This taxon was originally considered to be one of three recognized varieties of O. ferrum-equinum, more  recently however, studies in Turkey and on the Aegean island of Samos seem to provide evidence for an uplift in status to full species. O. labiosa most frequently appears amongst colonies of the nominate race and where this occurs, intermediates between type and variety labiosa are not uncommon. The previously mentioned studies however, reveal that O. labiosa exists in pure populations (exclusively so on Samos) and exhibit a phenology that is noticeably different. The pollinator has yet to be discovered and so it could still be determined that O. labiosa falls within the natural varietal limits of O. ferrum-equinum, there is however a groundswell of expert opinion supporting separation of the two species. 

Lip markings are variable but typically exhibit a basic horseshoe shaped speculum that is seldom elaborate and often just two vertically parallel lines. Photo 9 is particularly interesting in that the lining of the speculum continues up to the basal field and round the neck of the stigmatic cavity, this being a characteristic more commonly noted in O. spruneri. The key identification feature is the strongly convex lip and spreading margins which gives it the face-on appearance of a frilled black olive !

It's range was once thought to be limited to Anatolia and the Aegean islands but is now known to be fairly widespread, albeit less common in mainland Greece. O. labiosa is thought to flower marginally earlier than O. ferrum -equinum, the examples illustrated here date from the first week of Arpil, coming from Chios, Cephalonia and Mount Hymettus near Athens.