Abstract
The genus Calyptothecium, currently comprising ca. 30 species worldwide, is the largest genus within the family Pterobryaceae. However, a comprehensive taxonomic revision of this genus is lacking. Calyptothecium philippinense Broth. 1899, a moss species widely found in the tropical regions of Asia, is characterized by the unique rugose leaves and large auriculate leaf bases. In this study, we sequenced the complete chloroplast genome (CPG) of C. philippinense using the Illumina NovaSeq 6000 platform. The length of the CPG of C. philippinense was determined to be 124,513 bp, with an AT content of 74%. The CPG of C. philippinense exhibited a standard quadripartite structure, consisting of one small single-copy (SSC) region (18,541 bp), one large single-copy region (LSC) (87,222 bp), and two inverted repeat (IR) regions (9375 bp each). A total of 126 genes from the CPG of C. philippinense were annotated, including 82 protein-coding genes, eight ribosomal RNA genes, and 36 transfer RNA genes. Phylogenetic analysis based on the CPGs of 25 bryophyte taxa revealed that the three Pterobryaceae species C. philippinense, Calyptothecium hookeri (Mitt.) Broth. and Pterobryopsis orientalis (Müll. Hal.) M. Fleisch. formed a robust clade. The findings could facilitate more accurate classification and help elucidate evolutionary relationships within Calyptothecium.