A phylogenetic assessment of a fungicolous lineage in Coniocybomycetes: Chaenotricha, a new genus of Trichaptum-inhabiting species.

The globally distributed genus Trichaptum is one of the most species-rich among polypores in terms of hosting other fungi. Among Trichaptum-associates, there is a group of mazaediate lichenized fungi (Coniocybomycetes, Ascomycota) that previously had an uncertain phylogenetic position. DNA sequences - mitochondrial small subunit (mtSSU), nuclear large subunit rDNA (nuLSU), and internal transcribed spacer (ITS) - were obtained from 29 specimens collected from Europe and North America. Maximum likelihood and Bayesian inference analyses of these three gene loci were used to infer phylogenetic position and relationships among lineages. Statistical tests were used to find which phenotypical characteristics distinguish species. The molecular sequence data provide evidence that the fungicolous specimens form a distinct lineage within Coniocybomycetes sister to the combined clade of Chaenotheca s. lat. and Sclerophora. Considering its phylogenetic placement and strict specialization, we describe a new genus - Chaenotricha. This fungicolous lineage contains three species based on molecular characteristics. Morphological characters mostly overlap except for spore size and stalk length of apothecia. We provide a new combination, Chaenotricha obscura, for the only previously described species for which we designate an epitype, and introduce a new species - Chaenotricha cilians. The third lineage remains undescribed because of a small sample size, which did not allow us to clearly delineate species boundaries. Citation: Suija A, McMullin RT, Lõhmus P (2023). A phylogenetic assessment of a fungicolous lineage in Coniocybomycetes: Chaenotricha, a new genus of Trichaptum-inhabiting species. Fungal Systematics and Evolution 12: 255-269. doi: 10.3114/fuse.2023.12.13.