Hydraena mercuriala, 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 : 78-79

Hydraena mercuriala , new species

( Figs. 130 , 132, 404 , 491 )

Type Material. Holotype (male): Sandaun Province: May River , ex river side pool, 970 m, 4° 49.779' S, 141° 38.174' E, 19 x 2003, K. Sagata (WB 41) ( ZSM) . Paratypes (62): Eastern Highlands Province: Akameku– Brahmin , Bismarck Range, 700 m, 5° 52.754' S, 145° 23.209' E, 24 xi 2006, Balke & Kinibel ( PNG 109) (2 ZSM) ; Madang Province: Simbai area , 1200 m, 5° 13.389' S, 144° 37.285' E, 10 iii 2007, Kinibel ( PNG 152) (16 MCZ, NHM, NMW, PNG, ZSM) ; Sandaun Province: Same data as holotype (2 ZSM) ; Mianmin , 670 m, 4° 53.292' S, 141° 34.118' E, 20 x 2008, S. Ibalim ( PNG 191) (2 ZSM) ; same locality, 22 x 2008, S. Ibalim ( PNG 189) (1 ZSM) ; Mianmin , pool, 990 m, 4° 54.57' S, 141° 35.49' E, 23 x 2008, S. Ibalim ( PNG 193) (4 ZSM) ; Mianmin , river, 700 m, 4° 52.858' S, 141° 31.706' E, 21 x 2008, S. Ibalim ( PNG 197) (8 MCZ, NHM, NMW, PNG, ZSM) ; Mianmin , river, 1080 m, 4° 55.78' S, 141° 38.185' E, 24 x 2008, S. Ibalim ( PNG 195) (15 MCZ, NHM, NMW, PNG, ZSM) ; Ofektamin , 820 m, 5° 4.113' S, 141° 35.841' E, 17 x 2008, S. Ibalim ( PNG 190) (12 MCZ, NHM, NMW, PNG, ZSM) .

Differential Diagnosis. Very similar in external characters to H. ollopa ( Figs. 130 , 131 ). Reliable determinations will require examination of the distinctively different male genitalia ( Figs. 132, 133).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.92/0.80; head 0.29/0.43; pronotum 0.44/0.52, PA 0.44, PB 0.43; elytra 1.14/0.80. Dorsum piceous; legs brown; maxillary palpi brown except distal 1/2 of last palpomere darker.

Frons moderately coarsely, moderately densely punctate, punctures ca. 1–2xef; interstices shining, 0.5–5xpd, punctures smallest and sparser on disc. Clypeus microreticulate laterally, finely, sparsely punctate medially. Mentum very sparsely very finely punctulate, strongly shining, each puncture with moderately long recumbent seta; postmentum medially micropunctulate in small subtriangular area, otherwise finely sparsely punctate, shining. Genae raised, shining, without posterior ridge. Pronotum cordiform, median 2/3 of anterior margin emarginate; punctures on disc ca. 1xpd largest punctures of frons, interstices shining, 1–2xpd, punctures slightly larger and denser at posterior; PF1 very shallow; PF2 moderately deep, very shallowly confluent; PF3 deep; PF4 moderately deep.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate 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. 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. 4/2/10/7. P1 laminate; median carina sinuate in profile. P2 raised, l/w ca. 3/2, sides slightly converging toward apex. Plaques moderately wide, flat, converging slightly from posterior to anterior, located at sides of deep median depression. Metaventrite without midlongitudinal ridge. AIS width at straight posterior margin ca. 1.5x P2. All legs long and slender. Profemur (male) without tubercle near trochanter; protibia straight. Mesotibia slightly arcuate, medial surface widened and with small tubercle subapically. Metatibia moderately arcuate in distal 1/2; metatarsus with large brush of setae on ventral surface of basal tarsomeres. Abdominal apex slightly asymmetrical; last tergite (male) deeply notched. Aedeagus ( Fig. 132) with large lobe on ventral face of main piece; distal piece very complicated, with cluster of large, strongly sclerotized spines on left side. Female tergite X, gonocoxite, and spermatheca as illustrated ( Fig. 404 ).

Etymology. Named in reference to the mythological Mercury, who had wings on his heels; males have a large setal brush on the hind tarsi.

Distribution. Appears to track Area 2 rather well; found at several localities in the Mianmin area (670–1080 m) and two sites in eastern Area 2 (1200 m and 700 m) ( Fig. 491 ).

Figures

FIGURE 130. Hydraena mercuriala, holotype, dorsal and lateral habitus, and venter.

FIGURE 131. Hydraena ollopa, holotype, dorsal and lateral habitus, and venter.

FIGURES 404–407. Female tergite X, gonocoxite, and spermatheca of Hydraena species.

FIGURES 491–494. Geographical distributions of Hydraena species.