Hydraena idema, 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 : 72-73

Hydraena idema , new species

( Figs. 118 , 120 , 480 )

Type Material. Holotype (male): Eastern Highlands Province: Umg. [=environs of] Onerunka, Ramu River , [GE est.] 1500–1700 m, 6° 20' S, 145° 47' E, 9 xii 1979, W. G. Ullrich ( MHNG) . Paratypes (2): Eastern Highlands Province: Umg. [=environs of] Igipinti, Korindaiop River, [GE est.] 600–1700 m, 6° 25' S, 145° 42' E, 18 vi 1979, W. G. Ullrich (1 MHNG); Wanitabi Valley , nr. Okapa, on partly rotted floating logs, 1524 m, 6° 32' S, 145° 37' E, 5 ii 1965, M. E. Bacchus (MEB 176a) (1 NHM) .

Differential Diagnosis. Among members of the Velvetina group, somewhat similar in habitus to H. incista ( Figs. 114 , 118 ), including having the pronotum length and width equal; differing therefrom by the larger size (ca. 1.89 vs. 1.71 mm), the lack of depressed areas on the frons, and the non-depressed mesoventral intercoxal process. The aedeagi of the two species distinctively differ ( Figs. 116 , 120 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.89/0.72; head 0.30/0.39; pronotum 0.47/0.47, PA 0.40, PB 0.37; elytra 1.11/0.72. Dorsum piceous, except light brown to testaceous band across anterior 1/5 of pronotum, legs and maxillary palpi brown to reddish brown.

Frons punctures ca. 1xef; interstices shining, 1–4xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, with tiny median impression, without posterior ridge. Pronotum cordiform, anterior margin straight or slightly arcuate; punctures on disc ca. 1xpd those of frons, interstices shining, 2–4xpd, punctures slightly larger and denser at anterior and posterior; PF1 absent; PF2 deep, large, oval, oblique, very shallowly confluent; PF3 deep; PF4 moderately deep.

Elytra convex, summit of posterior declivity slightly past midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior, some punctures random near base. Intervals not raised, shining, on disc ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming shallow angle with one another.

P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 2/1, sides slightly converging toward apex. Plaques absent, hydrofuge pubescence longest at sides of deep median depression. AIS width at straight posterior margin slightly greater than 2x P2. All legs long and very slender. Profemur (male) without tubercle next to trochanter; protibia straight, medial margin gradually widening from base to slightly past midlength, then emarginate to apex, widest point with large spine, emargination with row of short spines. Mesotibia straight. Metatibia straight, medial margin very slightly emarginate. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus ( Fig. 120 ) markedly arcuate in lateral view; distal piece with several processes. Females not yet known.

Etymology. Named in reference to the shape of the pronotum, which has the length and width equal. Distribution. Currently known from a cluster of localities in eastern Area 1; elevation 1500–1700 m, but with one locality estimated (using Google Earth) broadly at 600–1700 m ( Fig. 480 ).

Figures

FIGURE 114. Hydraena incista, holotype, dorsal and lateral habitus, and venter.

FIGURE 118. Hydraena idema, holotype, dorsal and lateral habitus, and venter.

FIGURES 120–121. Aedeagi of holotypes. 120. H. idema. 121. H. okapa.

FIGURES 479–482. Geographical distributions of Hydraena species.

FIGURES 116–117. Aedeagi of holotypes. 116. H. incista. 117. H. copulata.