Key to the known australian gonocerini *

1. Costal margin of corium smooth, unserrated; space between each hind coxae 1 to 1.5 times diameter of one coxae; posteroventral edge of male genital capsule with prominent medial plate (Figs. 17–18); head pentagonal, elongate (Figs.10,15) ................................................................................... Plinachtus Stål ... 2

1’. Costal margin of corium crenulate to serrate; space between each hind coxae less than 0.7 times diameter of one coxae; posteroventral edge of male genital capsule without median plate (Fig. 20); head subquadrate, obliquely bent(Figs.11–14).................................................................................................................. 3

2. Humeral angle’s tapering into short acute spine (Fig. 3); antennal segment I somewhat triquetral; antennal segment III narrowly elliptical and expanded (Fig. 1); rostral segments I and II pale yellow, III and IV shiny orange; costal margin of corium with a pale yellow longitudinal stripe .................... P. melinus n. sp.

2’. Humeral angle’s projection remarkably large and acute (Fig. 4); antennal segment I not triquetral; antennal segment III cylindrical, not apically expanded (Fig. 2); rostral segment I yellow, II black with basal joint yellow, III–IV black; costal margin of corium without pale yellow longitudinal stripe ....................... ........................................................................................................................................... P. refulgens n. sp.

3. Posterior angles of connexival segments IV–V produced into short subacute projection; connexivum conspicuously raised above tergum; outer border of antenniferous tubercles always armed (Fig. 11)............... .................................................................................................................................. Cletomorpha Mayr ... 4

3’. Posterior angles of connexival segments obtuse, not produced; connexivum not conspicuously raised above tergum; outer border of antenniferous tubercles usually unarmed ..................................... Cletus Stål ..................................................................................................................................................................... 5

4. Total body length shorter than 6 mm; corium lacking transverse whitish callose band; humeral angle tapering into medium-sized acute spine (Fig. 6) ............................................................... Cl. saphisa n. sp.

4’. Total body length larger than 8 mm; corium with wide transverse whitish callose band; humeral angle tapering into large acute spine (Fig. 5) .................................................................... Cl. mackayensis Distant

5. Outer border of antenniferous tubercle armed with short acute spine; antennal segment IV fusiform, elongate; apical third of tibiae and tarsi shiny reddish; apical edge of corium lacking ivory to whitish discoidal spot; humeral angle tapering into large acute spine (Fig. 8) .................................................. C. saucius Stål

5’. Outer border of antenniferous tubercle unarmed; antennal segment IV subclavate, shorter; apical third of tibiae and tarsi not shiny reddish; apical edge of corium with ivory to whitish discoidal spots; humeral angle obtuse or subacute or with medium-sized spine (Figs. 7, 9).............................................................. 6

6. Humeral angle obtuse or tapering into short subacute spine (Fig. 9); head and pronotum with wide black to reddish brown stripe, this usually reaching base of scutellum .......................................... C. similis Blöte

6’. Humeral angle tapering into medium-sized acute spine (Fig. 7); head and pronotum with indistinct black stripe ................................................................................................................................... C. minutus Blöte