Gang Wu

Mushrooms in the basidiomycete family Boletaceae are ecologically and economically very important. However, due to the morphological complexity and the limited phylogenetic information on the various species and genera of this fungal family, our understanding of its systematics and evolution remains rudimentary. In this study, DNA sequences of four genes (nrLSU, tef1-α, rpb1, and rpb2) were newly obtained from ca. 200 representative specimens of Boletaceae. Our phylogenetic analyses revealed seven major clades at the subfamily level, namely Austroboletoideae, Boletoideae, Chalciporoideae, Leccinoideae, Xerocomoideae, Zangioideae, and the Pulveroboletus Group. In addition, 59 genus-level clades were identified, of which 22 were uncovered for the first time. These 22 clades were mainly placed in Boletoideae and the Pulveroboletus Group. The results further indicated that the characters frequently used in the morphology-based taxonomy of Boletaceae, such as basidiospore ornamentation, the form of the basidioma, and the stuffed pores each had multiple origins within the family, suggesting that the use of such features for high-level classification of Boletaceae should be de-emphasized and combined with other characters.

In this paper, we provide a phylogenetic overview of Basidiomycota and related phyla in relation to ten years of DNA based phylogenetic studies since the AFTOL publications in 2007. We selected 529 species to address phylogenetic relationships of higher-level taxa using a maximum-likelihood framework and sequence data from six genes traditionally used in fungal molecular systematics (nrLSU, nrSSU, 5.8S, tef1-α, rpb1 and rpb2). These species represent 18 classes, 62 orders, 183 families, and 392 genera from the phyla Basidiomycota (including the newly recognized subphylum Wallemiomycotina) and Entorrhizomycota, and 13 species representing 13 classes of Ascomycota as outgroup taxa. We also conducted a molecular dating analysis based on these six genes for 116 species representing 17 classes and 54 orders of Basidiomycota and Entorrhizomycota. Finally we performed a phyloproteomics analysis from 109 Basidiomycota species and 6 outgroup taxa using amino-acid sequences retrieved from 396 orthologous genes. Recognition of higher taxa follows the criteria in Zhao et al (Fungal Divers 78:239–292, 2016): (i) taxa must be monophyletic and statistically well-supported in molecular dating analyses, (ii) their respective stem ages should be roughly equivalent, and (iii) stem ages of higher taxa must be older than those of lower level taxa. The time-tree indicates that the mean of stem ages of Basidiomycota and Entorrhizomycota are ca. 530 Ma; subphyla of Basidiomycota are 406–490 Ma; most classes are 358–393 Ma for those of Agaricomycotina and 245–356 Ma for those of Pucciniomycotina and Ustilaginomycotina; most orders of those subphyla split 120–290 Ma. Monophyly of most higher-level taxa of Basidiomycota are generally supported, especially those taxa introduced in the recent ten years: phylum Entorrhizomycota, classes Malasseziomycetes, Moniliellomycetes, Spiculogloeomycetes, Tritirachiomycetes and orders Amylocorticiales, Golubeviales, Holtermanniales, Jaapiales, Lepidostromatales, Robbauerales, Stereopsidales and Trichosporonales. However, the younger divergence times of Leucosporidiales (Microbotryomycetes) indicate that its order status is not supported, thus we propose combining it under Microbotryales. On the other hand, the families Buckleyzymaceae and Sakaguchiaceae (Cystobasidiomycetes) are raised to Buckleyzymales and Sakaguchiales due to their older divergence times. Cystofilobasidiales (Tremellomycetes) has an older divergence time and should be amended to a higher rank. We however, do not introduce it as new class here for Cystofilobasidiales, as DNA sequences from these taxa are not from their respective types and thus await further studies. Divergence times for Exobasidiomycetes, Cantharellales, Gomphales and Hysterangiales were obtained based on limited species sequences in molecular dating study. More comprehensive phylogenetic studies on those four taxa are needed in the future because our ML analysis based on wider sampling, shows they are not monophyletic groups. In general, the six-gene phylogenies are in agreement with the phyloproteomics tree except for the placements of Wallemiomycotina, orders Amylocorticiales, Auriculariales, Cantharellales, Geastrales, Sebacinales and Trechisporales from Agaricomycetes. These conflicting placements in the six-gene phylogeny vs the phyloproteomics tree are discussed. This leads to future perspectives for assessing gene orthology and problems in deciphering taxon ranks using divergence times.

Fungi of the family Boletaceae are of great importance in both ecology and economy. Our previous molecular phylogenetic studies have shown this family to have an extremely high species diversity in China. To further document the Chinese boletes, morphological studies and phylogenetic analyses were conducted including species of Boletaceae from China and other parts of the world. The results indicate that seven subfamily-level major clades and 62 generic clades can be retrieved, 52 of which are found in China. Furthermore, 100 species (comprising 32 genera) common in China are illustrated and described here in detail. Among them, four genera and 46 species are new to science, and 26 new combinations are proposed. To interpret the species concepts consistently, epitypes for five species are designated based on collections made from or near the type localities. Notes on eight extralimital species are also provided. Among the species reported here, most of the species are known only from East Asia. Only Leccinum scabrum (Bull.) Gray, Porphyrellus porphyrosporus (Fr. & Hök) E.-J. Gilbert and Tylopilus felleus (Bull.) P. Karst. are widely distributed in the Holarctic, and Buchwaldoboletus lignicola (Kallenb.) Pilát; Strobilomyces strobilaceus (Scop.) Berk. are in Eurasia; while Aureoboletus mirabilis (Murrill) Halling, Harrya chromapes (Frost) Halling et al., and Sutorius eximius (Peck) Halling et al. are found throughout East Asia-North America based on morphological and molecular phylogenetic evidences.

The wild gourmet mushroom Boletus edulis and its close allies are of significant ecological and economic importance. They are found throughout the Northern Hemisphere, but despite their ubiquity there are still many unresolved issues with regard to the taxonomy, systematics and biogeography of this group of mushrooms. Most phylogenetic studies of Boletus so far have characterized samples from North America and Europe and little information is available on samples from other areas, including the ecologically and geographically diverse regions of China. Here we analyzed DNA sequence variation in three gene markers from samples of these mushrooms from across China and compared our findings with those from other representative regions. Our results revealed fifteen novel phylogenetic species (about one-third of the known species) and a newly identified lineage represented by Boletus sp. HKAS71346 from tropical Asia. The phylogenetic analyses support eastern Asia as the center of diversity for the porcini sensu stricto clade. Within this clade, B. edulis is the only known holarctic species. The majority of the other phylogenetic species are geographically restricted in their distributions. Furthermore, molecular dating and geological evidence suggest that this group of mushrooms originated during the Eocene in eastern Asia, followed by dispersal to and subsequent speciation in other parts of Asia, Europe, and the Americas from the middle Miocene through the early Pliocene. In contrast to the ancient dispersal of porcini in the strict sense in the Northern Hemisphere, the occurrence of B. reticulatus and B. edulis sensu lato in the Southern Hemisphere was probably due to recent human-mediated introductions.