Hydraena reticulobesa, 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 : 86

Hydraena reticulobesa , new species

( Figs. 143 , 145 , 499 )

Type Material. Holotype (male): Madang Province: Finisterre Mts., Naho River Valley, Moro , 1691 m, 5° 50' S, 146° 7' E, 30 x–23 xi 1964, M. E. Bacchus (MEB 78) ( NHM) . Paratypes (11): Gulf Province: Marawaka , near Ande, 1000 m, 7° 3.598' S, 145° 44.375' E, 10 xi 2006, Balke & Kinibel ( PNG 89) (1 ZSM) ; Morobe Province: ca. 10 km S Garaina Saureri , 1600 m, 7° 55' S, 147° 5' E, 24 iii 1998, A. Riedel (9 NMW) ; Western Highlands Province: Lugup River , 1700 m, 5° 17.237' S, 144° 28.214' E, 4 iii 2007, Kinibel ( PNG 143) (1 ZSM) .

Differential Diagnosis. Similar in size (ca. 1.47 mm) and body proportions to H. owenobesa ( Figs. 143 , 146 ); differentiated therefrom by the entirely markedly microreticulate pronotum, the smaller metaventral plaques (ratios ca. 1/1/2/4 vs. 1/1/5/4), and the narrower and slightly longer P2. The aedeagi of the two species have some general plan similarities, but distinctively differ in many details ( Figs. 145 , 148 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.47/0.66; head 0.22/0.37; pronotum 0.34/0.51, PA 0.40, PB 0.43; elytra 0.92/0.66. Dorsum dark brown to piceous; legs brown; maxillary palpi light brown, tip slightly darker.

Frons punctures ca. 1xef, slightly larger and denser near eyes than medially; interstices markedly microreticulate laterally, dull, effacedly microreticulate medially, very weakly shining, 1–4xpd medially. Clypeus microreticulate laterally, finely, moderately densely punctate medially. Mentum and postmentum very sparsely finely punctulate, shining. Genae raised, shining, without posterior ridge. Pronotum transverse (PL/PW ca. 0.67), ca. median 3/5 of anterior margin very slightly emarginate; markedly microreticulate, dull, punctures on disc ca. 1– 2xpd frons punctures, interstices on disc 1–3xpd, punctures slightly denser at anterior and posterior; sculpture laterally markedly microreticulate, punctures obscured; PF1 shallow; PF2 deep, lateral margins roundly raised, shallowly confluent medially; PF3 and PF4 deep.

Elytra with summit of posterior declivity slightly anterior to midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly larger than 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. 1/1/2/4. P1 laminate; median carina sinuate in profile. P2 very narrow, raised slightly at tip, l/w ca. 6/1, sides slightly converging toward apex. Plaques very small and indistinct ovals basally at sides of median depression that does not continue anteriorly to tip of P2. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 3xP2. All legs rather short, femora moderately robust. Profemur (male) without tubercle next to trochanter; protibia widest at distal 1/3, medial margin slightly emarginate at midlength, lateral margin arcuate, ventral margin bearing short stout spines in widest part. Mesotibia straight, lateral margin slightly arcuate, lateral and ventral margins each bearing row of short stout spines. Metatibia very weakly, if at all, arcuate, 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. 145 ).

Etymology. Named in reference to the markedly microreticulate dorsum, and broad body form.

Distribution. Currently known from Areas 1, 5, and 7; elevation range 1000–1700 m, with one locality below and three localities at or above 1600 m ( Fig. 499 ).

Figures

FIGURE 143. Hydraena reticulobesa, holotype, dorsal and lateral habitus, and venter.

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

FIGURES 144–145. Aedeagi of holotypes. 144. H. spinobesa. 145. H. reticulobesa.

FIGURES 499–502. Geographical distributions of Hydraena species.

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