Zygomycetes are phylogenetically early diverging, ecologically diverse, industrially valuable, agriculturally beneficial, and clinically pathogenic fungi. Although new phyla and subphyla have been constantly established to accommodate specific members and a subkingdom Mucoromyceta, comprising Calcarisporiellomycota, Glomeromycota, Mortierellomycota and Mucoromycota, was erected to unite core zygomycetous fungi, phylogenetic relationships within phyla have not been well resolved. Taking account of the information of monophyly and divergence time estimated from ITS and LSU rDNA sequences, the present study updates the classification framework of the phylum Mucoromycota from the class down to the generic rank: three classes, three orders, 20 families (including five new families Circinellaceae, Protomycocladaceae, Rhizomucoraceae, Syzygitaceae and Thermomucoraceae) and 64 genera. The taxonomic hierarchy was calibrated with estimated divergence times: phylum earlier than 617 Mya, classes and orders earlier than 547 Mya, families earlier than 199 Mya, and genera earlier than 12 Mya. Along with this outline, all genera of Mucoromycota are annotated and 58 new species are described. In addition, three new combinations are proposed. In this study, we update the taxonomic backbone of the phylum Mucoromycota and reinforce its phylogeny. We also contribute numerous new taxa and enrich the diversity of Mucoromycota.

To elucidate the genomic traits of ecological diversification in the Hymenochaetales, we sequenced 15 new genomes, with attention to ectomycorrhizal (EcM) Coltricia species. Together with published data, 32 genomes, including 31 Hymenochaetales and one outgroup, were comparatively analyzed in total. Compared with those of parasitic and saprophytic members, EcM species have significantly reduced number of plant cell wall degrading enzyme genes, and expanded transposable elements, genome sizes, small secreted proteins, and secreted proteases. EcM species still retain some of secreted carbohydrate-active enzymes (CAZymes) and have lost the key secreted CAZymes to degrade lignin and cellulose, while possess a strong capacity to degrade a microbial cell wall containing chitin and peptidoglycan. There were no significant differences in secreted CAZymes between fungi growing on gymnosperms and angiosperms, suggesting that the secreted CAZymes in the Hymenochaetales evolved before differentiation of host trees into gymnosperms and angiosperms. Nevertheless, parasitic and saprophytic species of the Hymenochaetales are very similar in many genome features, which reflect their close phylogenetic relationships both being white rot fungi. Phylogenomic and molecular clock analyses showed that the EcM genus Coltricia formed a clade located at the base of the Hymenochaetaceae and divergence time later than saprophytic species. And Coltricia remains one to two genes of AA2 family. These indicate that the ancestors of Coltricia appear to have originated from saprophytic ancestor with the ability to cause a white rot. This study provides new genomic data for EcM species and insights into the ecological diversification within the Hymenochaetales based on comparative genomics and phylogenomics analyses.

Four new species within the genus Absidia, A. globospora, A. medulla, A. turgida, and A. zonata, are proposed based on a combination of morphological traits, physiological features, and molecular evidences. A. globospora is characterized by globose sporangiospores, a 1.0- to 3.5-μm-long papillary projection on columellae, and sympodial sporangiophores. A. medulla is characterized by cylindrical to oval sporangiospores, a 1.0- to 4.5-μm-long bacilliform projection on columellae, and spine-like rhizoids. A. turgida is characterized by variable sporangiospores, up to 9.5-μm-long clavate projections on columellae, and swollen top of the projection and inflated hyphae. A. zonata is characterized by cylindrical to oval sporangiospores, a 2.0- to 3.5-μm-long spinous projection on columellae, and as many as eight whorled sporangiophores. Phylogenetic analyses based on sequences of internal transcribed spacer rDNA and D1–D2 domains of LSU rDNA support the novelty of these four species within the Absidia. All new species are illustrated, and an identification key to all the known species of Absidia in China is included.

The species within the family Cunninghamellaceae are widely distributed and produce important metabolites. Morphological studies along with a molecular phylogeny based on the internal transcribed spacer (ITS) and large subunit (LSU) of ribosomal DNA revealed two new species in this family from soils in China, that is, Absidia ovalispora sp. nov. and Cunninghamella globospora sp. nov. The former is phylogenetically closely related to Absidia koreana, but morphologically differs in sporangiospores, sporangia, sporangiophores, columellae, collars, and rhizoids. The latter is phylogenetically closely related to Cunninghamella intermedia, but morphologically differs in sporangiola and colonies. They were described and illustrated.

Species of Absidia are distributed widely in the environment, while their diversity is insufficiently studied. Three new species, A. frigida, A. gemella and A. longissima, are proposed herein from Xinjiang and Yunnan in China based on phylogenetic, morphological and physiological evidence. According to maximum likelihood (ML), maximum parsimony (MP) and Bayesian inference (BI) analyses, the phylogenetical results suggest that A. frigida, A. gemella and A. longissima are closely related to A. psychrophilia, A. turgida and A. zonata and A. koreana, respectively, based on ITS and LSU rDNA sequences. Absidia frigida is characterized by a lower growth temperature, which does not grow above 24 °C. It differs from A. psychrophilia by sporangiophores, sporangia, columellae, collars and projections. Absidia gemella is distinguished from A. turgida by hypha, sporangiospores, sporangia, projections and sporangiophores. Absidia longissima is discriminated from A. zonata and A. koreana by sporangiophores, columellae and collars. The three new species are described and illustrated in this article.