Hydraena bubulla, 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 : 70

Hydraena bubulla , new species

( Figs. 111 , 113, 482 )

Type Material. Holotype (male): Madang Province: Akameku–Brahmin , Bismarck Range, 750 m, 5° 49.307' S, 145° 24.389' E, 25 xi 2006, Balke & Kinibel ( PNG 114) ( ZSM).

Differential Diagnosis. Immediately differentiated from other members of the Velvetina group by the densely micropunctulate dorsal surface of the head and pronotum ( Fig. 111 ). The metaventral tumid areas, on each side of the median depression, are another distinctive character of the species. The aedeagus cannot be confused with those of the other members of the group ( Fig. 113).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.72/0.68; head 0.25/0.39; pronotum 0.43/0.48, PA 0.41, PB 0.34; elytra 1.04/0.68. Dorsum piceous, except light brown band across anterior 1/6 of pronotum, legs brown to reddish brown, maxillary palpi testaceous to brown, distal 1/3 of last palpomere darker.

Frons and clypeus densely strongly micropunctulate, dull, punctures obscured, ca. 1xef. Mentum slightly concave, very sparsely very finely punctulate, shining; postmentum effacedly micropunctulate. Genae raised, shining, with tiny median impression, without posterior ridge. Pronotum cordiform, anterior margin straight or slightly arcuate; entirely densely micropunctulate, dull, punctures on disc obscured, ca. 1xpd those of frons, 2–4xpd, punctures slightly larger and denser at anterior and posterior; PF1 extending posteriorly in midlongitudinal impression between PF2; PF2 deep, large, oval, oblique, very shallowly confluent; PF3 deep; PF4 moderately deep.

Elytra convex, effacedly microreticulate, dull, summit of posterior declivity at or very near 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, 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 on markedly tumid area on each side of deep median depression. AIS width at straight posterior margin slightly greater than 2x P2. All legs moderately long and 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 several large spines, emargination with row of short spines, anterior margin slightly arcuate, widest at distal 2/3. Mesotibia straight. Metatibia straight. Abdominal apex symmetrical; last tergite (male) shallowly notched. Aedeagus ( Fig. 113) in ventral aspect with main piece comparatively narrow and left paramere not visible; in left lateral view large process of distal piece in front of left paramere. Female not yet known.

Etymology. "Big bubble"; named in reference to the large and strongly hydrofuge pubescent tumidities of the metaventrite, and the large bubble that would result from this morphology.

Distribution. Currently known only from the type locality in the Bismarck Range, in the eastern part of Area 2; elevation 750 m ( Fig. 482 ).

Figures

FIGURE 111. Hydraena bubulla, holotype, dorsal and lateral habitus, and venter.

FIGURES 479–482. Geographical distributions of Hydraena species.