Hydraena revelovela, 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 : 46

Hydraena revelovela new species

(Figs. 68, 71, 260)

Type Material. Holotype (male): Northern Territory, Kakadu N. P., Gungurul Lookout , creek, elev. 50 m, 13° 59' S, 132° 19' E, 1 November 1996, L. Hendrich. Deposited in the SAMA . Paratypes: Same data as holotype (3 NMW) .

Differential Diagnosis. Distinguished from other members of the bidefensa Group by the small size (ca. 1.17 mm) and the distinctive, narrow, dark brown fascia across the otherwise testaceous pronotum (Fig. 68). The pronotal punctures are much coarser than the elytral punctures, and the plaques are narrow, widely separated, carinate lines. The aedeagal form (Fig. 71) also distinctively differs from that of the other bidefensa Group species.

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.17/0.49; head 0.19/ 0.28; pronotum 0.31/0.38, PA 0.31, PB 0.34; elytra 0.70/0.49. Head dark brown except lateral margins of clypeus and adjacent areas of frons light brown; pronotum with dark brown fascia over testaceous anterior and posterior areas; elytra dark brown; legs and palpi light brown to testaceous, tip of palpi not darker.

Frons microreticulate except on disc, punctures ca. 1xef; interstices shining on disc, 2–3xpd. Clypeus microreticulate. Mentum shining, finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotum shining on disc, effacedly microreticulate and dull laterally; punctures on disc ca. 2xpd those of frons, interstices shining, anteriorly and posteriorly 1–2xpd, on disc 2–4xpd; PF1 absent; PF2 very shallow; PF3 moderately deep; PF4 shallow.

Elytral punctures very small and shallow, much smaller than largest pronotal punctures, becoming widely separated and subserial or random over posterior declivity. Intervals not raised, weakly shining, width on disc about 3–4xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins form very moderately strong angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/0.5/5/5. P1 laminate; median carina angulate in profile. P2 moderately narrow, l/w ca. 2/1, sides parallel, apex blunt. Plaques carinate, weakly arcuate, widely separated both anteriorly and posteriorly, located in posterior 1/2 of metaventrite on sides of deep median depression. AIS flat, width at arcuate posterior margin 2x P2. Legs simple. Last sternite with very small, slightly off-center, produced margin; last tergite with deep, asymmetrical notch.

Aedeagus (Fig. 71) main-piece with long, sharply pointed process on right side; distal piece with small process on right side, gonopore bearing flagellum very short; left paramere shorter and wider than right, lobeshaped apically, positioned on ventral surface, setae in two groups; right paramere slender, bent near midlength, apex adjacent to apex of sharp process of main-piece, setae in one group at weakly widened apex. Female last tergite with very small, almost imperceptible, apicomedian incision, setae slender, tapering.

Etymology. "Reveal hiding"; named in reference to the distinctively banded dorsal color pattern, possibly serving as disruptive coloration.

Distribution. Currently known only from the type locality in Kakadu National Park, northern Northern Territory (Fig. 260).