Hydraena zwicki, 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 : 103-104

Hydraena zwicki new species

( Figs. 10 , 174, 222, 253)

Type Material. Holotype (male): Queensland, Clacherty Road, via Julatten , 16° 37' S, 145° 21' E, 8 January–2 February 1987, R. Storey & H. Howden. Deposited in the ANIC . Paratypes (38): Queensland, Same data as holotype (1 ANIC); Julatten , flight intercept trap, 16° 37' S, 145° 21' E, 26 December 1986 – 8 January 1987, H. Howden & R . Storey (2 ANIC); SW of Tully, pools below Murray Falls , 18° 9' S, 145° 49' E, 23 March 1992, H. & P. Zwick (35 PZC) .

Differential Diagnosis. Similar to H. triloba in color, dorsal sculpture, and plaques; differing therefrom by the slightly smaller size (ca. 1.31 vs. 1.40 mm), the less elongate elytra, and the more closely spaced elytra punctures (Figs. 174, 175). The aedeagi of the two species distinctively differ ( Figs. 10 , 172).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.31/0.59; head 0.21/ 0.35; pronotum 0.34/0.47, PA 0.38, PB 0.42; elytra 0.79/0.59. Head dark brown; pronotum with dark brown macula surrounded anteriorly and posteriorly by testaceous, middle 1/3 of length, between macula and lateral margin, of intermediate color; elytra dark brown; legs and palpi testaceous, tip of palpi not darker.

Frons effacedly microreticulate laterally, non-microreticulate and shining on disc, punctures less than 1xef; interstices 2–6xpd. Clypeus microreticulate laterally, finely sparsely punctate medially. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc only slightly larger than those on frons, each with moderately long, fine, recumbent seta, interstices shining, ca. 2–6xpd; punctures larger anteriorly and posteriorly, ca. 2xpd of discal punctures, interstices ca. 2–3xpd; PF1 and PF4 absent; PF2 very shallow, almost absent; PF3 shallow, broad.

Elytral punctures on disc slightly smaller than largest pronotal punctures, becoming finer over posterior declivity. Intervals not raised, shining, width about 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins form moderately strong angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/2/7/3. P1 laminate; median carina angulate in profile. P2 l/w ca. 2/1, sides parallel or weakly convergent, apex blunt. Plaques located in posterior 1/2 of metaventrite on sides of deep median triangular depression, slightly raised, tapering anteriorly, almost confluent at anterior extreme. AIS flat, width at arcuate posterior margin ca. 2x P2. Protibia (male) slightly arcuate, distal 1/2 slightly thickened; mesotibia slender; metatibia slender, very weakly emarginate on median surface over distal 3/4. Last sternite with small off-center lobe; last tergite with deep, off-center notch, located opposite sternite lobe.

Aedeagus ( Fig. 10 ) main-piece markedly angulate in ventral view, with two processes, one short near base and one very long on right side at angulation; distal piece as long as main-piece, with (in lateral view) two large, ovoid, rather flat processes, gonopore-bearing flagellum short, at end of long, tubular process; parameres inserting at same level on main-piece; left paramere much narrower than right, tapering to fine tip, short setae in row along ventral margin; right paramere very wide, setae in three groups, two groups on ventral margin, and one group apically. Female last tergite subtriangular, with three incisions delimiting lobes, medial pair of lobes much larger than lateral pair, setae slender, tapering; subapical, median process, at base of which issue long setae that join together at their tips, forming a "pencil" in dry specimens; gonocoxite as illustrated (Fig. 222).

Etymology. Named in honor of Peter Zwick, in recognition of his diverse contributions to aquatic Entomology.

Distribution. Currently known from northeastern Queensland (Fig. 253).

Figures

FIGURES 9–10. Aedeagi of holotypes. —9. H. reticulositis. —10. H. zwicki.