Oecetis radonensis sp. nov.

Figures 16, 17, 61

Material examined. Holotype. Male, NT, Kakadu National Park, Radon Springs, Suter and Wells, 13–14 Apr 1989 (NMV T-18840).

Paratypes. NT: 17 males, 14 females, same data as for holotype (NMV and NTM: 1 male on slide); 4 males, 3 females, Little Baroalba Creek, 25–26 Apr 1991, Wells and Webber (ANIC) ; 1 male, Kakadu National Park, Baroalba Springs, 12°48'S, 132°49'E, 4 Mar 1992, Wells (NTM) .

Other material. NT: 1 male, Radon Creek, Kakadu National Park, 3 Sep 1979, J. Blyth (NMV). WA: 1 male, Mitchell Plateau, 30 Jan 1978, J.E. Bishop (NMV) .

Diagnosis. Closely similar to O. humphreyi sp. nov. but male distinguished by having inferior appendages in ventral view, stout throughout length, rounded apically, and with 2 small patches of setae at about two-thirds length; phallus longer with paramere only very slightly curved.

Description. Male. Wings narrow, dark markings at crossveins, anastomoses and at marginal ends of veins; vestiture short; with a single elongate patch of scales; forewing length 4.8–5.5 mm. Abdominal segments III and IV with tergites sclerotised; segment IX excavated mid-ventrally and thus appearing to have well-developed lateral lobes; X spatulate in dorsal view, slender and elongate in lateral view. Genitalia, see figs 16, 17. Pre-anal appendages sub-triangular. Phallus about 1.5 segments long; phallotheca with membranous apex sharply down-turned; paramere in lateral view slightly curved. Inferior appendages elongate and in ventral and lateral views almost uniformly stout throughout length; in ventral view with apices in-turned, without a basi-dorsal pouch; dorsally at about two-thirds length a small group of short setae on a raised papilla, another cluster on mesial margin, these possibly homologous with the sets of setae on papillae in the basi-dorsal pouches seen in O. pechana and other species.

Distribution. From the Kimberley region of northern WA and the north of the NT, but not a commonly collected species.

Etymology. Named for the type locality, on the edge of Mt Brockman in Kakadu National Park.