Data from: Biosystematics of Platanthera bifolia s.l. (Orchidaceae): Inferences from analysis of Scandinavian population samples

Over the years, various authors have (sub)divided the Eurasian moth
pollinated Platanthera bifolia into several taxa. Advanced studies using
multivariate morphometric analysis and/or genetic fingerprinting have all
included regions where the situation appears particularly complex. With
the aim to resolve variation patterns in a region where the situation
seems less complex, we analysed morphometric and AFLP data from 13
Scandinavian populations using a range of uni- and multivariate
statistical methods. Variation was largely continuous, though with
(individuals from) short-spurred and long-spurred populations,
respectively, forming loose groups. Provided that successful pollinator
shifts usually occur between moth species with small difference in
proboscis length, this pattern is congruent with the hypothesis that spur
length in P. bifolia s.l. has mainly evolved through pollinator shifts
followed by selection in response to proboscis length of the prevailing
local pollinator species. Acknowledging an important adaptive role of spur
length, observing that spur length was among the main contributors to
morphological variation, and noting this pattern to be congruent with both
AFLP patterns and habitat requirements, we advocate the formal distinction
between a short-spurred and a long-spurred taxon. Adopting the operational
definitions of species, subspecies and variety provided in Flora Nordica,
the two taxa should be recognized as P. bifolia var. bifolia and P.
bifolia var. latissima, respectively. A key to the varieties is provided.