Revision of Campylosiphon Benth. (Burmanniaceae), with new combinations and a new species described

<p><em>Campylosiphon</em> (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, <em>Burmannia championii and B. densiflora</em>, were transferred to <em>Campylosiphon</em>, and a <em>Campylosiphon</em> species new to science was described from Guizhou, China, supported by both morphological comparative analyses and molecular phylogeny inference. We revealed that the genus <em>Campylosiphon</em> can be characterized by five morphological aspects. With the revised circumscription, <em>Campylosiphon</em> becomes the third genus in Burmanniaceae with a pantropical distribution pattern. We also reported that two <em>Campylosiphon</em> species have advanced degraded plastomes and lost all protein-coding genes for photosynthesis.</p>