Phylogenomics resolves the Himalayan endemic Brachymeniopsis gymnostoma (Bryophyta, Funariaceae), rediscovered after almost a century, as a species of Entosthodon

Traits of the spore-bearing generation have historically provided the basis for systematic concepts across the phylogenetic spectrum and depth of mosses. Whether taxa characterized by a simple sporophytic architecture are closely related or emerged from independent reduction is often ambiguous. Phylogenomic inferences in the Funariaceae, which hold the model taxon Physcomitrium patens, revealed that several such shifts in sporophyte complexity occurred, mostly within the Entosthodon-Physcomitrium complex. Here, we report the rediscovery, nearly 100 years after its description, of the Chinese endemic and monospecific genus Brachymeniopsis, which is characterized by, among other traits, its short sporophytes lacking the sporangial peristome teeth controlling spore dispersal. Phylogenomic inferences reveal that its sole species, B. gymnostoma arose within the clade of Entosthodon sensu stricto, a genus with typically long-exerted capsules. We therefore propose to transfer B. gymnostoma to the genus Entosthodon, as E. gymnostomus. Furthermore, Clavitheca poeltii, the sole species of the genus, is morphologically highly similar to E. gymnostomus, and should also be transferred to Entosthodon, but is retained as a distinct taxon, E. poeltii, until additional populations allow for testing the robustness of the observed divergence in costa and seta length between the Nepalese and Chinese populations.