Hydraena larsoni, 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 : 99-100

Hydraena larsoni new species

(Figs. 166, 168, 254)

Type Material. Holotype (male): Queensland, Windsor Tablelands , 16° 13' S, 145° 2' E, roadside pond, 7 February 1991, D. Larson. Deposited in the QMBA . Paratypes: Queensland, Windsor Tablelands , Foxwood Stn., 16° 13' S, 145° 2' E, 6 February 1991, D. Larson (4 QMBA) .

Differential Diagnosis. Externally somewhat resembling H. inancala ; differing therefrom by the narrower body form, and the coarser pronotal punctation (Figs. 157, 168). The aedeagus shows some similarity, in the shape of the distal piece, to that of H. inancala , but the main-piece is very different, having a large,

markedly arcuate (nearly forming a circle) process and being, in that regard, more similar to the aedeagus of H. hamifera (Figs. 161, 166, 167).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.61/0.63; head 0.27/ 0.38; pronotum 0.38/0.52, PA 0.42, PB 0.44; elytra 0.98/0.63. Head dark brown to piceous; pronotum and elytra dark brown; legs brown; palpi light brown to testaceous, tip of last palpomere not darkened.

Frons punctures ca. 1xef; interstices weakly shining, 1–2xpd. Clypeus microreticulate. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures dense, 2–3xpd and deeper than those of frons, interstices shining, narrow walls forming reticulate patter; PF1 and PF4 absent; PF2 small, shallow; PF3 moderately deep, broad.

Elytral serial punctures very regular, about equal size of largest pronotal punctures; intervals not raised, shining, width less than puncture diameter, as are interstices between punctures of a row; apices in dorsal aspect conjointly rounded, in posterior aspect margins form shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/2/11/4. P1 laminate; median carina angulate in profile. P2 l/w ca. 5/2, sides parallel or slightly divergent, apex blunt. Plaques located in posterior 3/5 of metaventrite at margin of median triangular depression, plaques straight, very narrowly separated anteriorly, each plaque with lateral margin gradual, medial margin abrupt. AIS flat, width at arcuate posterior margin ca. 2x P2. Profemur (male) with minute tubercle near base. Protibia arcuate, slightly thickened in distal 1/2; mesotibia simple; metatibia slender, medial surface very weakly emarginate over distal 2/3. Last sternite with small apical lobe; last tergite emarginate.

Aedeagus (Fig. 166) main-piece with large, arm-shaped process on right side that almost forms a circle; base markedly asymmetrical; distal piece with two processes, gonopore on thin process angled toward left side, other process lobe-shaped and angled toward right side; left paramere about same length as right, angularly produced on ventral surface, setae in two groups; right paramere arcuate, setae in two groups. Female last tergite with three incisions, delimiting four lobes, setae slender, tapering.

Etymology. Named in honor of the collector and noted Dytiscidae specialist, David Larson.

Distribution. Currently known only from the Windsor Tablelands, northeastern Queensland (Fig. 254).