Hydraena torricellica, 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 : 140

Hydraena torricellica , new species

( Figs. 259 , 261 , 554 )

Type Material. Holotype (male): Morobe Province: Torricelli Mts. , village below Sibilanga Stn., 400 m, 3° 26.75' S, 142° 29.949' E, 18 iv 2006, Balke ( PNG 42) ( ZSM) . Paratype: Same data as holotype (1 female ZSM) .

Differential Diagnosis. Differentiated from other members of the Fundarca group by the testaceous pronotum, which has the anterior margin very weakly produced in the middle ( Fig. 259 ). The form of the aedeagus and the shape of the male abdominal apex clearly suggest that this species is allied with the putative sister species pair H. fundacta and H. johncoltranei . In addition to the testaceous pronotum, H. torricellica differs from the compared species by the carinate metaventral plaques, and the transversely concave intercoxal process of the metaventrite. The male genitalia of the three species distinctively differ in many details ( Figs. 261 , 264, 265 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.45/0.63; head 0.24/0.35; pronotum 0.38/0.50, PA 0.38, PB 0.48; elytra 0.87/0.63. Dorsum of head with frons dark brown to piceous, clypeus brown, labrum testaceous; pronotum testaceous; elytra dark brown; legs light brown; maxillary palpi testaceous, tip not darker. Dorsum moderately shining.

Frons punctures ca. 1xef near eyes, much smaller and much sparser medially; interstices shining, 1–6xpd. Clypeus effacedly microreticulate laterally, very finely sparsely punctulate and shining medially. Mentum very sparsely very finely punctulate, shining. Postmentum effacedly microreticulate in shallow median depression, otherwise finely sparsely punctate. Genae very slightly raised, shining, with shallow, obsolete median impression, without posterior ridge. Pronotum transverse, anterior margin very weakly bisinuate, very weakly produced in middle, sides weakly arcuate, slightly emarginate between midlength and posterior angle; punctures on disc ca. 1xpd largest frons punctures, interstices shining, ca. 2–4xpd, punctures anteriorly and posteriorly slightly larger than those on disc; PF1, PF2 and PF4 absent; PF3 shallow, wide.

Elytra widest at about midlength; summit of posterior declivity at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd of 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.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 6/1/3/8. P1 laminate; median carina nearly straight in profile, very slightly arcuate between coxae. P2 markedly concave, length/width ca. equal, sides very slightly diverging toward blunt, slightly concave apex. Plaques very short, widely separated, carinate lines, converging anteriorly, at sides of median depression. Metaventrite between mesocoxae slightly sloping, transversely concave, confluent with tip of P2. AIS width at straight posterior margin ca. equal P2. All legs of moderate length. Profemur (male) without tubercle on ventral margin near basal 1/3; protibia straight, posteromedial margin very slightly widened to form narrow ridge at about midlength, medial margin weakly concave. Meso- and metatibia straight, slender. Abdominal apex (male) enlarged, asymmetrical; last tergite with oblique ridge on dorsal surface. Aedeagus as illustrated ( Fig. 261 ).

Etymology. Named in reference to the geographical distribution.

Distribution. Currently known only from the type locality in the Torricelli Mts.; this is in Area 4, elevation 400 m ( Fig. 554 ).

Figures

FIGURE 259. Hydraena torricellica, holotype, dorsal and lateral habitus, and venter.

FIGURES 260–261. Aedeagi of holotypes. 260. H. photogenica. 261. H. torricellica.

FIGURES 551–554. Geographical distributions of Hydraena species.

FIGURES 264–265. Aedeagi of holotypes. 264. H. fundacta. 265. H. johncoltranei.