Hydraena pertransversa, 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 : 90

Hydraena pertransversa , new species

( Figs. 154 , 156 , 497 )

Type Material. Holotype (male): Eastern Highlands Province: Clear stream, summit of Kassem Pass at forest level, 1450 m, 6° 18' S, 145° 52' E, 27 vii 1975, R. W. Hornabrook ( NMNZ) . Paratypes (5): Eastern Highlands Province: Same data as holotype (1 NMNZ) ; Western Highlands Province: Simbai , 1800–2000 m, 5° 14.276' S, 144° 28.741' E, 1 iii 2007, Kinibel ( PNG 138) (4 ZSM) .

Differential Diagnosis. Similar in dorsal sculpture to H. owenobesa ( Figs. 146 , 154 ); differentiated therefrom by the longer elytra with more acuminate apices (PL/EL ca. 0.32 vs. 0.37), the more transverse pronotum (PL/PW ca. 0.64 vs. 0.67), and the smaller metaventral plaques (ratios ca. 1/1/1/4 vs. 1/1/5/4). The aedeagi of the two species greatly differ ( Figs. 148 , 156 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.54/0.66; head 0.25/0.35; pronotum 0.32/0.50, PA 0.40, PB 0.42; elytra 0.99/0.66. Dorsum dark brown to piceous; legs brown; maxillary palpi light brown, tip not darker.

Frons punctures ca. 1xef, slightly larger and denser near eyes than medially; interstices microreticulate and dull laterally, effacedly microreticulate and weakly shining medially, 1–3xpd. Clypeus microreticulate laterally, finely, sparsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum transverse (PL/PW ca. 0.64), ca. median 3/5 of anterior margin very slightly emarginate; coarsely, densely punctate, punctures on disc ca. 3xpd frons punctures, interstices on disc effacedly microreticulate, weakly shining, 1–2xpd, interstices microreticulate and dull in impressions, punctures 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 narrow; 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. 1–2xpd, 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. 1/1/1/4. P1 laminate; median carina sinuate in profile. P2 very narrow, raised slightly, l/w ca. 6/1, sides slightly converging toward apex. Plaques very small ovals, located basally at sides of median depression, depression does not continue anteriorly to tip of P2. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 5xP2. All legs rather short, femora moderately robust. Profemur (male) without tubercle next to trochanter; protibia widest subapically, medial margin very slightly emarginate, lateral margin weakly arcuate and bearing short stout spines in widest part. Mesotibia straight, gradually increasing in width from base to apex, lateral margin bearing row of short stout spines. Metatibia straight, gradually increasing in width from base to apex, medial margin with few moderately long setae in distal 1/3, lateral margin with some short spines in distal 1/2. Abdominal apex symmetrical; last tergite (male) notched. Aedeagus as illustrated ( Fig. 156 ).

Etymology. Named in reference to the very transverse prothorax.

Distribution. Currently known from two localities in the eastern part of Area 1, very near the border with Area 2; elevation range 1450–2000 m ( Fig. 497 ).

Figures

FIGURE 146. Hydraena owenobesa, holotype, dorsal and lateral habitus, and venter.

FIGURE 154. Hydraena pertransversa, holotype, dorsal and lateral habitus, and venter.

FIGURES 156–157. Aedeagi of holotypes. 156. H. pertransversa. 157. H. perpuncta.

FIGURES 495–498. Geographical distributions of Hydraena species.

FIGURES 148–149. Aedeagi of holotypes. 148. H. owenobesa. 149. H. saluta.