Genus Dilacreon Fennah, 1980

Dilacreon Fennah, 1980: 242; Lӧcker et al., 2010: 7; Zhang & Chen, 2013a, 319.

Type species: Dystheatias orpheus Fennah, 1956b; by original designation.

Diagnosis. Body size. Moderate-sized species. Body strongly compressed laterally.

Head. Head including eyes nearly as wide as pronotum; length of head from base of frons to apex of anteclypeus not more than 2.5 times width of frons at widest part. Vertex much broader than long in midline, anterior margin transverse, or slightly concave, or weakly angulately produced; lateral carinae slightly elevated. Antennae short; not sunk in a pit; pedicellus subglobose, at most only slightly longer than broad; no subantennal process present. Frons not or only slightly depressed basally, median carina simple, sometimes attaining basal margin, sometimes not; maximum width of frons no more than twice apical width; position of maximum width of frons distinctly dorsad of center of frontoclypeal suture; lateral carinae slightly elevated. Frontoclypeal suture distinctly semicircular or triangular, bent upwards, median part not reaching lower margin of antennal scape.

Thorax. Angle of hind margin of pronotum more or less rectangular. Forewing steeply tectiform; first crossvein MP 3+4 -CuA 1 less than half as long as vein MP 3+4 from MP fork to first crossvein MP 3+4 -CuA 1 and much shorter than first veinlet r-m; a supernumerary crossvein sometimes present between MP and CuA 1 close to fork CuA; RP apically bifid; 9–10 apical cells. Wing with R simple. Legs: Hind tibia without lateral spine; 1st hind tarsus with more than 5 teeth apically.

Male genitalia. Pygofer symmetrical; anal segment symmetrical or asymmetrical; gonostyli symmetrical in ventral view; aedeagus with process.

Female genitalia. Ovipositor elongate, orthopteroid, slightly curved upwards, reaching but not surpassing anal style; sternite VIII medially very long, slightly bent dorsad, posterior margin U-shaped; anal segment square (as long as wide) or rectangular (wider than long) in dorsal view; anal style as long as wide or slightly longer than wide; tergite IX without wax plates.

Distribution. Oriental and Australian regions.

Key to the species of Dilacreon Fennah of the world

1. Frons with lateral margins almost laterally produced; forewing with a crossvein MP-CuA 1 near CuA fork............... 2

- Frons with lateral margins distinctly anterolaterally produced; forewing without crossvein MP-CuA 1 near CuA fork....... 9

2. Apical lobes of anal tube with a pointed tip in lateral view..................................................... 3

- Apical lobes of anal tube with a rounded tip in lateral view.................................................... 4

3. Periandrium of aedeagus ventrally with one triangle and one ovoid shaped, flattened ridge (Löcker et al., 2010: Fig. 14A, B)....................................................................... D. (Dilacreon) granulinervis (Muir)

- Periandrium of aedeagus ventrally without above ridge (Fennah, 1980: Figs 13, 14)............ D. (D.) semiramis Fennah

4. Periandrium without process ventrally..................................................................... 5

- Periandrium with process(es) ventrally.................................................................... 6

5. Endosoma (=flagellum) left laterally with a spinous process in the middle (Löcker et al., 2010: Fig. 13A).................................................................................................. D. (D.) akethe Löcker

- Endosoma left laterally without process in the middle (Löcker et al., 2010: Fig. 15A)................ D. (D.) ispi Löcker

6. Spinous process on ventral surface of periandrium near apex (Fennah, 1980: Figs 20, 21)....... D. (D.) nigricornis Fennah

- Spinous process on ventral surface of periandrium not near apex................................................ 7

7. Apex of endosoma with a long spinous process (Fig. 2H–K)............................. D. (D.) deltodontus sp. nov.

- Apex of endosoma without process....................................................................... 8

8. The pair of spinous process at the base of the endosoma symmetrical (Fennah, 1956b: Fig. 16g)... D. (D.) telamon (Fennah)

- The spinous process at the left base of the endosoma strongly sinuate and that on the right straight (Fennah, 1956b: Fig. 16c)................................................................................ D. (D.) orpheus (Fennah)

9. Forewing with crossvein CuA 1 -CuA 2 present.............................................................. 10

- Forewing with crossvein CuA 1 -CuA 2 absent............................................................... 18

10. Anterior margin of vertex straight or very weakly convex, transverse........................................... 11

- Anterior margin of vertex angulate...................................................................... 15

11. Forewing with crossvein MP 3+4 -CuA 1 present.............................................................. 12

- Forewing with crossvein MP 3+4 -CuA 1 absent............................................................... 13

12. Periandrium with a lobe on right ventrally at apex produced into four spinous processes (Fennah, 1980: Figs 39, 40).................................................................................. D. (Eluzalmon) vashni Fennah

- Periandrium with a spinous process ventrally near apex (Fennah, 1980: Figs 31, 32)........... D. (E.) idomeneus Fennah

13. Vertex with broader at anterior margin than long in middle about 1.7: 1 (Fennah, 1980: Fig. 69)... D. (E.) pictifrons Fennah

- Vertex with broader at anterior margin than long in middle about 2.1: 1.......................................... 14

14. Antennae tawny; abdomen dorsally brown; vertex in profile obtusely angulately meeting frons; first crossvein r-m slightly basad of fork MP................................................................ D. (E.) parmenion Fennah

- Antennae creamy white; abdomen dorsally creamy white; apex of vertex in profile evenly rounding into frons; first crossvein r-m at same level as fork MP......................................................... D. (E.) caudatus Fennah

15. Periandrium with a large vertical triangular lobe ventrally in basal 1/2, acuminate apically and bent to left (Fennah, 1980: Figs 118, 119)........................................................................... D. (E.) salma Fennah

- Periandrium without such lobe ventrally.................................................................. 16

16. Periandrium with a spinose process on dorsal margin at middle (Fennah, 1980: Figs 92, 93)..... D. (E.) chionomus Fennah

- Periandrium without spinose process on dorsal margin....................................................... 17

17. Vertex with broader at anterior margin than long in middle about 1.4: 1; forewing with crossvein MP 3+4 -CuA 1 present (Fennah, 1980: Fig. 107)................................................................. D. (E.) pentagonus Fennah

- Vertex with broader at anterior margin than long in middle about 1.9: 1; forewing with crossvein MP 3+4 -CuA 1 absent (Fennah, 1980: Fig. 98).................................................................... D. (E.) themistius Fennah

18. Vertex without middle carina........................................................................... 19

- Vertex with middle carina.............................................................................. 22

19. Forewing with fork Sc+RP distad of fork CuA 1 +CuA 2 (Fig. 20C)............................. D. (E.) falcatus sp. nov.

- Forewing with fork Sc+RP basad of fork CuA 1 +CuA 2....................................................... 20

20. Forewing with markings............................................................................... 21

- Forewing without any markings......................................................... D. (E.) gibber Fennah

21. Forewing without a spot at fork CuA and with a diffuse cloud across membrane between apical angle and apex of clavus (Fennah, 1980: Fig. 85)............................................................. D. (E.) sordidus Fennah

- Forewing with a spot at fork CuA and without above cloud (Fennah, 1980: Fig. 46).................. D. (E.) koa Fennah

22. Apical part of gonostyli acute in lateral view............................................................... 23

- Apical part of gonostyli round in lateral view.............................................................. 25

23. The ventral margin of periandrium without spinous process (Fig. 9H–K).................... D. (E.) biprocessus sp. nov.

- The ventral margin of periandrium with process(es)......................................................... 24

24. The ventral margin of periandrium with a spinous process and left side without process basally (Fig. 4H–K)............................................................................................. D. (E.) apiculatus sp. nov.

- The ventral margin of periandrium without process and left side with a spinous process basally (Fig. 15H–K)............................................................................................. D. (E.) distentus sp. nov.

25. The dorsal margin of periandrium with a sinuous spinous process in the middle (Fig. 7H–K)....... D. (E.) arcuatus sp. nov.

- The dorsal margin of periandrium without spinous process.................................................... 26

26. Endosoma with a sheet-like process (Fig. 23J–M).................................... D. (E.) lobatus Zhang & Chen

- Endosoma without sheet-like process.................................................................... 27

27. Base of endosoma with a short erect spinous process (Fig. 17H–K)............................ D. (E.) erectus sp. nov.

- Base of endosoma without erect spinous process............................................................ 28

28. The right side of periandrium with two spinous processes apically (Fig. 25H)............. D. (E.) parapentagonus sp. nov.

- The right side of periandrium with one spinous process apically............................................... 29

29. The spinous process on the right apex of periandrium with its apical 1/3 bent to the left through a strong arc over the dorsal margin (Fig. 28H–K)............................................................. D. (E.) transversus sp. nov.

- The spinous process on the right apex of periandrium not bent to the left (Fig. 12H–K)...... D. (E.) congjiangensis sp. nov.