Hydraena disparamera, 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 : 105-106

Hydraena disparamera new species

(Figs. 171, 176, 239)

Type Material. Holotype (male): Queensland, Cape Hillsborough, elev. 20 m, 20° 55' S, 149° 3' E, open forest, sieved litter, Q. M. berlesate no. 27, 16 April 1979, G. B. Monteith. Deposited in the QMBA.

Differential Diagnosis. Similar to H. triloba in color pattern and plaque proportions (Figs. 175, 176); differing therefrom in the narrower body form, the greater body length (ca. 1.49 vs. 1.40 mm), the slightly more densely punctate dorsum, and, in males, the differently shaped metatibiae. The aedeagi of the two species markedly differ (Figs. 171, 172).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.49/0.58; head 0.24/ 0.35; pronotum 0..36/0.44, PA 0.38, PB 0.42; elytra 0.90/0.58. Dorsum light brown to testaceous (holotype is slightly teneral); 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 ca. 2xpd those on frons, interstices shining, ca. 2–4xpd; punctures slightly smaller anteriorly, and slightly larger 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 equal to or slightly smaller than largest pronotal punctures, becoming finer posteriorly. Intervals not raised, shining, width about 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect weakly, separately rounded, in posterior aspect margins form moderately strong angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 4/5/14/4. P1 laminate; median carina angulate in profile. P2 l/w ca. 2/1, sides parallel or weakly convergent, apex blunt. Plaques large, distinctively roundly raised, converging slightly and tapering slightly toward anterior; width of groove separating plaques slightly less than plaque width. AIS flat, width at arcuate posterior margin ca. 2x P2. Protibia (male) gradually weakly widened to about distal 2/3, then tapering to apex; mesotibia slender; metatibia slender, emarginate and flattened on inner surface over middle 1/3 of length, lower margin sharp between emargination and apex. Last sternite symmetrical or nearly so; last tergite with deep, off-center concavity.

Aedeagus (Fig. 171) main-piece with lobe on ventral surface and with large distal lobe extending from right to left side; distal piece widest in lateral view, with several lobes, terminating in short gonopore-bearing flagellum; left paramere large, ventral margin with angulate lobe at proximal 1/3, distal 1/2 tapering, with only a few minute setae on ventral margin; right paramere also very asymmetrical, with unusual shape and setae (see figure). Females not yet known.

Etymology. Named in reference to the unusual and very dissimilar aedeagal parameres.

Distribution. Currently known only from the type locality, Cape Hillsborough, near the coast in central Queensland (Fig. 239).