Hebridean Marsh Orchid - Dactylorhiza ebudensis

Hebridean Marsh-orchid, D. ebudensis, has never been elevated to species status by the majority of  orchidologists. However, I have awarded it its own page here because it stands out enough to warrant its own space. The flowers are deeply coloured, reddish purple, with a three-lobed lip. The spike is said to be noticeably one-sided. The  leaves may be heavily blotched purple, typical of other hyper-pigmented  Marsh-orchids of the north and west of Britain. The plants are short and stocky, but that may be a reflection of where it grows. It is known essentially from the machair on North Uist where it flourishes, though two small colonies have been found on neighbouring islands. This habitat can have only existed for a maximum of 3,000 years due to sea level changes. If the Hebridean Marsh-orchid arose from a unique polyploid event, it was the most recent involving British Dactylorhiza. If so, the spotted orchid ancestor has been proposed as D. fuchsii hebridensis, with the other being D. incarnata ssp coccinea, both of which are present nearby and presumably were present then.

A recent evaluation of this plant, using molecular techniques, has placed it as a sub-species of D. traunsteineroides. They share the same fuchsii plastid haplotypes, but those are common haplotypes, also found in Northern Marsh-orchids. The analysis showed that D. ebudensis had a higher proportion of a D. incarnata haplotype. Analysis of a single specimen previously, with this finding, prompted the possibility that the parentage involved in the original polyploidy event was a maternal incarnata and a paternal fuchsii. This is opposite to the other Marsh-orchids, however it is now proposed that the incarnata components come from hybridisation and introgression with D. incarnata ssp coccinea, followed by a degree of genetic stabilisation. However, it was concluded that this data does not eliminate the possibility that D. ebudensis is a Marsh-orchid in its own right, but it does reduce the chances of that possibility. Studies of the ITS regions produced the conclusion that while the other four allotetraploid Marsh-orchids can easily be separated ebudensis sits close to traunsteineroides.
One unique feature is that D. ebudensis, if it is a subspecies of D traunsteineroides, is that it represents the evolution of a new form from one growing in a specialised habitat (fen) to one in a contrasting, but still specialised habitat (machair).
DNA methylation studies place ebudensis as far away from (or as close to) the Scottish D. traunsteineroides as those are from the Yorkshire D. traunsteineroides.

Despite the evidence I find it hard to see as ebudensis as a hyper-pigmented dwarf form of traunsteineri. There already is a hyper-pigmented variety of traunsteineroides - var lapponica. While the flower colour is different, the same shape prevails and it likes the same habitat, with lapponica often growing as a minority of the plants in a traunsteineroides colony.
Could D.ebudensis possibly have D.traunsteineroides as one of its parents? It is possible to have one 4n parent involved in a polyploid event as a few other polyploid Marsh-orchids have D. maculata as an ancestor. This could this go some way to explaining the molecular similarities of the molecular data between D.ebudensis and D.traunsteineroides.

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