Key to Deltocephalini from Thailand

1. Forewing with extra cross veins (Figs 1A–B; 3A–B; 5A–B).................................................... 2

- Forewing without extra cross veins........................................................................ 8

2. Crown more than 2x as long as width between eyes (Fig. 3A).................. Phetchabunia janteabi gen. nov., sp. nov.

- Crown at most as long as broad between eyes................................................................ 3

3. Crown shorter medially than next to eye, anterior and posterior margins sub-parallel (Fig. 1A)..................................................................................................... Loeia tampti gen. nov., sp. nov.

- Crown distinctly longer medially than next to eye............................................................ 4

4. Aedeagal shaft needle-like................................................................ Polyamia acicularis

- Aedeagal shaft not as above.............................................................................. 5

5. Crown conspicuously marked with brown, lower half of face completely brown, markings on anterior margin forming three yellow transverse spots and on crown forming subapical central yellow spot........................... Maiestas scripta

- Crown not marked as above.............................................................................. 6

6. Forewing marked with dark brown spots (Fig. 5A)............................................................ 7

- Forewing not marked with dark brown spots............................................ Matsumuratettix jaruphani

7. Subgenital plate macrosetae marginal (Fig. 6C); aedeagal shaft cylindrical (Fig. 6F)............. Maiestas subsirii sp. nov.

- Subgenital plate macrosetae central on plate; aedeagal shaft laterally compressed............ Matsumuratettix hiroglyphicus

8. Forewing marked with a zig-zag brown marking................................................ Maiestas dorsalis

- Forewing not marked as above............................................................................ 9

9. Crown not or only very slightly produced medially, with a dark brown transverse band on disc............ Paramesodes sp.

- Crown distinctly produced medially, without a transverse dark brown band on disc................................. 10

10. Anterior margin of crown dark brown with transverse row of white spots............................ Maiestas distincta

- Crown not marked as above............................................................................. 11

11. Face marked with dark brown spot below antennae and central brown spot on crown, or if spot on crown absent then crown without marking.......................................................................... Maiestas portica

- Face and crown not marked as above...................................................................... 12

12. Subgenital plates fused to valve......................................................... Miradeltaphus sanogae

- Subgenital plates not fused to valve....................................................................... 13

13. Aedeagal shaft curved dorsally with apical gonopore......................................................... 14

- Aedeagal shaft at most shallowly curved dorsally with gonopore apical on dorsal surface (Fig. 6F).................... 15

14. Aedeagal shaft with an apical notch...................................................... Deltocephalus vulgaris

- Aedeagal shaft without an apical notch................................................... Deltocephalus infirmus

15. Aedeagal shaft very elongate, bifurcate apically............................................... Yuanamia producta

- Aedeagal shaft short to moderately long not bifurcate apically (Figs 6E–F)....................................... 16

16. Aedeagus with well-developed basal heel................................................... Maiestas dinghuensis

- Aedeagus without developed basal heel........................................................ Maiestas serrata