Hydraena wattsi, 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 : 121

Hydraena wattsi , new species

(Figs. 206, 208, 250)

Type Material. Holotype (male): Northern Territory, Holmes Jungle , 11 km NE by E of Darwin, 12° 24' S, 130° 56' E, 24 March 1998, C. H. S. Watts. Deposited in the SAMA.

Differential Diagnosis. A very distinctive, flightless species, not easily compared to other Australian Hydraena ; recognized by the narrow and flat body form, the small eyes, and the coarse pronotal punctation. The elytral punctures are very coarse, appearing to form about five irregular rows on the disc, but with "extra" punctures (i.e., remnants of previous rows) here and there, punctures becoming random posteriorly (Fig. 206). The aedeagus is also very unique (Fig. 208).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.47/0.53; head 0.24/ 0.30; pronotum 0.34/0.42, PA 0.34, PB 0.34; elytra 0.90/0.53. Light brown to testaceous, head slightly darker. Eyes very small, facets fine; elytra fused (flightless); body form weakly convex.

Frons coarsely densely punctate; interstices shining on disc, ca. 0.5xpd, microreticulate at lateral extreme. Clypeus shining in midline, microreticulate laterally. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures coarse, deep, dense, interstices shining, 0.5–1xpd; PF1 and PF4 absent; PF2 shallow, oblique; PF3 moderately deep, broad.

Elytra with about five very irregular "rows" of punctures on disc, rows often with side-by-side puncture pairs, punctures becoming even more random laterally and posteriorly; punctures very coarse, slightly larger than largest pronotal punctures; interpunctal areas very weakly, if at all, raised, shining, width less than puncture diameter; apices in dorsal aspect conjointly rounded, in posterior aspect margins do not form angle with one another.

Plaque/intercoxal process ratios (P2/w/l/s) ca. 1/0.7/4/4. P1 laminate; median carina straight in profile. P2 narrow, l/w ca. 4/1, sides slightly convergent, apex blunt. Plaques narrow, straight lines, slightly raised, slightly convergent anteriorly, located at sides of shallow median depression. AIS flat, width at arcuate posterior margin ca. 2x P2. Protibia gradually increasing in width from base to apex, inner margin very weakly emarginate. Mesotibia and metatibia slender, simple. Last sternite symmetrical; last tergite with small apicomedian notch.

Aedeagus (Fig. 208) main-piece with elongate, arm-like process distally; distal piece with basal bifid fimbriate process, several lobes at midlength, and terminating in gonopore-bearing flagellum; left paramere very large, inserting near base and almost as long as aedeagus, ventral margin produced in small process, setae sparse, along ventral and dorsal margins; right paramere moderately large, inserting above left paramere, enlarge distally, setae in two groups. Females not yet known.

Etymology. Named in honor of the collector, Chris Watts.

Distribution. Currently known only from the type locality in northern Northern Territory (Fig. 250).