Phylogeny, species delimitation and taxonomy in Polytrichum sect. Polytrichum (Polytrichaceae Schwagr.; Bryophyta)

• Main Author: Kariyawasam, Isuru Udayanga
• Other Authors: Bell, Neil, Kidner, Catherine, other
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: The University of Edinburgh 2021
• Subjects: plant taxonomy; Bryophytes; Polytrichaceae; phylogeny; Arctic; Subarctic
• Online Access: https://hdl.handle.net/1842/38469; https://doi.org/10.7488/era/1733

The Polytrichaceae Schwägr. is a relatively a small, distinct family of mosses (Phylum Bryophyta) usually recognised in its own order and class, Polytrichales and Polytrichopsida. The presence of the characteristic “polytrichoid peristome”, lamellae on the adaxial side of the leaf, well developed conducting tissue and the occurrence of some robust species with heights of >40–60cm are some of the defining characters of the family. The type genus of Polytrichaceae, Polytrichum Hedw. comprises three sections viz. Polytrichum section Polytrichum, section Aporotheca and section Juniperifolia. The section Polytrichum is a well-circumscribed clade that includes eight species and all plants currently recognised within the species concept of Polytrichum commune Hedw., one of the most widespread and ecologically important moss species of northern temperate and boreal regions across Asia and North America and also known from southern temperate areas. Although some molecular taxonomic and monographic work has been done for certain genera within the family over the past three decades, a comprehensive integrated (molecular and morphological) taxonomic revision has not been done for Polytrichum sect. Polytrichum, which contains the type species of the genus, P. commune Hedw. This study presents the first robust molecular phylogenetic framework for Polytrichum sect. Polytrichum using both Sanger and Next Generation Sequencing (NGS) approaches. For Sanger sequencing, a robust taxon sampling (114 ingroup accessions) was done to cover a substantial geographic distribution and morphological diversity. Six molecular markers were used, including two nuclear markers (ITS1 and ITS2) and four plastid markers (rbcL, trnL-F, rpl16 and trnG). Phylogenetic relationships of the species were tested for the concatenated (3851 bp) matrix using both Maximum Likelihood (ML) and Bayesian inferences. The monophyly of five clades was strongly supported within Polytrichum sect. Polytrichum [Arctic and Subarctic P. swartzii and P. jensenii clades, ...