Apostasia shenzhenica belongs to the subfamily Apostasioideae and is a primitive group located at the base of the Orchidaceae phylogenetic tree. However, the A. shenzhenica mitochondrial genome (mitogenome) is still unexplored, and the phylogenetic relationships between monocots mitogenomes remain unexplored. In this study, we discussed the genetic diversity of A. shenzhenica and the phylogenetic relationships within its monocotyledon mitogenome. We sequenced and assembled the complete mitogenome of A. shenzhenica, resulting in a circular mitochondrial draft of 672,872 bp, with an average read coverage of 122× and a GC content of 44.4%. A. shenzhenica mitogenome contained 36 protein-coding genes, 16 tRNAs, two rRNAs, and two copies of nad4L. Repeat sequence analysis revealed a large number of medium and small repeats, accounting for 1.28% of the mitogenome sequence. Selection pressure analysis indicated high mitogenome conservation in related species. RNA editing identified 416 sites in the protein-coding region. Furthermore, we found 44 chloroplast genomic DNA fragments that were transferred from the chloroplast to the mitogenome of A. shenzhenica, with five plastid-derived genes remaining intact in the mitogenome. Finally, the phylogenetic analysis of the mitogenomes from A. shenzhenica and 28 other monocots showed that the evolution and classification of most monocots were well determined. These findings enrich the genetic resources of orchids and provide valuable information on the taxonomic classification and molecular evolution of monocots.

The Elsholtzieae, comprising ca. 7 genera and 70 species, is a small tribe of Lamiaceae (mint family). Members of Elsholtzieae are of high medicinal, aromatic, culinary, and ornamentals value. Despite the rich diversity and value of Elsholtzieae, few molecular markers or plastomes are available for phylogenetics. In the present study, we employed high-throughput sequencing to assemble two Mosla plastomes, M. dianthera and M. scabra, for the first time, and compared with other plastomes of Elsholtzieae. The plastomes of Elsholtzieae exhibited a quadripartite structure, ranging in size from 148,288 bp to 152,602 bp. Excepting the absence of the pseudogene rps19 in Elsholtzia densa, the exhaustive tally revealed the presence of 132 genes (113 unique genes). Among these, 85 protein-coding genes (CDS), 37 tRNA genes, 8 rRNA genes, and 2 pseudogenes (rps19 and ycf1) were annotated. Comparative analyses showed that the plastomes of these species have minor variations at the gene level. Notably, the E. eriostchya plastid genome exhibited increased GC content regions in the LSC and SSC, resulting in an increased overall GC content of the entire plastid genome. The E. densa plastid genome displayed modified boundaries due to inverted repeat (IR) contraction. The sequences of CDS and intergenic regions (IGS) with elevated variability were identified as potential molecular markers for taxonomic inquiries within Elsholtzieae. Phylogenetic analysis indicated that four genera formed monophyletic entities, with Mosla and Perilla forming a sister clade. This clade was, in turn, sister to Collinsonia, collectively forming a sister group to Elsholtzia. Both CDS, and CDS + IGS could construct a phylogenetic tree with stronger support. These findings facilitate species identification and DNA barcoding investigations in Elsholtzieae and provide a foundation for further exploration and resource utilization within this tribe.

Vincetoxicum junzifengense from Fujian Province in Southeast China is described and illustrated. This new species is similar to V. versicolor and V. stauntonii, but it differs by its climber life form, pubescent lanceolate leaf, triangular corolla lobe, dentate corona lobe, and ovoid pollinium. Phylogenetic analysis using the nuclear (ITS) and three plastid (trnT-L, trnG and psbA-trnH) DNA sequences reveals that V. junzifengense is close to V. versicolor and V. yonakuniense.

Phyllagathis chongzuoensis, a new species from Guangxi Province, China, is described here. It is similar to P. erecta in having stiffly papery leaf blades with abaxially furfuraceous indumentum, similar leaf vernation, umbellate paniculate inflorescences and cup-shaped capsules, but differs in stoloniferous stem with indistinct internodes, shorter petioles, and obovate to suborbicular leaf blades with irregularly denticulate margin. Phylogenetic analyses based on nrITS and plastid genome confirmed that it is close to P. erecta.

A new orchid species, Bulbophyllum versicolor (Malaxideae, Epidendroideae, Orchidaceae), from Malipo, Yunnan, China, is described and illustrated here. Detailed morphological study indicates that B. versicolor is similar to B. japonicum, but it differs in the shape and size of leaf and flower and flower colour. Molecular analyses based on the nuclear ribosomal DNA (nrITS) and plastid DNA (matK, atpI-atpH and trnL-F) reveal that B. versicolor is a new species and genetically similar to B. japonicum.