Hydraena metzeni, Published, 2007

PERKINS, PHILIP D., 2007, A revision of the Australian species of the water beetle genus Hydraena Kugelann (Coleoptera: Hydraenidae), Zootaxa 1489 (1), pp. 1-207 : 119

Hydraena metzeni new species

(Figs. 204, 207, 225, 257)

Type Material. Holotype (male): Queensland, 15 km NE Mareeba , MDPI intercept trap site No. 25, flight intercept trap, elev. 400 m, 16° 56' S, 145° 32' E, 7 January–12 February 1985, Storey & Halfpapp. Deposited in the QMBA ). Paratypes (46): Northern Territory, Kakadu N. P., Gungurul Lookout , creek, elev. 50 m, 13° 59' S, 132° 19' E, 1 November 1996, L. Hendrich (41 NMW) ; Kakadu N. P., Nawurlandja , 12° 49' S, 132° 51' E, 18 March 1998, C. Watts (1 SAMA) ; Queensland, Mareeba , elev. 700 m, 16° 59' S, 145° 25' E, 22 January 1993, Wewalka (18) (3 NMW) ; Normanby River , water sweep, 15° 18' S, 144° 51' E, 27 June 1993, P. Zborowski & I. Naumann (1 ANIC) .

Differential Diagnosis. Externally similar in some characters to H. fundata ; differing therefrom by the larger size (ca. 1.61 vs. 1.40 mm), the fasciate instead of maculate pronotum, the weakly emarginate sides of the pronotum, the broader elytra, and the more truncate elytral apices (Figs. 193, 204). The male genitalia of the two species are very dissimilar (Figs. 201, 207).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.61/0.72; head 0.24/ 0.38; pronotum 0.42/0.56, PA 0.44, PB 0.56; elytra 0.97/0.72. Head dark brown to piceous; pronotum with large dark brown to piceous fascia, bordered narrowly anteriorly and posteriorly by testaceous; elytra dark brown; maxillary palpi and legs testaceous. Dorsum strongly shining.

Frons punctures near eyes ca. 1xef, much finer and very sparse on disc. Clypeus very finely sparsely punctate on disc, very weakly, effacedly microreticulate laterally. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotum very finely, very sparsely punctate; PF1, PF2 and PF4 absent; PF3 shallow, broad.

Elytral punctures very fine and very sparse, becoming obsolete over posterior declivity. Intervals not raised, strongly shining. Apices in dorsal aspect conjointy truncate, in posterior aspect margins form strong arc with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 3/2/8/4. P1 laminate; median carina weakly sinuate in profile. P2 short, moderately wide, l/w ca. 3/3, sides slightly convergent, apex blunt. Plaques large, tapering anteriorly, convergent and nearly confluent anteriorly, located on sides of deep median triangular depression. AIS flat, width at arcuate posterior margin less than 2x P2. Legs simple; metatibia very slender, straight. Last sternite slightly asymmetrical, with very small apical lobe; last tergite nearly circular, positioned vertically and slightly within penultimate tergite, margin with slightly off-center, reflexed lobe, concave beneath.

Aedeagus (Fig. 207) twisted clockwise in relation to very large, asymmetrical basal opening, hence left paramere visible in lateral view but not ventral view; distal piece with long gonopore bearing flagellum that is angulate near base; right side of distal piece, in lateral view, with large, sail-shaped process that is behind left paramere; left paramere much longer than right, arcuate, with about six setae at apex; right paramere inserting only very slightly distal to insertion of left paramere, with setae at rounded, slightly widened, apex. Female last tergite with three incisions, delimiting four lobes, setae very long, slender, tapering; gonocoxite as illustrated (Fig. 225).

Etymology. Named in honor of Phillip L. Metzen, long-time friend and fellow sailing enthusiast.

Distribution. Currently known from northeastern Queensland and northern Northern Territory (Fig. 257).