Identification key to Vietnamese species of sect. Paniculatum.
1a. Lip mid-lobe flush with the front side of the spur; stipes with very broad upper parts enveloping the pollinia	C. equestre Seidenf.
1b. Lip mid-lobe oriented at an obtuse angle to spur; stipes not enveloping the pollinia	2
2a. Septum in the spur complete (from wall to wall); inflorescence pendulous	C. duplicilobum (J.J.Sm.) Garay
2b. Septum in the spur incomplete (occasionally reaching the backwall in distal part of the spur); inflorescence erect to semi-erect	3
3a. Spur distinctly curved forward; mid-lobe of the lip straight, with slightly upward-pointing tip	C. inflatum (Rolfe) Garay
3b. Spur straight; mid-lobe of the lip distinctly upward-pointing	C. paniculatum (Ker Gawl.) Garay

Note: C. chapaense (Guill.) Garay reported from Vietnam by [24] as a separate species is considered to be a synonym of C. paniculatum (Ker Gawl.) Garay [51].