Hydraena perpunctata Perkins 2011, new species

(Figs. 155, 157, 500)

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).

Differential Diagnosis. The coarse and dense dorsal punctation is similar to, though even coarser than, that of H. austrobesa and H. limbobesa (Figs. 150, 151, 155). In addition to the coarser punctation, H. perpunctata additionally differs from the compared species by the more angulate sides of the pronotum, the wider explanate margin of the elytra, and the narrower and more widely separated metavental plaques (ratios ca. 6/1/4/10). The aedeagus of H. perpunctata (Fig. 157) is abundantly distinct from that of other members of the Spinobesa group, and perhaps represents a separate species group.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.37/0.71; head 0.25/0.37; pronotum 0.38/0.52, PA 0.41, PB 0.41; elytra 0.87/0.71. Dorsum of head piceous; pronotum light brown to testaceous in front of and behind piceous fascia with ill-defined margins, ratios of color bands, as measured in midline, ca. 7/12/6; elytra and legs brown; maxillary palpi light brown to testaceous, tip not darker.

Frons coarsely densely punctate, punctures ca. 3–4xef, slightly larger and denser near eyes than medially; interstices microreticulate and dull laterally, effacedly microreticulate and weakly shining medially, narrow walls to 1xpd. Clypeus microreticulate laterally, moderately coarsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum moderately transverse (PL/PW ca. 0.73), ca. median 3/5 of anterior margin slightly emarginate; very coarsely, densely punctate, punctures on disc ca. 3xpd frons punctures, interstices on disc shining, narrow walls to 1xpd, punctures larger and denser at anterior and posterior; PF1 shallow, obsolete; PF2 moderately deep; PF3 deep; PF4 shallow.

Elytra with summit of posterior declivity slightly anterior to midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, weakly shining, on disc ca. 1xpd, 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. 6/1/4/10. P1 laminate; median carina sinuate in profile. P2 very narrow, raised slightly, l/w ca. 2/1, sides slightly converging toward apex. Plaques minute, widely separated, carinate lines at sides of median depression that continues shallowly to tip of P2. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin slightly wider than P2. All legs rather short, femora moderately robust. Profemur (male) without tubercle next to trochanter; protibia widest at distal 1/3 where produced on medial margin. Mesotibia straight, lateral margin slightly arcuate and bearing row of short stout spines. Metatibia missing in holotype. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus as illustrated (Fig. 157).

Etymology. Named in reference to the very coarse dorsal punctation.

Distribution. Currently known only from the type locality, Kojé Creek, in the eastern arm of Area 3; elevation 160 m (Fig. 500).