Key to the world fauna of the Genus Cyanopenthe Nikitsky, 1998

1. Pronotum densely and coarsely punctate; scutellum bronzed or reddish bronzed, triangular, without distinct impression (Fig. 1). Bhutan and North India ..................................................... C. metallica (Champion, 1916)

- Pronotum sparsely and finely punctate; scutellum black, transverse, with rounded apex, with distinct, dark rounded impression in middle........................................................................................... 2

2. Antennomeres III–V slightly more slender, projections of antennomeres VIII–IX longer than that of antennomere X (Fig. 8); paraproct shorter, about 1.2X as long as wide (Fig. 27). Thailand ................... C. thailandica Nikitsky, 1998 (Fig. 2)

- Antennomeres III–V slightly thicker, projections of antennomeres VIII–IX as long as or shorter than that of antennomere X; paraproct longer, about 1.4–1.6X width. Taiwan ............................................................. 3

3. Elytra and abdomen more rounded (Fig. 15), ratio of body width to length 1.0:1.4–1.5; anterolateral margin of pronotum more rounded (Fig. 13); aedeagus: lateral margins of apical piece of tegmen slightly convergent distally, median lobe about 1.05X as long as tegmen; ovipositor: proctiger slightly wider in ventral view............................... C. taiwana sp. nov.

- Elytra and abdomen more elongated (Fig. 16), ratio of body width to length 1.0:1.5–1.6; anterolateral margin of pronotum less rounded (Fig. 14); aedeagus: lateral margins of apical piece of tegmen subparallel to slightly divergent distally, median lobe about 1.10X as long as tegmen; ovipositor: proctiger slightly more slender in ventral view................ C. leei sp. nov.