Hydraena clarinis, 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 : 64-65

Hydraena clarinis , new species

( Figs. 99 , 101 , 476 )

Type Material. Holotype (male): Madang Province: Sepik Ramu Basin, Kojé Creek , unshaded creek, small to medium cobbles, gravel and fine sand (the latter in areas of slack water), filamentous algae on stony substrates, small accumulations of leaf litter, 160 m, 5° 33' S, 145° 23' E, 1 vii–30 viii 1988, D. Dudgeon ( NMW) . Paratypes: Same data as holotype (8 NMW) .

Differential Diagnosis. Differentiated from other members of the Colorata group by the small size (ca. 1.13 mm) and the clear pronotum, which does not have a macula or fascia ( Fig. 99 ). The testaceous pronotum is similar in color to that of H. ramuensis (which see), but otherwise the two species differ distinctively. The male genitalia bear some superficial similarity to that of H. colorata , but the two distinctively differ in many details ( Figs. 89 , 101 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.13/0.50; head 0.18/0.28; pronotum 0.29/0.36, PA 0.31, PB 0.32; elytra 0.67/0.50. Dorsum of head dark brown; pronotum testaceous to light brown, no macula or fascia; elytra brown; legs light brown to testaceous; maxillary palpi testaceous.

Frons punctures ca. 1xef; interstices shining, 2–5xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely and very finely punctulate, strongly shining. Genae very slightly raised, shining, without posterior ridge. Pronotum weakly cordiform, anterior margin slightly emarginate; punctures on disc ca. 1xpd those of frons, interstices shining, 1–3xpd, punctures slightly larger and denser at anterior and posterior; PF1 very shallow, almost obsolete; PF2 very shallow, oval, oblique, very shallowly confluent; PF3 moderately deep; PF4 absent.

Elytra with summit of posterior declivity before midlength; lateral explanate margins narrow; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–3xpd, 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. 3/1/3/3. P1 laminate; median carina sinuate in profile. P2 very slightly raised, l/w ca. 2/1, sides slightly converging toward apex. Plaques short, carinate, located at sides of deep, inverted V-shaped median depression. Metaventrite with very low midlongitudinal ridge between P2 and apex of median depression. AIS slightly concave, width at straight posterior margin ca. 1.5x P2. Profemur (male) with small, pointed tubercle next to trochanter; protibia slightly arcuate, medial margin in distal 1/2 slightly thickened and bearing row of very short, peg-like spines. Mesotibia straight. Metatibia very slightly, if at all, arcuate. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 101 ).

Etymology. Named in reference to the clear and bright pronotum.

Distribution. Currently known only from type locality, Kojé Creek in eastern Area 3; elevation 160 m ( Fig. 476 ).

Figures

FIGURE 99. Hydraena clarinis, holotype, dorsal and lateral habitus, and venter.

FIGURES 100–101. Aedeagi of holotypes. 100. H. nanocolorata. 101. H. clarinis.

FIGURES 475–478. Geographical distributions of Hydraena species.

FIGURES 88–89. Aedeagi of holotypes. 88. H. koma. 89. H. colorata.