Reassessing the taxonomic diversity of Plagiothecium section Orthophyllum in the North American bryoflora

Abstract

At the beginning of the twentieth century, Plagiothecium nemorale s.l. and P. succulentum, both belonging to P. sect. Orthophyllum, were considered to be distributed across almost the entire Northern Hemisphere. However, in the mid-twentieth century these taxa were recircumscribed resulting in their exclusion from the North American bryoflora and restricting their distributions to Asia and Europe, and in the case of Plagiothecium nemorale s.l., also North Africa. More recently, it was found that P. nemorale s.l. is a taxonomic complex comprising three distinct species: P. nemorale s.s., P. longisetum, and P. angusticellum. I revised the North American material of P. section Orthophyllum deposited in three herbaria (NY, FH, F) and found that five examined taxa of the section are present in the North America. Two of the species P. angusticellum and P. longisetum, have not been recorded from North America previously, while two others, P. nemorale and P. succulentum, had not been listed in the North American bryoflora for 50 years. One taxon is new for the U.S.A. – P. succulentum f. propaguliferum. Here I provide detailed descriptions of the anatomical and morphological features of the recorded taxa along with photographic documentation of their most important characteristics. I also summarize their known distributions in North America and ecological preferences and provide a key for their identification.

The Genus Plagiothecium Schimp. (Plagiotheciaceae, Bryophyta) in Eurasia: An Annotated Checklist with Distribution and Ecological Data

“…Distribution . Apart from Eurasia, this species is also reported from North America (Canada, USA) [ 191 ].…”

“…Distribution . Apart from Eurasia, this species is also reported from North Africa (a single record from Tunisia) [ 47 ]; and from North America (Canada, USA) [ 191 ].…”

“…The species is quite common in Eurasia [27]. It is also reported by Ros et al [12,47] from North Africa (Algeria, Tunisia) and reported from North America (Canada, USA) [27,191]. 29.…”

“…From Poland (from where it was described), this species was recorded mainly in deciduous forests (e.g., eutrophic swamp forests Ribeso nigri-Alnetum Sol. [191].…”

“…Currently, P. succulentum fo. propaguliferum is recorded in Western, Northern and Western Europe [7], and from North America (Canada, USA) [7,191]. 40.…”