Phylogenetic and morphological re-evaluation of Camptophora

Abstract

Abstract The generic variety and habitats of Camptophora species, generally known as black yeasts have not been clarified. Here, we re-evaluated Camptophora based on morphological observations and phylogenetic analyses. Because investigations on Camptophora relied only on a few strains/specimens, twenty-four Camptophora-related strains were newly obtained from 13 leaf samples from various plant species to redefine the generic and species concepts of Camptophora. Their molecular phylogenetic relationships were examined based on the small subunit nuclear ribosomal DNA (nSSU, 18S rDNA), internal transcribed spacer rDNA operon (ITS), large subunit nuclear ribosomal DNA (LSU, 28S rDNA), β-tubulin (tub), the second largest subunit of RNA polymerase II (rpb2), and mitochondrial small subunit DNA (mtSSU). Single- and multi-locus analyses using SSU-ITS-LSU-rpb2-mtSSU revealed a robust phylogenetic relationship among Camptophora within the Chaetothyriaceae. Camptophora can be distinguished from other chaetothyriaceous genera by its snake-shaped conidia with microcyclic conidiation and loosely interwoven mycelial masses. Based on the results of the phylogenetic analyses, two undescribed lineages were recognised, and Ca. schimae was considered to be excluded from the genus. ITS sequence comparison with environmental DNA (eDNA) sequences revealed the distribution of the genus limited to the Asia-Pacific region. Camptophora has been isolated or detected from abrupt sources, and the reason for this was inferred to be their microcycle. Mechanisms driving genetic diversity within species are discussed with respect to their phyllosphere habitats.