Hydraena huonica, 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 : 52

Hydraena huonica , new species

( Figs. 71 , 73 , 467 )

Type Material. Holotype (male): Madang Province: Kewensa, Finisterre Range, Yupna , Huon Peninsula , stream margin, [GE est.] 100–500 m, 5° 49' S, 146° 46' E, 1–30 vii 1975, R. W. Hornabrook ( NMNZ) . Paratypes: Same data as holotype (12 NMNZ) .

Differential Diagnosis. Similar to H. tarsotricha in habitus and male sexual dimorphisms (no tubercle on first abdominal ventrite, fifth ventrite with transverse ridge, meso- and metatarsi with long hair-like setae) ( Figs. 67 , 71 ); differing therefrom by the narrower mesoventral intercoxal process P2 (ratios ca 2/4/13/1 vs. 3/4/13/1). The male genitalia are also quite similar, differing most notably in the shapes of the parameres, and in details of the distal piece; reliable determinations will require examination of the aedeagi ( Figs. 69, 73 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.73/0.70; head 0.28/0.40; pronotum 0.41/0.49, PA 0.43, PB 0.43; elytra 1.07/0.70. Dorsum piceous; legs and maxillary palpi dark brown.

Frons punctures ca. 1–1.5xef, slightly larger near eyes than medially; interstices shining, 1–5xpd. Clypeus microreticulate laterally, very finely sparsely punctate medially. Mentum very sparsely very finely punctulate, shining; postmentum densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Pronotum cordiform, median 2/3 of anterior margin emarginate; punctures on disc ca. 1xpd those of frons, interstices shining, 2– 4xpd, punctures slightly larger and denser at anterior and posterior; PF1 absent; PF2 very shallow, obsolete; PF3 deep; PF4 absent.

Elytra with summit of posterior declivity slightly past midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, shining, on disc ca. 1–2xpd, as are interstices between punctures of a row, a few punctures subserial. Apices in dorsal aspect separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/4/13/1. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 3/1, sides converging toward blunt apex. Plaques very large, very narrowly separated, slightly more narrowly separated posteriorly than anteriorly, weakly raised, slightly slanting toward midline. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 2x P2. All legs long and very slender. Profemur (male) with small, sharply pointed tubercle next to trochanter; protibia straight or very slightly arcuate, distal 1/3 widened on anterior surface, cluster of short spines on medial surface at apex, moderately long spine on medial surface at base of widened area. Mesotibia very slightly arcuate. Metatibia straight, medial margin in distal 1/2 very slightly emarginate. Meso- and metatarsi with long hair-like setae along lower margin of basal tarsomeres. Fifth abdominal ventrite posteriorly transversely raised. Abdominal apex symmetrical; last tergite (male) deeply notched. Aedeagus as illustrated ( Fig. 73 ).

Etymology. Named in reference to the Huon Peninsula.

Distribution. Currently known only from the type locality on the Huon Peninsula (Area 5); elevation estimated at 100–500 m ( Fig. 467 ).

Figures

FIGURE 67. Hydraena tarsotricha, holotype, dorsal and lateral habitus, and venter.

FIGURE 71. Hydraena huonica, holotype, dorsal and lateral habitus, and venter.

FIGURES 72–73. Aedeagi of holotypes. 72. H. tricosipes. 73. H. huonica.

FIGURES 467–470. Geographical distributions of Hydraena species.