Ignatovia U.B.Deshmukh (Leskeaceae, Bryophyta), a monospecific genus endemic to Russia, newly found in Beijing, China with special references to its complete organelle genomes

The genus Ignatovia U.B.Deshmukh comprises the sole species Ignatovia microphylla (Ignatov & Ignatova) U.B.Deshmukh, which has been thus far known only from Russia. During our recent expeditions to Shangfangshan National Forest Park in Beijing, China, we encountered an interesting moss that can be assignable to I. microphylla, characterized by small leaves, round to oblate and thick-walled lamina cells that are somewhat bulging abaxially, nearly homogeneous thick-walled cells in the cross-section of the stem, a cross-section of the costa without stereids, and triangular inner perichaetial leaves. Molecular phylogenetic analyses based on nrITS1-5.8S-ITS2 and trnL-F further support the morphological identification. Our finding represents the first report of I. microphylla outside Russia, a new generic record for China. Additionally, we assembled and annotated its organelle genomes. The results showed that the complete chloroplast genome is 124 918 base pairs (bp) in length with 29.2% GC content, consisting of 82 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The complete mitogenome is 103 161 bp in length with a GC content of 41.0%, comprising 40 protein-coding genes, 24 tRNA genes, and three rRNA genes. The discovery of I. microphylla could lay the foundation for investigating biogeographical patterns and species evolution in further studies.