Scientists have discovered Europe's rarest species of orchid on a remote island in Portuguese Azores, 173 years after the flowers were first found.
The Hochstetter's Butterfly-orchid, newly recognised following application of a battery of scientific techniques, is arguably Europe's rarest orchid species.
Under threat in its mountain-top retreat, the orchid urgently requires conservation recognition, researchers said.
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The research team, led by Professor Richard Bateman in collaboration with local botanist Dr Monica Moura from University of the Azores and plant morphologist Dr Paula Rudall of the Royal Botanic Gardens Kew, originally viewed these butterfly-orchids as a simple, tractable system ideal for studying the origin of species and so they initiated a focused exploration of all nine Azorean islands.
"This remarkable species languished unrecognised for 173 years," said Bateman.
A combination of field and laboratory research soon showed that butterfly-orchids first colonised the Azores from the Mediterranean rather than from North America, rapidly undergoing miniaturisation of their ancestrally large flowers.
It proved easy to distinguish the widespread Short-spurred Butterfly-orchid (Platanthera pollostantha) from the rarer Narrow-lipped Butterfly-orchid (P micrantha) using morphology, DNA sequences, and the identities of mycorrhizal fungi associated with the roots of the orchids.
However, this 'simple' study was thrown into disarray when Moura explored remote dwarfed laurisilva forests along the highest volcanic ridge on the central island of Sao Jorge and found an unusual population of butterfly orchids.
"I immediately recognised the flowers as being exceptionally large for an Azorean butterfly-orchid and e-mailed images to Bateman for confirmation that they were new to science," said Moura.
Data gathered subsequently in the laboratory using several analytical techniques all pointed to the discovery of a new species, and suggested that the species - named Platanthera azorica - originated relatively recently by a remarkable restoration of the large-flowered morphology of its presumed mainland ancestor.
Bateman then realised that this "new" orchid had in fact been illustrated (but never correctly identified as a new species) in the first ever Flora of the islands, published in 1844, but thereafter had consistently been confused with other more frequent Azorean species.
The finding was published the journal PeerJ.
