Substrate specificity corresponds to distinct phylogenetic lineages: the case of Chaenotheca brunneola

We compared eight Chaenotheca specimens recently found to grow on fruit bodies of Trichaptum abietinwn and T fuscoviolaceum in Estonia with externally similar wood -dwelling Chaenotheca brunneola as well with another Trichaptum-inhabiting species, C. balsamconensis. We analysed their rDNA ITS sequences by means of phylogenetic analyses and five morpho-anatomical and pigmentation characters by cluster analysis. The obtained ten rDNA ITS sequences, including those from Chaenotheca balsamconensis, formed a supported Glade distinct from C. brunneola as well as from the rest of 18 analysed Chaenotheca species. The Trichaptum Glade included two lineages, of which one corresponded to Chaenotheca balsamconensis. According to cluster analysis, seven out of eight Chaenotheca specimens from Trichaptum formed a separate cluster. The morphological character that most differentiated wood inhabiting from Trichaptum-inhabiting specimens was the length of the stalks being somewhat shorter in the latter. Therefore, the Chaenotheca species externally similar to C. brunneola but growing on Trichaptum basidiomata form separate evolutionary lineage representing a case of convergent evolution and cryptic speciation.