Bryophytes of the Burmese amber forest: Amending and expanding the circumscription of the Cretaceous moss genus Vetiplanaxis

Abstract

Several sterile gametophyte fragments of pleurocarpous mosses preserved in Cretaceous amber from Myanmar are described. All inclusions share the presence of long and relatively thin-walled cells in the middle portion of the leaf lamina, a relatively narrow costa with dorsal teeth, slightly differentiated marginal cells, and almost exclusively unicellular teeth in the leaf margin, indicating affinities to hypnodendralean pleurocarpous mosses. Re-investigation of the holotype of Vetiplanaxis pyrrhobryoides from the same amber deposit allows for a revision of the current taxonomic treatment as a putative member of Rhizogoniales, and tentatively supports the original interpretation as a member of Hypnodendrales. Three further fossils are described as new species Vetiplanaxis espinosus, Vetiplanaxis longiacuminatus, and Vetiplanaxis oblongus. These new finds indicate that a diverse pleurocarpous moss flora was present in the Cretaceous amber forest of Myanmar, and mark this deposit as one of the most promising localities for reconstructing Cretaceous bryophyte floras.