Xin-Yin Ma

The genus Bartramia, commonly known as “Apple Moss,” is characterized by its globose to subglobose capsules. However, the species diversity and distribution of the genus in China remain incompletely known due to the lack of a comprehensive taxonomic revision. In this study, we conducted a taxonomic revision of this genus in China, based on recent field collections and herbarium specimens. In total, 120 specimens from twelve provinces in China were examined. Bartramia deciduifolia is newly reported for China, where it occurs in Qinghai, Sichuan, Xizang, and Yunnan. Seven species are recognized in China: B. brevifolia, B. deciduifolia, B. halleriana, B. ithyphylla, B. laevisphaera, B. pomiformis, and B. subulata. Among them, B. laevisphaera is proposed as an endangered [EN B2ab(ii, iii)] species due to its small population and habitat, while the other six species are Least Concern (LC). Detailed morphological descriptions, color illustrations, and distributional information are provided, together with an updated identification key to the Chinese species.

Dicranum is one of the most diverse and widespread genera within the family Dicranaceae, encompassing ca. 110 accepted species worldwide. However, the taxonomy of this genus remains notoriously complex, with the circumscription of several species still unresolved, thereby limiting our understanding of the Dicranum’s diversity. During a recent survey of Dicranum in China, we found an intriguing species characterized by a unique combination of morphological traits including stiff and fragile leaves, sharply denticulate leaf apices, elongated, rectangular and porose laminal cells throughout, bistratose or partially bistratose laminal cells in the distal part, 1–2 stratose alar cells, and a transverse section of the costa in the lower portion of leaf with two stereid bands and undifferentiated epidermal layers. Morphological and molecular phylogenetic analyses, based on five chloroplast markers and one nuclear marker, support the recognition of this moss as a new species, which we described here as Dicranum motuoense sp. nov. Furthermore, we present the complete organellar genomes of this newly identified species. The chloroplast genome of D. motuoense is 123.94 kb in length, while the mitochondrial genome is 105.77 kb in length. A total of 127 genes and 66 genes were identified in the chloroplast and mitochondrial genomes, respectively. This study not only advances our understanding of species diversity with Dicranum but also contributes to the broader knowledge of its evolution. Additionally, a key for the identification of Dicranum species with fragile leaves is included.