Michaelmoelleria (Gesneriaceae), a new lithophilous dwelling genus and species with zigzag corolla tube from southern Vietnam

Michaelmoelleria, a new genus from southern Vietnam is described with a single species, M. vietnamensis. The new genus is morphologically most similar to Deinostigma and Tribounia but it differs from the latter two by having four fertile stamens. Nuclear ribosomal internal transcribed spacer (ITS) region and plastid trnL-F intron spacer (trnL-F) DNA sequence data from the new genus and eighty-seven species representing 42 genera within tribe Didymocarpeae are used to resolve its generic placement. The molecular evidence reveals that it is most closely related to Cathayanthe rather than Deinostigma and Tribounia. The chromosome number is counted as 2n = 36 that further clarified its distinction comparing to the related genera within tribe Didymocarpeae. A global conservation assessment is also performed and classifies Michaelmoelleria vietnamensis as Critically Endangered (CR).