Campylosiphon (Burmanniaceae), a genus with two fully mycoheterotrophic species distributed in the tropics of South America and West Africa, is extended to two Asian species with “wingless” flowers. Specifically, Burmannia championii and B. densiflora, were transferred to Campylosiphon, and a Campylosiphon species new to science was described from Guizhou, China, supported by both morphological comparative analyses and molecular phylogeny inference. We revealed that the genus Campylosiphon can be characterized by five morphological aspects. With the revised circumscription, Campylosiphon becomes the third genus in Burmanniaceae with a pantropical distribution pattern. We also reported that two Campylosiphon species have advanced degraded plastomes and lost all protein-coding genes for photosynthesis.

ImageJ v1.53k (Schneide et al., 2012) was used to measure the length of perianth tube and pedicel of Burmannia aptera, B. championii, B. congesta and B. densiflora. Based on both the perianth tube and pedicel length, we classified these three lineages into seven groups, viz., (1) Burmannia aptera (two sheets of type specimen), (2) Burmannia congesta (four specimen sheets), (3) Burmannia densiflora (four specimen sheets), (4) B. championii (one collection and one photo recorded from Guangdong, China and type of Burmannia dalzielii Rendle (one specimen sheet) and types of B.championii (six specimen sheets), and type of Burmannia chionatha Schltr. (one specimen sheet)), (5) Burmannia tuberosa Becc. (two sheets of type specimens), (6) collections identified as B. championii recorded in Java, Indonesia (four specimen sheets) and (7) collections identified as B. championii recorded in the Western Ghats, India (two specimen sheets). The values of the aforementioned two morphological traits were then visualized using a simple scatter plot with marginal boxplot, and the classified seven groups were highlighted using a convex hull generated by “ggscatterhist” in R. Finally, statistic tests for differences in both the length of perianth tube and pedicel among the seven groups were conducted using pairwise Wilcoxon test in R.

DNA Extraction and Sequencing and Annotation—For phylogenetic analyses, 20 samples were newly sequenced, which consist of three individuals of Burmannia championii, one individual of Campylosiphon sp., one individual of Gymnosiphon usambaricum Blume, thirteen other Burmannia species and two Tacca species in this study. Total DNA of these samplings was extracted from silica-dried materials using a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany), following the manufacturer’s protocol. Next, paired-end sequencing was performed using Illumiana Hiseq 2000 platform, which generated up to 4 GB of raw data for each sample. Raw DNA data was assembled using GetOrganelle v1.6.2 (Jin et al., 2020) to assemble plastome, nrRNA and scaffolds of mitochondrial genome with proper parameters, respectively. Assembled plastomes were annotated by PGA.pl (Qu et al., 2019), and nrRNAs were annotated using Geneious v11.1.5 (Kearse et al., 2012) with the nrDNA annotation of Allium cepa (GenBank accession: KM117265) as reference, while scaffolds of mitochondrial were annotated by Geneious v11.1.5 using mitochondrial genes annotations of Burmannia species (Soto et al., 2020) and the nad1 b-c (mitochondrial gene intron) using Burmannia oblonga (GenBank accession: DQ786140) as references. All of these annotated sequences were submitted to GenBank, and GenBank accession numbers are exhibited in Appendix 1.