Plagiothecium longisetum was described by Lindberg in 1872, based on Maximowicz materials from Japan. In the 1970s, this species was synonymized with P. nemorale. However, a polyphasic approach applied to the investigation of the P. nemorale sensu lato showed a clear separation between the specimens of former P. longisetum and the type of P. nemorale. Morphological features and molecular analyses provide evidence that those two groups are distinct, as well as allowed to describe the new species. The results are strongly supported by the statistical analyses of morphometric features and phylogenetic analyses based on concatenated nuclear and chloroplast DNA markers. The maximum likelihood (ML) and Bayesian inference (BI) analyses of ITS, rps4 and rpl16 regions place both species outside the P. nemorale group. The distinctions between individual species, reflected by the morphological features—easy to observe—and the molecular data, provide a scientific foundation for the resurrection of P. longisetum Lindb. and establishment of a new species–P. angusticellum sp. nov.

Wolski, G. J. 2017. Morphological and anatomical variability of Plagiothecium nemorale in Central Poland. — Herzogia 30: 36–50. Species in the genus Plagiothecium are highly variable, and one of them, Plagiothecium nemorale, is often described as a complex of species. The main aim of this study is to describe intraspecific variability of this taxon based on specimens collected in central Poland. The results suggest that specimens can be separated into two groups that differ in terms of the width of the leaf at the widest point, the length of the leaf cells and the diameter of the stem. Wolski, G. J. 2017. Morphologische und anatomische Variabilität von Plagiothecium nemorale in Zentralpolen. — Herzogia 30: 36–50. Die Arten der Gattung Plagiothecium sind sehr variabel, einige davon, wie Plagiothecium nemorale werden oft als Artenkomplex beschrieben. Das Hauptziel der Studie ist es, die innerartliche Variabilität von Plagiothecium nemorale, basierend auf Belegmaterial, das in Zentralpolen gesammelt wurde, aufzuzeigen. Die Ergebnisse der Studie weisen auf meist diskriminierende Eigenschaften hin, die es ermöglichen, das untersuchte Material in zwei sich unterscheidende Gruppen aufzuteilen. Die unterscheidenden Merkmale sind z. B. die Breite der Blätter, die Länge der Blattzellen und der Stämmchendurchmesser.

An annotated checklist of the pleurocarpous moss genus Plagiothecium in Eurasia is presented for the first time based on a thorough review of the literature. Data have been compiled from previous relevant works conducted on the genus over more than 70 years and published up to the end of June 2020 for 107 Eurasian countries (and islands). Sectional classification is based on molecular phylogeny of the genus published recently. A total of 41 taxa are reported, including 29 species and 12 infraspecific taxa (nine varieties and three forms) belonging to eight sections. The highest numbers of taxa were found in China (20 taxa), the Russian Federation (20 taxa) and Japan (18 taxa), while the smallest numbers of taxa were recorded in the Middle East, Central Asia and the islands area. Not a single species of Plagiothecium was recorded in 26 regions, whereas P. denticulatum, P. nemorale and P. cavifolium turned out to be the most widespread species in the entire study area. They were recorded in most of the surveyed countries and islands. For each accepted taxon, information on relevant literature, synonyms, distribution within Eurasia and globally are provided. Comments on each taxon, ecological preferences, and notes on doubtful records are also included. Additionally, distribution maps for each recognised taxon are supplied. This checklist can enlighten and foster a better understanding of the distribution, diversity, and ecology of Plagiothecium in Eurasia and provides an incentive for future research on the genus.

(2019). New national and regional bryophyte records, 58. Journal of Bryology. Ahead of Print.