Cynorkis Section Gibbosorchis H. Perr.
Rostellum entire with one part longer in front of the anther, divided and 3 lobed (2 arms and a median lobe), median lobe not inferior, supplementary; the arms to at least l mm long; median lobe obscurely ascending in front base of the lateral sepals and petals free or more or less joined basally; flowers generally large and brilliant, Labellum often 4 lobed (trilobed with the median lobe bifid).
Type species:
Cynorkis gibbosa Ridl.
Section represented in Madagascar by 16 species of which 14 are endemic and 2 (C. purpurascens and C. fastigiata) are special to the Malagash region.

Keys to the groups:

1 Labellum entire, trilobed or with 5 lobes, the inferior lobes reduced, in the last case, to 2 obtuse teeth Group 1
1a Labellum with 4 lobes or trilobed with the median lobe bifid or bilobed Group 2

New species and nomenclatural changes in Cynorkis (Orchidaceae: Orchidoideae) from Madagascar and the Mascarenes, Kew Bulletin volume 72, Article number: 38 (2017)

Cynorkis aconitiflora Hermans, Andriant. & Sieder Madagascar
Cynorkis christae Hermans, Andriant. & Sieder NW. Madagascar
Cynorkis elephantina Hermans, Andriant. & Sieder Madagascar
Cynorkis mammuthus Hermans & P.J.Cribb N. Madagascar
Cynorkis mangabensis Hermans & P.J.Cribb Madagascar
Cynorkis sanguinolenta Hermans, L.Gaut. & P.J.Cribb Madagascar
Cynorkis siederi Hermans & Andriant Madagascar
Cynorkis syringescens Hermans & P.J.Cribb Madagascar

World Checklist of Monocotyledons. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; accessed 03/04/2020