Key to the identification of C. obsoletus species group from Indo-Burma

1. Eyes large, their diameter 1.1–1.2 times interocular distance, phallus slender, parallel-sided in apical half (Fig. 20). ........................................................................................................................................................ C. bolavensis sp. n.

- Eyes smaller than their frontal interocular distance...................................................................................................... 2

2. Eye diameter at most 0.7 times frontal interocular distance......................................................................................... 4

- Eye diameter more than 0.7 times frontal interocular distance .................................................................................... 3

3. Phallus parallel-sided in most of its length, only slightly wider in apical third (Fig. 24). The maximum eye diameter in the lateral view 0.78 times frontal interocular distance ................................................................. C. matsudai sp. n.

- Phallus is the widest in its apical two fifths of length, getting narrow to the apex (Fig. 29). The maximum eye diam- eter in the lateral view 0.85 times frontal interocular distance ........................................................ C. kundratai sp. n.

4. Phallus robust, parallel-sided in whole length (Fig. 30) ........................................................................ C. testaceus Pic

- Phallus wider in middle (Fig. 25) or apical part of its length (Figs 23–24, 26–28)...................................................... 5

5. Phallus wide in middle of apical part and gradually narrower towards middle and apex (Figs 26, 27) ...................... 6

- Phallus almost parallel-sided in wider apical half ...................................................................................................... 7

6. Phallus 6.5 times longer than wide at the widest part (Fig. 26) ....................................................... C. dembickyi sp. n.

- Phallus 8.0 times longer than wide at the widest part (Fig. 27) ........................................................ C. hergovitsi sp. n.

7. The apical half of phallus slightly slenderer towards apex (Fig. 23) .................................................... C. jendeki sp. n.

- The apical part or phallus parallel-sided (Fig. 28) ........................................................................... C. yunnanus sp. n.

*Only males can be identified by the key. The female genitalia and the size of eyes in females are uniform in Cautires . The differences in the shape of pronotum and antennae, body colouration or structure of pronotal ridges are minute and highly variable and they cannot support reliable identification. Cautires regalis is known only in female, and therefore was omitted from the key. Due to the inadequate description and unavailable type specimen, C. inapicalis was also omitted from the key.