Molecular species delimitation of <i>Sphagnum</i> subgenus <i>Subsecunda</i> in Europe

Abstract A taxonomic revision of Sphagnum subgenus Subsecunda in Europe is warranted as the taxonomic status and the relationships among the six species found in Europe are inconsistent. To achieve this, we obtained a large specimen set from European herbaria and utilized two types of molecular markers combined with morphological examination. Our results support five distinct, highly genetically variable Subsecunda taxa in Europe, excluding S. pylaesii due to missing data. Three haploid taxa correspond to the morphological description of the species S. contortum, S. platyphyllum, and S. subsecundum. Our analyses support that S. gravetii belongs to S. inundatum, and that S. auriculatum and S. denticulatum are conspecific. Both taxa are diploid, but none of the studied haploid taxa was identified as their parental species. Furthermore, one deviating specimen of S. auriculatum from the Azores was haploid and probably represents another, undescribed taxon of subgenus Subsecunda in Europe. Morphological identification of, in particular, the diploid species of Subsecunda can be challenging, and hence may have to be confirmed by genotyping in some instances. The results based on single nucleotide polymorphisms and microsatellite markers largely agree and highlight that microsatellites, which are often easier to obtain, are reliable in resolving taxonomic issues in Sphagnum.