A taxonomic revision of Hedwigia (Hedwigiaceae, Hedwigiales) in China

Hedwigia is a small genus that currently comprises only 12 accepted species. However, taxonomic issues within this genus remain not thoroughly resolved, and its species diversity in China is still debatable. In this study, we conducted an integrative taxonomic revision of Hedwigia in China based on both molecular and morphological evidence. We found an interesting species from Yunnan and Sichuan Province having an unknown combination of morphological characters. The molecular phylogenetic analyses based on mitochondrial nad5, chloroplast trnL-trnF and nuclear ITS markers suggest that this unknown moss represents a new species described here as H. sinica W.Z.Huang & R.L.Zhu, sp. nov. In addition, Hedwigia nemoralis Ignatova, Ignatov & Fedosov is proposed as a new synonym of H. filiformis (Michx.) P.Beauv. based on morphological and molecular evidence. Furthermore, H. czernyadjevae Ignatova, Ignatov & Fedosov, previously known only from Russia, is newly reported for China. The presence in China of H. stellata Hedenas and H. ciliata (Hedw.) Boucher is doubtful because the voucher specimens of these two species were re-identified as H. sinica and H. emodica or H. filiformis, respectively. In conclusion, at present, four species of Hedwigia are confirmed in China.