O. chaonica was first described from Epirus by Kreutz and Heitz as O. mammosa subsp. parviflora in 2013 and subsequently promoted to full species status by Delforge in 2015. Its name refers to the ancient region of Chaonia in north western Epirus, northern Greece.

This is a member of the sometimes confusing  O. mammosa group but unlike many of its cousins, one which exhibits several features that simplify identification. The first and most obvious characteristic is that it's very small in all its parts, the plant is invariably less than 20cms in height  and the flowers are few in number (two to four), not much more than half the size of the bigger but similar O. epirotica. The lateral sepals are long, green flushed pink and swept back whereas the dorsal sepal is bent forward, often strongly so. The lip is heart shaped with a yellow margin and moderately developed protuberances that are glabrous inside and very hairy on the outside.

Its distribution is not fully understood but is known with certainty from a triangular area formed by Grevena, Ioannina and Larissa where it prefers grassland and waste areas with some shrub cover, normally on calcareous soils. Although several populations have been reported, the individual plants within them is generally small. The photo dates from the end of April at which time flowering was just beginning.