Hydraena insandalia, 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 : 53

Hydraena insandalia , new species

( Figs. 74 , 76 , 462 )

Type Material. Holotype (male): Eastern Highlands Province: Headwaters of Fio River, 0.5 km downstream of river crossing on Herowana / Oke Lookout path, ca. 4.5 km N of Herowana airstrip, washed from margins of riverside still water pools in rainforest; gravel and cobble dominated microhabitats, but some muddy, 1500 m, 6° 35' S, 145° 11' E, 29 v 2004, N. Porch ( ANIC) . Paratypes: Same data as holotype (25 ANIC) .

Differential Diagnosis. Similar to H. aulaarta in habitus and some male sexual dimorphisms (tubercle on first abdominal ventrite ( Figs. 74 , 82 ); differentiated therefrom by the larger size (ca. 1.81 vs. 1.64 mm), the slanting plaques, and, in males, the differently shaped pro- and metatibiae, and the meso- and metatarsi without long hairlike setae. Some of these differences are subtle; reliable determinations of the two species will require examination of the aedeagi, which distinctively differ ( Figs. 76 , 84 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.81/0.69; head 0.31/0.37; pronotum 0.41/0.48, PA 0.43, PB 0.39; elytra 1.06/0.69. Dorsum piceous; legs and maxillary palpi dark brown.

Frons punctures ca. 1xef, slightly larger and denser near eyes than medially; interstices shining, 1–6xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Pronotum cordiform, median 2/3 of anterior margin emarginate; punctures on disc ca. 1xpd those of frons, interstices shining, 2–6xpd, punctures slightly larger and denser at anterior and posterior; PF1 absent; PF2 very shallow, obsolete; PF3 deep; PF4 absent.

Elytra with summit of posterior declivity slightly past midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, some punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 2–3xpd, 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. 3/4/13/1. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward blunt apex. Plaques very large, very narrowly separated, slightly more narrowly separated posteriorly than anteriorly, weakly raised, slightly more so laterally than medially. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 1.7x P2. All legs long and very slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia straight or very slightly arcuate, distal 1/4 widened on anterior surface, with cluster of short spines medially, moderately long spine on medial surface at base of widened area. Meso- and metatibia straight. First abdominal ventrite with large, sharply pointed tubercle in midline. Fifth abdominal ventrite simple. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 76 ).

Etymology. "Without sandals"; named in reference to the lack of a large brush of setae on the tarsi.

Distribution. Currently known only from the type locality in eastern Area 1, at 1500 m ( Fig. 462 ).

Figures

FIGURE 74. Hydraena insandalia, holotype, dorsal and lateral habitus, and venter.

FIGURE 82. Hydraena aulaarta, holotype, dorsal and lateral habitus, and venter.

FIGURES 76–77. Aedeagi of holotypes. 76. H. insandalia. 77. H. biundulata.

FIGURES 459–462. Geographical distributions of Hydraena species.

FIGURES 84–85. Aedeagi of holotypes. 84. H. aulaarta. 85. H. altapapua.