Hydraena parva Zwick, 1977

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 : 77-78

Hydraena parva Zwick, 1977

(Figs. 122, 125–128, 252)

Hydraena parva Zwick, 1977: 172 .

Type Material. Holotype (male): Queensland, Charters Towers [labels: Ch. Towers, Q. 3-2-36 A. A. Ross // T. 7225. // Hydraena parva sp. n. det. P. Zwick Holotypus // Aedeagus drawn by P. D. Perkins // DIGITAL IMAGE captured 2004 P. D. Perkins]. Deposited in the QMBA.

Differential Diagnosis. Among species of the parva subgroup , most similar in size, body proportions, dorsal punctation, and plaque configuration to H. ambiosina ; differing therefrom by the more distinctively depressed sublateral area of the elytra, and the stronger sublateral ridge (Figs. 122, 125, 133). Examination of the quite distinct male genitalia will be necessary for reliable determinations (Figs. 126–128, 132).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.25/0.54; head 0.14/ 0.32; pronotum 0.31/0.42, PA 0.35, PB 0.39; elytra 0.76/0.54. Dorsum brown, margins of pronotum, legs and palpi lighter, head darker.

Frons punctures ca. 1xef; interstices shining, 1–2xpd. Clypeus microreticulate laterally, finely sparsely punctate medially. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge.

Pronotal punctures on disc slightly larger than those of frons, interstices shining, 1–3xpd, punctures denser at anterior, ca. 1xpd of discal punctures; PF1 absent or very shallow; PF2 very small and very shallow; PF3 moderately deep; PF4 absent.

Elytral punctures about equal size of largest pronotal punctures. Intervals not raised, shining, width about 1xpd, as are interstices between punctures of a row. Each elytron with sublateral depression, bordered laterally by rounded ridge. Apices in dorsal aspect truncate, in posterior aspect margins form moderately strong angle with one another.

Plaque/intercoxal process ratios (P2/w/l/s) 2/1/4/4. P1 almost laminate; median carina posterior extreme not more elevated than remainder. P2 narrow, l/w ca. 2/1, sides parallel, apex blunt. Plaques narrow, straight, located in posterior 1/2 of metaventrite on sides of shallow median depression. AIS flat, width at arcuate posterior margin 2x P2. All legs simple, tibiae slender. Last tergite produced in tiny point on each side of deep apicomedian notch.

Aedeagus (Figs. 126–128) main-piece wide, rather flat, widened on right side concealing paramere base, with very small process distally on right side; basal orifice nearly symmetrical in ventral view; distal piece comparatively simple, gonopore bearing flagellum short, terminal; parameres inserting at same level; left paramere very slender, setae apical; right paramere sinuate in ventral view, markedly tapering to fine tip in lateral view, about four or five setae clustered on ventral margin near midlength. Female last tergite with three incisions, delimiting four lobes, setae slender, tapering.

Distribution. Widely, but very sparsely, distributed in the northern areas of Western Australia, Northern Territory, and Queensland (Fig. 252).

Material Examined (28): Northern Territory, Elsey Creek, 19 km SSE Mataranka, 15° 5' S, 133° 7' E, 14 May 1973, M. S. Upton (6 ANIC); Jim Jim Falls Camp. Area, elev. 60 m, 13° 16' S, 132° 49' E, 26–27 November 1996, L. Hendrich (2) (1 NMW); Kakadu N. P., Gungurul Lookout, creek, elev. 50 m, 13° 59' S, 132° 19' E, 1 November 1996, L. Hendrich (1 NMW); Kakadu N. P., Jim Jim Hwy., Barramundi Creek , elev. 30 m, 12° 59' S, 132° 22' E, 30 October 1996, L. Hendrich (8) (1 NMW); Keep River Gorge, Keep River Nat. Pk., deep billabong with rocks and floating leaves, etc., 15° 50' S, 129° 7' E, 22 July 1994, T . Weir & A. Roach (1 ANIC); McArthur River , 80 km SW of Borroloola, 16° 39' S, 135° 51' E, 13 May 1973, M. S. Upton (4 ANIC) ; Queensland, 6 km W Dimbulah , 17° 8' S, 145° 6' E, 10 November 1990, D. Larson (1 MCZ) ; Western Australia, 14 km SbyE Kalumburu Mission, CALM Site 4/3 [Western Australian Department of Conservation and Land Management], at light, closed forest, 14° 25' S, 126° 40' E, 3–6 June 1988, T . A. Weir (1 ANIC); 14 km SbyE Kalumburu Mission, CALM Site 4/3 [Western Australian Department of Conservation and Land Management], at light, open forest, 14° 25' S, 126° 40' E, 3–6 June 1988, T . A. Weir (6 ANIC); Synnot Ck., CALM Site 25/1 [Western Australian Department of Conservation and Land Management], at light, closed forest margin, 16° 31' S, 125° 16' E, 17–20 June 1988, T . A. Weir (6 ANIC) .