Key to the Chinese species of formicarius ­group of Exallonyx

1. Flagellum with tyloids ......................................................... E. laevigatus Fan and He

­ Flagellum without tyloids .......................................................................................... 2

2(1). Abdominal petiole contracted at base ........................................................................ 3

­ Abdominal petiole not contracted at base.................................................................. 4

3(2). Second flagellar segment 2.7× as long as wide; abdominal petiole 1.0× as long as deep in lateral view with six diagonal longitudinal ridges .............. E. strictus sp. nov.

­ Second flagellar segment 3.4× as long as wide; abdominal petiole 2.0× as long as deep in lateral view with four diagonal longitudinal ridges E. pingbianensis sp. nov.

4(2). First thyridium 1.8–2.0× as wide as long................................................................... 5

­ First thyridium 2.5–3.5× as wide as long................................................................... 6

5(4). Clypeus 3.1× as wide as long; median groove on syntergite reaching 0.5 to space between tyridia, with two lateral grooves 0.67× as long as median groove ............... .............................................................................................. E. ejunicidus He and Fan

­ Clypeus 2.5× as wide as long; median groove on syntergite reaching 0.7 to space between thyridia, with two lateral grooves 0.2× as long as median groove ................ ............................................................................................. E. fujianensis Fan and He

6(4). First thyridium 2.5× as wide as long ........................... E. chiuae Townes and Townes

­ First thyridium 3.1–3.5× as wide as long................................................................... 7

7(6). Upper margin of pronotum with 2 rows of setae .................... E. fuliginis He and Fan

­ Upper margin of pronotum with single row of setae ......... E. nigricornis He and Fan