Integrative Morphological and Molecular Insights into Rhynchostegium celebicum (Brachytheciaceae), a moss from the Eastern Himalaya

This study provides a detailed morphological, ultrastructural, and phylogenetic analysis of the moss Rhynchostegium celebicum (Brachytheciaceae), from Darjeeling Hills, a key region within the Eastern Himalayan biodiversity hotspot. Scanning Electron Microscopy (SEM) was the first to document the sporophytic ultrastructure, revealing fine papillose spores and distinct ornamentation on the peristome teeth, indicating differential hygroscopic roles. Molecular phylogenetic analysis employing the plastid rbcL sequence strongly supported a monophyletic Rhynchostegium clade and showed a close relationship between R. celebicum and R. megapolitanum . This study substantiates the identity and phylogenetic placement of the species, providing essential insights into the biogeographic distribution and evolutionary relationships within Rhynchostegium in the region.