Hydraena cunicula, 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 : 66-67

Hydraena cunicula , new species

( Figs. 103 , 105, 478 )

Type Material. Holotype (male): Madang Province: Akameku–Brahmin , Bismarck Range, 250–500 m, 5° 47.026' S, 145° 24.131' E, 25 xi 2006, Balke & Kinibel ( PNG 115) ( ZSM) . Paratypes (2): Madang Province: Same data as holotype (1 ZSM); near Brahmin, 200 m, 5° 47.026' S, 145° 24.131' E, 25 xi 2006, Balke & Kinibel ( PNG 116) (1 ZSM) .

Differential Diagnosis. The pronotal shape and impressions are somewhat similar to those of H. velvetina (Velvetina group) and H. fasciata (Colorata group) ( Figs. 90 , 103 , 106 ). However, the overall body shape, metaventral plaque ratios, and legs of males differ from those of the compared groups. The aedeagus of H. cunicula ( Fig. 105) also indicates that placement should not be with those groups.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.59; head 0.21/0.33; pronotum 0.32/0.44, PA 0.36, PB 0.35; elytra 0.79/0.59. Dorsum of head dark brown to piceous; labrum testaceous; pronotum light brown to testaceous in front of and behind brown to dark brown fascia, ratios of color bands, as measured in midline, ca. 6/11/4; elytra dark brown; legs light brown; maxillary palpi testaceous, tip not darker. Dorsum weakly shining.

Frons punctures ca. 1–2xef near eyes, smaller and sparser medially; interstices shining, medially 1–3xpd. Clypeus effacedly microreticulate laterally, very finely sparsely punctulate and shining medially. Mentum very sparsely very finely punctulate, strongly shining. Postmentum effacedly microreticulate in posterior 1/2, otherwise finely sparsely punctulate. Genae very slightly raised, shining, without posterior ridge, but lateral impressions wide. Pronotum cordiform, median 2/3 of anterior margin emarginate; sides straight or very slightly emarginate between anterior angle and widest part, sinuate between widest part and posterior angle; punctures on disc ca. 1xpd largest frons punctures, interstices shining, ca. 1–3xpd, punctures anteriorly and posteriorly denser than those on disc; PF1 and PF4 very shallow; PF2 moderately deep, medially conjointly shallowly confluent; PF3 moderately deep, wide.

Elytra transversely convex, 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 largest pronotal punctures, a few punctures subserial, punctures becoming gradually smaller toward posterior. Intervals not raised, very weakly shining, on disc ca. 1–2xpd, 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. 4/1/5/4. P1 slightly wider than laminate; median carina sinuate in profile, slightly raised between coxae. P2 wide, length/width ca. 5/4, sides very slightly diverging toward blunt apex. Plaques very narrow, raised but not carinate, at sides of deep median inverted V-shaped depression, anteriorly slightly convergent. Metaventrite slightly concave between mesocoxae. AIS width at straight posterior margin slightly greater than P2. All legs of moderate length, slender. Profemur (male) with minute tubercle on ventral margin near trochanter; protibia slightly arcuate, gradually increasing in width from base to apex. Meso- and metatibia straight, slender. Metatibia widest, but extremely slightly so, near midlength. Abdominal apex symmetrical; last tergite (male) with deep apicomedian notch. Aedeagus as illustrated ( Fig. 105).

Etymology. "Little rabbit"; named in reference to the rabbit ear shape of the aedeagus.

Distribution. Currently known only from two very closely spaced localities in eastern Area 3; elevation range 200–500 m ( Fig. 478 ).

Figures

FIGURE 90. Hydraena fasciata, holotype, dorsal and lateral habitus, and venter.

FIGURE 103. Hydraena cunicula, holotype, dorsal and lateral habitus, and venter.

FIGURE 106. Hydraena velvetina, holotype, dorsal and lateral habitus, and venter.

FIGURES 475–478. Geographical distributions of Hydraena species.