Zai-Wei Ge

High diversity and widespread occurrence of mitotic spore mats in ectomycorrhizal Pezizales

Fungal mitospores may function as dispersal units and/ or spermatia and thus play a role in distribution and/or mating of species that produce them. Mitospore production in ectomycorrhizal (EcM) Pezizales is rarely reported, but here we document mitospore production by a high diversity of EcM Pezizales on three continents, in both hemispheres. We sequenced the internal transcribed spacer (ITS) and partial large subunit (LSU) nuclear rDNA from 292 spore mats (visible mitospore clumps) collected in Argentina, Chile, China, Mexico and the USA between 2009 and 2012. We collated spore mat ITS sequences with 105 fruit body and 47 EcM root sequences to generate operational taxonomic units (OTUs). Phylogenetic inferences were made through analyses of both molecular data sets. A total of 48 OTUs from spore mats represented six independent EcM Pezizales lineages and included truffles and cup fungi. Three clades of seven OTUs have no known meiospore stage. Mitospores failed to germinate on sterile media, or form ectomycorrhizas on Quercus, Pinus and Populus seedlings, consistent with a hypothesized role of spermatia. The broad geographic range, high frequency and phylogenetic diversity of spore mats produced by EcM Pezizales suggests that a mitospore stage is important for many species in this group in terms of mating, reproduction and/or dispersal.

The genus Macrolepiota (Agaricaceae, Basidiomycota) in China

Species of the genus Macrolepiota (Agaricaceae) in China were investigated on the basis of morphology and DNA sequences data. Six species, i.e., M. detersa, M. dolichaula, M. mastoidea, M. orientiexcoriata, M. procera, and M. velosa are recognized, of which M. detersa and M. orientiexcoriata are new species. All of them are described and illustrated with line drawings, and a key is provided to those recognized species. The taxonomic uncertainty of M. crustosa, originally described from China, is also discussed. ITS sequences were used to support the new species delimitations and to test the conspecificity between the Chinese specimens and their relatives from other continents. Phylogenetic analyses identify three clades within Macrolepiota: /macrolepiota, /macrosporae, and /volvatae clade. /macrolepiota clade and /macrosporae clade respectively correspond to section Macrolepiota and section Macrosporae in Bon’s infrageneric classification. Section Volvatae is proposed to accommodate species with a volva but without clamp connections within Macrolepiota.

The genus Macrolepiota (Agaricaceae, Basidiomycota) in China - eScholarship

Species of the genus Macrolepiota (Agaricaceae) in China were investigated on the basis of morphology and DNA sequences data. Six species, i.e., M. detersa, M. dolichaula, M. mastoidea, M. orientiexcoriata, M. procera, and M. velosa are recognized, of which M. detersa and M. orientiexcoriata are new species. All of them are described and illustrated with line drawings, and a key is provided to those recognized species. The taxonomic uncertainty of M. crustosa, originally described from China, is also discussed. ITS sequences were used to support the new species delimitations and to test the conspecificity between the Chinese specimens and their relatives from other continents. Phylogenetic analyses identify three clades within Macrolepiota: /macrolepiota, /macrosporae, and /volvatae clade. /macrolepiota clade and /macrosporae clade respectively correspond to section Macrolepiota and section Macrosporae in Bon’s infrageneric classification. Section Volvatae is proposed to accommodate species with a volva but without clamp connections within Macrolepiota.

Phylogenetic analysis of rDNA sequences indicates that the sequestrate Amogaster viridiglebus is derived from within the agaricoid genus Lepiota (Agaricaceae)

The rare sequestrate fungus Amogaster viridiglebus is known from only one collection in California where it was discovered among Populus roots. Based on sporocarp coloration and spore morphology, this sequestrate taxon was putatively considered to be an ectomycorrhizal member of the Boletales. However, no molecular data were previously available to definitively determine the closest relatives of this fungus. Here we revisit the morphology of Amogaster viridiglebus and present a phylogenetic analysis based on ITS and 28S ribosomal DNA. Our phylogeny indicates that Amogaster viridiglebus is nested in the genus Lepiota, suggesting that this rare species has a saprobic trophic mode and does not form ectomycorrhizae with plants. A new combination, L. viridigleba, is made based on these phylogenetic results.

Multigene Molecular Phylogeny and Biogeographic Diversification of the Earth Tongue Fungi in the Genera Cudonia and Spathularia (Rhytismatales, Ascomycota)

The family Cudoniaceae (Rhytismatales, Ascomycota) was erected to accommodate the “earth tongue fungi” in the genera Cudonia and Spathularia. There have been no recent taxonomic studies of these genera, and the evolutionary relationships within and among these fungi are largely unknown. Here we explore the molecular phylogenetic relationships within Cudonia and Spathularia using maximum likelihood and Bayesian inference analyses based on 111 collections from across the Northern Hemisphere. Phylogenies based on the combined data from ITS, nrLSU, rpb2 and tef-1α sequences support the monophyly of three main clades, the /flavida, /velutipes, and /cudonia clades. The genus Cudonia and the family Cudoniaceae are supported as monophyletic groups, while the genus Spathularia is not monophyletic. Although Cudoniaceae is monophyletic, our analyses agree with previous studies that this family is nested within the Rhytismataceae. Our phylogenetic analyses circumscribes 32 species-level clades, including the putative recognition of 23 undescribed phylogenetic species. Our molecular phylogeny also revealed an unexpectedly high species diversity of Cudonia and Spathularia in eastern Asia, with 16 (out of 21) species-level clades of Cudonia and 8 (out of 11) species-level clades of Spathularia. We estimate that the divergence time of the Cudoniaceae was in the Paleogene approximately 28 Million years ago (Mya) and that the ancestral area for this group of fungi was in Eastern Asia based on the current data. We hypothesize that the large-scale geological and climatic events in Oligocene (e.g. the global cooling and the uplift of the Tibetan plateau) may have triggered evolutionary radiations in this group of fungi in East Asia. This work provides a foundation for future studies on the phylogeny, diversity, and evolution of Cudonia and Spathularia and highlights the need for more molecular studies on collections from Europe and North America.

New Asian species of the genus Anamika (euagarics, hebelomatoid clade) based on morphology and ribosomal DNA sequences

Two dark-spored agaric species from Asia are placed in the genus Anamika (Agaricales or euagarics clade). This result is supported by ITS and nLSU-rDNA sequences with strong measures of branch support, in addition to several morphological and ecological similarities. An inclusive ITS study was performed using a mixed model Bayesian analysis that suggests the derived status of Anamika within Hebeloma, thereby rendering Hebeloma a paraphyletic genus. However, the monophyly of Hebeloma cannot be rejected outright given ITS and nLSU-rDNA data. Thus, we propose two new Asian species in Anamika: A. angustilamellata sp. nov. from dipterocarp and fagaceous forests of southwestern China and northern Thailand; and A. lactariolens comb. nov., a Japanese species originally described in the genus Alnicola. A complete description of A. angustilamellata, including illustrations, is provided.

Two new unusual Leucoagaricus species (Agaricaceae) from tropical China with blue-green staining reactions

Most species of the genus Leucoagaricus have been described from temperate regions in North America and Europe, but little is known about the genus from tropical areas. In this report we describe two new species of Leucoagaricus, namely La. flavovirens and La. atroazureus, from tropical China. The two species are characterized by turning blue-green or dark blue where bruised and by unique phylogenetic placement. Two new combinations, namely La. viriditinctus and La. caerulescens, are proposed. The neotype of La. viridiflavus from India was found to differ from La. flavovirens based on morphology and ITS sequence comparison. A monophyletic group of four bluing species from Old World tropics is recovered but with poor measures of branch support.

Evolutionary history of the sequestrate genus Rossbeevera (Boletaceae) reveals a new genus Turmalinea and highlights the utility of ITS minisatellite-like insertions for molecular identification

The sequestrate (truffle-like) basidiomycete genera Rossbeevera, Chamonixia, and Octaviania are closely related to the epigeous mushroom genera Leccinum and Leccinellum. In order to elucidate the properties and placement of several undescribed sequestrate taxa in the group and to reveal the evolutionary history of Rossbeevera and its allies, we conducted phylogenetic analyses based on three nuclear (ITS, nLSU, EF-1α) and two mitochondrial DNA loci (ATP6 and mtSSU) as well as precise morphological observations. Phylogenetic analyses of three nuclear loci suggest a complex evolutionary history with sequestrate fruiting bodies present in several clades, including a previously unrecognized sister clade to Rossbeevera. Here we propose a new sequestrate genus, Turmalinea, with four new species and one new subspecies as well as two new species of Rossbeevera. The three-locus nuclear phylogeny resolves species-level divergence within the Rossbeevera-Turmalinea lineage, whereas a separate phylogeny based on two mitochondrial genes corresponds to geographic distance within each species-level lineage and suggests incomplete lineage sorting (ILS) and gene introgression within several intraspecific lineages of Rossbeevera. Furthermore, topological incongruence among the three nuclear single-locus phylogenies suggests that ancient speciation within Rossbeevera probably involved considerable ILS. We also found an unusually long, minisatellite-like insertion within the ITS2 in all Rossbeevera and Turmalinea species. A barcode gap analysis demonstrates that the insertion is more informative for discrimination at various taxonomic levels than the rest of the ITS region and could therefore serve as a unique molecular barcode for these genera.

Soil pH and mineral nutrients strongly influence truffles and other ectomycorrhizal fungi associated with commercial pecans (Carya illinoinensis)

Background and aimsPecan truffles (Tuber lyonii) have high commercial value and the potential to be produced in a dual-cropping system with pecan. However, little is known about the linkages among ectomycorrhizal (ECM) fungal diversity, community structure, and environmental factors in pecan orchard ecosystems. Our aim is to investigate how soil pH and other edaphic factors influence the richness and composition of ECM fungi.MethodsWe characterized the soil factors and ECM fungal community associated with pecan and adjacent native trees with 454 pyrosequencing at a regional scale, and tested whether the effects of pH and soil factors altered the ECM fungal communities.ResultsOverall ECM fungal diversity associated with pecan trees was high and about a third of all taxa were shared with native trees adjacent to orchards. The community structure was correlated significantly with soil variables including K, Ca, Mg, Mn, P, Zn and soil pH, but not organic matter. Soil pH was positively correlated with species diversity in the /tuber-helvella, /galactinia, /pachyphloeus-amylascus, and /pisolithus-scleroderma lineages.ConclusionspH and soil factors play a key role in regulating the ECM fungal communities in pecan orchards. The frequency and abundance of the pecan truffle and related species is positively and significantly correlated with higher soil pH.

Four new species in Leucoagaricus (Agaricaceae, Basidiomycota) from Asia.

The genus Leucoagaricus has been well studied in Europe. However, species diversity of Leucoagaricus in Asia remains poorly known, especially in the mountains of southwestern China, a hot spot for biodiversity. Based on morphological characters and molecular data, four new species are described, La. asiaticus, La. subcrystallifer, La. subpurpureolilacinus and La. truncatus. Detailed morphological descriptions, drawings of microstructures for novel taxa and comparisons with closely allied taxa are provided. Phylogenetic analyses inferred from internal transcribed spacer (ITS) and region 6–7 of the gene for the second largest subunit of RNA polymerase II (rpb2) sequences show that the novel taxa are nested within a well-supported clade jointly formed by members of Leucoagaricus section Rubrotincti and subgenus Sericeomyces.