Molecular phylogeny of Plagiothecium and similar hypnalean mosses, with a revised sectional classification of Plagiothecium

Abstract

We investigated the systematic relationships within the pleurocarpous moss genus Plagiothecium, based on cladistic analyses of sequence data from one nuclear (ITS) and two plastid (trnK-psbA (matK) and rpl16 intron) DNA regions for 110 specimens of Plagiothecium and similar hypnalean mosses. Plastid and nuclear trees were mostly similar, but differed in the placement of several species of Plagiothecium, and in the relationships among other genera. The phylogenetic hypotheses based on plastid markers were well resolved; in contrast, nuclear data were insufficient to resolve some of the lowest-level relationships within the genus. In the main Plagiothecium is natural, includes more taxa than are often recognized, and is most closely related to Isopterygiopsis and Herzogiella. Nine sections are recognized within Plagiothecium, four new: Section Pseudo-Neckera to accommodate P. neckeroideum and its allies, Section Ortholimnobium for P. handelii and P. paleaceum, Section Struckia for P. argentatum and P. enerve, and Section Rectithecium for P. piliferum. The geographical distribution of the sections suggests that Plagiothecium originated in Asia. The derived, mainly autoicous sections Plagiothecium and Leptophyllum may have spread to the Southern Hemisphere through long distance dispersal. Three new species in section Leptophyllum (P. funale, P. pacificum and P. rhizolucidum) and two new taxa in section Pseudo-Neckera (P. decoratum and P. neckeroideum fo. exile) are described. A limited phylogenetic hypothesis for the superficially similar hypnalean genus Taxiphyllum, which was used as outgroup, is included. A related genus (Longiella) is described, with a single species (L. plagiothecioides). The aquarium species T. barbieri is transferred to Ectropothecium.

Resurrection of the Plagiothecium longisetum Lindb. and proposal of the new species—P. angusticellum

“…Genetic distance between P. nemorale and Wolski specimens based on the concatenated matrix was between 0.0026 and 0.0078 (S6 Table). Lower distance was recorded for P. longisetum-up to 0.0047, while higher for the P. angusticellum (Wolski 1,5,22,23,24,25,26,28,29)-from 0.0052. The separateness of both groups in concatenated matrix is most strongly confirmed by the rpl16 marker (S7-S9 Tables).…”

“…Recent articles about the genus Plagiothecium [4][5][6][7] supported by molecular analyses show a new point of view on the relationship between individual taxa of this genus. The genus is not only described as extremely variable but also comprises several dozen taxa awaiting detailed research and determination of their taxonomic status [4].…”

“…To formulate a proper hypothesis about the phylogeny of Plagiothecium-a group which represents complexes of closely related taxa-the molecular differences among both nuclear and chloroplast regions should be investigated [5]. Therefore, we have analysed the nuclear ITS and chloroplast the rps4 and rpl16 genes because they are frequently sampled markers in bryophyte phylogenies, and the latter can yield a phylogenetic signal even at the lowest population level [35].…”

“…The molecular research was based on nuclear and chloroplast DNA markers: ITS (from the 3' end of the hypervariable nuclear spacer ITS1, through the 5.8S gDNA, to the 5'end of the ITS2 spacer); rpl16 cpDNA gene encoding ribosomal protein L16; and rps4 cpDNA gene encoding ribosomal protein S4. Markers were selected based on Wynns et al [5] and Ignatova et al [7], which focus mainly on the genus Plagiothecium.…”

“…However, a recent revision [4] recognized 67 taxa belonging to this genus, while a further 46 names require detailed research to determine their taxonomic status. The number of recognized species has changed rapidly in recent years, which has been caused not only by an increased interest in research but also by the use of molecular methods for analysis [4][5][6][7].…”