoventral intercoxal process and plaques. Hydrofuge pubescence dense. AIS flat, width at straight posterior margin ca. 2x P2. Protibia (male) widened, medial surface rather flat, emarginate in distal 1/3; mesotibia slightly emarginate on medial surface in distal 1/2; metatibia bent at about distal 1/3, in lateral view distinctly widened from about midlenth to apex, apical widened area with small brush of setae on upper rim. Abdominal apex symmetrical.

Aedeagus ( Fig. 165) main piece with small distal lobe, in ventral aspect apically produced in two small lobes; left paramere large, larger than distal lobe of main piece, markedly bilobed, each lobe with cluster of setae; right paramere large, widest in distal 1/2, apically rounded, in right lateral aspect markedly arcuate toward ventral surface, setae in two clusters; distal piece with characteristic shape.

Etymology. "Three guards"; named in reference to the three granules around each elytral puncture.

Distribution. Currently known only from the type locality near Garaina Saureri, in the northwestern part of Area 7; elevation 1600 m ( Fig. 512 ).

Notes. In females the last maxillary palpomere is slightly smaller than in males, and the pronotal foveae, especially PF3 and PF4, are larger and deeper than in males.

Figures

FIGURE 162. Hydraena bacchusi, holotype, dorsal and lateral habitus, and venter.

FIGURE 163. Hydraena tritutela, holotype, dorsal and lateral habitus, and venter.

FIGURES 412–415. Female tergite X, gonocoxite, and spermatheca of Hydraena species.

FIGURES 511–514. Geographical distributions of Hydraena species.