Delimitation of taxa of Sphagnum subsecundum s.l. (Musci, Sphagnaceae) based on multienzyme phenotype and cytological characters

The aim of this study was to find diagnostic enzymatic markers for prompt identification of some taxa of Sphagnum having a unistratose cortex, referred to here as S. subsecundum sensu lato (section Subsecunda). Isozyme variants were studied in 417 plants deriving from many regions of the Northern Hemisphere. The multienzyme phenotypes (MEPs) confirmed the existence of groups that are correlated with morphological species: S. subsecundum Nees, S. inundatum Russ., S. denticulatum Brid., S. lescurii Sull., and, treated as a point of reference, S. contortum Schulz. The results suggest the separateness of S. lescurii, treated sometimes as a synonym of S. denticulatum in the literature. The reports on ploidy levels of these taxa show discrepancies that need clarification. Therefore, a flow cytometric analysis of DNA content of 84 accessions was performed. In general, two ploidy levels are common in Sphagnum: haploid and diploid. The DNA content of haploid species studied here, S. subsecundum and S. contortum, was about 0.37 pg/nucleus, and of diploid ones, S. denticulatum, S. inundatum, and S. lescurii, was about 0.72 pg/nucleus. On the basis of this study we can recommend flow cytometry as an exact and prompt method for DNA content estimation in Sphagnum.