Hydraena weiri, 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 : 48

Hydraena weiri new species

(Figs. 67, 79, 257)

Type Material. Holotype (male): Western Australia, 14 km S by E Kalumburu Mission, CALM Site 4/3 [Western Australian Department of Conservation and Land Management], 14° 25' S, 126° 40' E, at light, closed forest, 3–6 June 1988, T. A. Weir. Deposited in the ANIC . Paratypes: Western Australia, Synnot Ck., CALM Site 25/1 [Western Australian Department of Conservation and Land Management], 16° 31' S, 125° 16' E, at light, closed forest margin, 17–20 June 1988, T . A. Weir (4 ANIC) .

Differential Diagnosis. Recognized from all species, except H. arcta and H. tenuisella , by the very flat, narrow, parallel-side form (Figs. 67, 74, 75). H. weiri is larger than H. arcta , and smaller than H. tenuisella , and the microreticulation of the frons and clypeus is weaker in H. weiri ; however, these species are otherwise very similar in dorsal sculpture and plaque proportions; reliably distinguishing among the three species will require examination of the aedeagi (Figs. 78–80).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 1.25/0.49; head 0.20/ 0.33; pronotum 0.31/0.39, PA 0.33, PB 0.34; elytra 0.74/0.49. Head dark brown to piceous; pronotum dark brown, anterior angles slightly lighter; elytra dark brown; legs and palpi light brown to testaceous, tip of last palpomere not darker.

Frons punctures less than 1xef; interstices shining, 2–5xpd. Clypeus microreticulate laterally, finely sparsely punctate and shining medially. Mentum weakly shining, very finely sparsely punctate; postmentum microreticulate. Genae weakly raised, lacking posterior ridge. Pronotum finely sparsely punctate; punctures on disc ca. 1xpd those of frons, interstices strongly shining, 2–5xpd, largest on disc; PF1, PF2 and PF4 absent; PF3 very shallow, broad.

Elytral punctures ca. 1xpd of smallest pronotal punctures. Intervals not raised, strongly shining, width about 2–3xpd, as are interstices between punctures of a row. Elytra parallel-sided or nearly so. Apices in dorsal aspect truncate, in posterior aspect margins form marked angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/2/7/2. P1 laminate; median carina weakly angulate in profile. P2 l/w ca. 5/2, sides parallel or weakly diverging, apex blunt. Plaques large, slightly raised, located in posterior 3/5 of metaventrite on sides of shallow median depression; plaques straight, parallel or nearly so, very weakly tapering anteriorly. AIS flat, width at arcuate posterior margin ca. 1.5x P2. Legs simple. Last tergite cap-like, asymmetrical.

Aedeagus (Fig. 79) main-piece with very large basal orifice, narrow process distally on right side that angles toward left; distal piece with large lobes, process that terminates in gonopore-bearing flagellum angled toward left side; both parameres inserting at same level, near base of main-piece; left paramere very narrow, slightly longer than right, with about eight setae on ventral surface apically; right paramere enlarged basally, arcuate, very sharply pointed, with about four long setae on ventral surface near midlength. Female last tergite with very faint apicomedian emargination, or none, setae slender, tapering.

Etymology. Named in honor of the collector, Thomas Weir.

Distribution. Currently known from northeastern Western Australia (Fig. 257).