Insights Into the Evolutionary History of the Subfamily Orthotrichoideae (Orthotrichaceae, Bryophyta): New and Former Supra-Specific Taxa So Far Obscured by Prevailing Homoplasy

Abstract

Mosses of the subfamily Orthotrichoideae represent one of the main components of the cryptogam epiphytic communities in temperate areas. During the last two decades, this taxonomical group has undergone an extensive revision that has led to its rearrangement at the generic level. However, their phylogenetic relationships and inferences on the evolutionary patterns that have driven the present diversity have little advanced. In this study, we present a dated molecular phylogenetic reconstruction at the subfamily level, including 130 samples that represent the 12 genera currently recognized within the subfamily, and the analysis of four molecular markers: ITS2, rps4, trnG, and trnL-F. We also analyze 13 morphological characters of systematic value to infer their origin and diagnostic utility within the subfamily. The phylogenetic reconstruction yields three main clades within the subfamily, two of which correspond to the tribe Zygodonteae, and one to Orthotricheae. Within Zygodonteae, the genus Zygodon results to be a polyphyletic artificial assembly, and we propose to separate a new genus named Australoria. Conversely, our results do not support the separation of Pentastichella and Pleurorthotrichum at the genus level and we therefore propose to include Pleurorthotrichum in Pentastichella. Regarding Orthotricheae, our analyses clearly allow the distinction of two subtribes: Orthotrichinae and Lewinskyinae. Within the latter, Ulota results a polyphyletic entity, and therefore we propose the segregation of a separate new genus named Atlantichella. Dating analyses allow us to conclude that the split of the tribes within Orthotrichoideae dates from the Middle Jurassic, while the diversification of Orthotrichum and Zygodon probably started during the Late Cretaceous. However, most of the extant genera of this subfamily seem to be younger, and apparently its highest diversification burst took place during the Oligocene. Finally, the analysis of the morphological traits reveals that most of the characters previously used to separate genera and here tested are homoplastic, which has hindered the taxonomical and systematic proposals for decades. However, even if there are no exclusive characters, all of the genera can be defined by the combination of a few characters.

An NGS-Based Phylogeny of Orthotricheae (Orthotrichaceae, Bryophyta) With the Proposal of the New Genus Rehubryum From Zealandia

“…Macromitrioideae is almost exclusively intertropical, whereas Orthotrichoideae is common in temperate and cold regions of both hemispheres, as well as in high tropical mountains. Orthotrichoideae is, in turn, divided into two tribes, Orthotricheae Engler and Zygodonteae Engler ( Goffinet and Vitt, 1998 ; Draper et al, 2021 ). Of these, Orthotricheae stands out as one of the main components of the epiphytic communities in temperate areas, both in dry ( Draper et al, 2006 ; Lara et al, 2009 ) and in oceanic or hyperoceanic conditions ( Garilleti et al, 2015 ; Lara et al, 2016 ).…”

“…In fact, the gametophytes of the different Orthotricheae species are overall morphologically similar, and few species within this group can be identified in the absence of sporophytes. This may be one of the reasons for the numerous taxonomic changes that this group has experienced during the last decades, involving rearrangements affecting the main genera ( Goffinet et al, 2004 ; Plášek et al, 2015 ; Lara et al, 2016 ; Draper et al, 2021 ).…”

“…For many years, Orthotricheae was understood to include only two large genera, Orthotrichum Hedw. and Ulota D.Mohr, but in the last 20 years, these two genera have been, respectively, split into five and three genera (see a revision in Draper et al, 2021 ). Two phylogenetic reconstructions including a representative selection of the Orthotricheae taxa as currently understood have been published recently ( Draper et al, 2021 ; Wang et al, 2021 ), based on the analyses of 4 nuclear and chloroplast loci, and 6 loci from all three plant genomes, respectively.…”

“…and Ulota D.Mohr, but in the last 20 years, these two genera have been, respectively, split into five and three genera (see a revision in Draper et al, 2021 ). Two phylogenetic reconstructions including a representative selection of the Orthotricheae taxa as currently understood have been published recently ( Draper et al, 2021 ; Wang et al, 2021 ), based on the analyses of 4 nuclear and chloroplast loci, and 6 loci from all three plant genomes, respectively. These two studies represent an important step forward for the understanding of the possible evolutionary history of this tribe.…”

“…Specifically, we intend to answer whether the nuclear data support the current delimitation of Orthotricheae at the genus level. As indicated above, this has been tested through the analyses of organellar genomes, but nuclear data have been restricted to the inclusion of ITS 2 and 26 S in the phylogenies by Draper et al (2021) and Wang et al (2021) , respectively. The epiphytic habitat is characterized by its low moisture retention capacity, which is especially harsh in areas with climates including a dry season (e.g., Pugnaire and Valladares, 1999 ).…”