Hydraena torosopala, 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 : 118-119

Hydraena torosopala , new species

( Figs. 214 , 216, 532 )

Type Material. Holotype (male): Madang Province: Keki , Adelbert Mts., 400 m, 4° 43.058' S, 145° 24.437' E, 29 xi 2006, Binatang Boys ( PNG 119) ( ZSM).

Differential Diagnosis. Similar to H. tritropis in dorsal color and plaque ratios; differing therefrom by the larger size (1.45 vs. 1.29 mm), the proportionally smaller pronotum (PW/EL ca. 0.62 vs. 0.66), and the concave prosternal intercoxal process ( Figs. 211 , 214 ). The male genitalia of the two species distinctively differ ( Figs. 213 , 216).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.45/0.69; head 0.22/0.36; pronotum 0.36/0.53, PA 0.39, PB 0.43; elytra 0.86/0.69. Dorsum of head with frons dark brown to dark reddish brown, clypeus lighter, brown, labrum testaceous; pronotum light brown to testaceous; elytra dark brown to dark reddish brown; legs and maxillary palpi testaceous, tip of palpus not darker.

Frons punctures ca. 1xef, very slightly, if at all, larger and denser near eyes than medially; interstices shining, 1–3xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 7/1/5/5. P1 ca. 4/7 P2; median carina anterior to coxae, straight in profile; intercoxal process wide, medially concave. P2 transversely concave, l/w ca. 5/7, sides slightly diverging toward blunt apex. Plaques very narrow, carinate, converging slightly anteriorly, at sides of deep median depression. Metaventrite concave between P2 and plaques. AIS width at straight posterior margin ca. equal P2. All legs moderately long and slender. Profemur (male) without tubercle next to trochanter; protibia slightly arcuate, anterior margin slightly widened subapically. Meso- and metatibia straight. Abdominal apex symmetrical; last tergite (male) deeply notched. Pronotum very transverse, ca. median 3/4 of anterior margin arcuate to posterior; punctures on disc ca. 1xpd frons punctures, interstices shining, 1–3xpd, punctures very slightly, if at all, larger and denser at anterior and posterior; PF1 absent; PF2 very shallow, obsolete; PF3 shallow; PF4 absent.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins rather wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming shallow angle with one another. Aedeagus as illustrated ( Fig. 216).

Etymology. "Muscular, bulging"; named in reference to the thick cuticle between the pro- and mesocoxae.

Distribution. Currently known only from the type locality, Keki, in the Adelbert Mts., in the northwestern part of Area 5; elevation 400 m ( Fig. 532 ).

Figures

FIGURE 211. Hydraena tritropis, holotype, dorsal and lateral habitus, and venter.

FIGURE 214. Hydraena torosopala, holotype, dorsal and lateral habitus, and venter.

FIGURES 531–534. Geographical distributions of Hydraena species.

FIGURES 212–213. Aedeagi of holotypes. 212. H. formosopala. 213. H. tritropis.