Tackling relationships and species circumscriptions of <i>Octoblepharum</i>, an enigmatic genus of haplolepideous mosses (Dicranidae, Bryophyta)

The systematic position of the tropical moss genus <i>Octoblepharum</i> remains under discussion, and in addition, species circumscriptions and relationships of its 18 accepted species remain poorly known. Here we analysed 21 <i>Octoblepharum</i> samples representing four species (<i>O. albidum</i>, <i>O. arthrocormoides</i>, <i>O. cocuiense</i>, <i>O. pulvinatum</i>), within a dataset of haplolepideous mosses and markers from all three genomes. <i>Octoblepharum</i> is resolved as monophyletic and sister to the Calymperaceae, and this clade as sister to the Hypodontiaceae. Based on the molecular results and morphological characters, we suggest <i>Octoblepharum</i> to be placed in its own family, the Octoblepharaceae. The analysed <i>Octoblepharum</i> species are molecularly clearly distinguishable. The two included specimens of the rare and little known Asian species <i>O. arthrocormoides</i> were originally labelled as the common and widespread <i>O. albidum</i>, and their recognition may represent the first records of the species after its description. <i>Octoblepharum albidum</i> shows considerable intraspecific molecular variability, which may correspond to morphologically distinguishable groups within a species complex.