Clarified relationship between Dactylorhiza viridis and Dactylorhiza iberica renders obsolete the former genus Coeloglossum (Orchidaceae: Orchidinae)

Abstract

Summary. Two decades have passed since DNA evidence first demonstrated an intimate relationship between the circumboreal species 'Coeloglossum' viride and the temperate Eurasian genus Dactylorhiza s.s. Most subsequent molecular phylogenies showed 'C.' viride to diverge after the D. incarnata group. The law of monophyly therefore dictated inclusion in Dactylorhiza of 'C.' viride, irrespective of its undeniably distinctive morphology. Those orchid enthusiasts still determinedly seeking reasons for retaining the genus Coeloglossum have often used as a justification the one published molecular study that suggested that D. viridis diverged earlier than D. incarnata. Interestingly, these respective phylogenetic positions are supported by recent data-rich studies based on next-generation sequencing. However, recent DNA phylogenies also show that D. iberica -long regarded as morphologically distinct but nonetheless universally accepted as belonging within the genus -diverged penecontemporaneously with D. viridis. Thus, in order to justify maintaining 'Coeloglossum' as a separate monotypic genus it would also be necessary to transfer D. iberica to a new monotypic genus, thus recognising two genera that are not only monotypic but also show only modest molecular divergence from the remaining dactylorchids. Examining in greater detail the morphology and micromorphology of D. viridis and D. iberica, we show that both species possess multiple morphological character states that are unique within the genus Dactylorhiza, but argue that greater phenotypic disparity is commonly the case in early-divergent lineages per se. Review of previous publications discussing D. iberica revealed little knowledge of its autecology, and contradictory DNA-based inferences that can be traced back to just two original specimens. We also suggest that morphological and molecular variation within both species has been under-estimated and under-explored.

Molecular Evolution of Chloroplast Genomes of Orchid Species: Insights into Phylogenetic Relationship and Adaptive Evolution

“…In recent years, the fast progress of next-generation sequencing technology has provided a good opportunity for the study of genomic evolution and interspecific relationships of organisms based on large-scale genomic dataset resources, such as complete plastid sequences [ 12 , 13 ]. The chloroplast (cp) is made up of multifunctional organelles, playing a critical role in photosynthesis and carbon fixation [ 5 , 14 , 15 , 16 ].…”

“…Due to its maternal inheritance and conserved structure characteristics [ 24 , 25 , 26 , 27 ], the cp genomes can provide abundant genetic information for studying species divergence and the interspecific relationships of plants [ 28 , 29 , 30 , 31 ]. For example, based on complete cp genomes, some studies suggested that Dactylorhiza viridis diverged earlier than Dactylorhiza incarnate [ 12 ]; Lepanthes is was distinct from Pleurothallis and Salpistele [ 13 ]. In addition, some researchs based on one nuclear region ( ITS - 1 ) and five chloroplast DNA fragment variations revealed that Bolusiella talbotii and the congeneric B. iridifolia were clustered into an earlier diverged lineage [ 10 ].…”

Pollinators and visitors of the generalized food-deceptive orchid Dactylorhiza majalis in North-Eastern Poland

“…Such a long proboscis can reach the base of the spur of D. majalis andin the same momentthe viscidium can adhere to the insect's head. The D. majalis spur is a medium-length spur, according to the phylogenetic classification in the Dactylorhiza genus (Adcock et al 1983;De Hert et al 2012;Radak et al 2012;Trunschke et al 2017;Bateman and Rudall 2018). The fit between the D. majalis spur ca.…”

Comparison of labellum and spur papillae in Dactylorhiza (Orchidaceae) from Anatolia

“…Morphological features of Dactylorhiza are widely used in the classification of the taxa. The morphological differences in the labellum and spur are widely used to distinguish the taxa (Renz and Taubenheim 1984;Bateman and Rudall 2018). However, the labellum and spur structures can be similar in some of the taxa.…”

“…However, this excludes Dactylorhiza viridis (L.) R. M. Bateman, Pridgeon & M. W. which was previously named Coeloglossum viride (L.) Hartm. (Bateman and Rudall 2018). For this reason, it is called as deceptive genus (Claessens and Kleynen 2013).…”