This species was first described by Paulus in 2007 from the Spili valley in Crete and its name derives from the mythological Cretan Princess, Phaedra. The discovery and formal recognition of O. phaidra was the result of a wider study of the island's late flowering O. fusca group populations.

O. phaidra is endemic to Crete but is not at all uncommon and appears to be spread widely across suitable habitats throughout the island. Its distribution includes the Thripti mountains and it is therefore in contact with several other of the numerous Cretan Pseudophrys species in that area, not least the similar O. pallidula. It can also be mistaken for the widespread O. creberrima but differs from this species primarily by the deeper and longer central groove separating the lip, which also tends to be flatter and less recurved at the margins. Importantly it is a later flowerer and although the two species may be found growing concurrently, O.phaidra will be at its best when the flowers of O. creberrima  are fading.

O. phaidra and O. pallidula share identical habitat preferences and flower at a similar time, its therefore unsurprising that hybridization is recorded, although the pollinator of O. phaidra has yet to be identified. This species flowers during April and early May and the picture here was taken at a well known site above the village of Spili on the 17th of April.