*4.2. DNA Extraction, PCR, and Phylogenetic Reconstruction*

The genomic DNA was extracted using a Axygen Universal DNA Isolation Kit (Axygen, Suzhou, China). Partial 18S rDNA was obtained as described in Zhu et al. (2017). The PCR products were purified and then sent to Tsingke Biotech Company, Inc. (Wuhan, China) for sequencing. Additional 18S rDNA and *rbcL* sequences from Trentepohliales species were downloaded from GenBank for analyses. Sequence matrices for phylogenetic analysis were initially aligned with MAFFT 7.0 and refined manually using Seaview [26,27]. ModelFinder was utilized to select the best-fitting evolutionary models for each marker according to Bayesian information criterion calculations [28]. IQ-TREE and MrBayes3.2 were used to infer the phylogeny [29,30]. We performed two phylogenetic analyses using the 18S rDNA matrix. First, Cladophorales was used as the outgroup to infer the topology of Trentepohliales. Based upon the results of the first phylogenetic analysis, we selected *Cephaleuros* as the outgroup to perform the second analysis. In the phylogenetic analysis using the *rbc*L matrix, Ulotricales was selected as the outgroup.
