Effects of climate, distance, and a geographic barrier on ectomycorrhizal fungal communities in Japan: A comparison across Blakiston's Line

Scale-dependent influences of environmental, historical, and spatial processes on taxonomic and functional beta diversity of Japanese bat assemblages

This study investigated the relative influences of environmental, spatial, and historical factors, including the island-specific history of land connectivity, on bat assemblages in the Japanese Archipelago. We collected bat distribution data from 1408 studies and assigned them to Japan's First Standard Grid (approximately 6400 km2). Japanese bat assemblages were analyzed at two scales: the entire Japanese Archipelago comprised 16 islands and exclusively the four main islands. At first, we calculated taxonomic and functional total beta diversity (β total) by Jaccard pairwise dissimilarity and then divided this into turnover (β repl) and richness-difference (β rich) components. We conducted hierarchical clustering of taxonomic beta diversity to examine the influence of the two representative sea straits, Tsugaru and Tokara, which are considered biogeographical borders. Variation partitioning was conducted to evaluate the relative effects of the three factors on the beta diversity. Clustering revealed that the Tokara Strait bordered the two major clades; however, the Tsugaru Strait did not act as a biogeographical border for bats. In the variation partitioning, shared fraction between spatial and historical factors significantly explained taxonomic and functional β total and taxonomic β repl at the entire archipelago scale, but not at the four main islands scale extending only Tsugaru Strait but not Tokara Strait. Pure environmental factors significantly explained functional β total at both scales and taxonomic β total only at the four main islands scale. These results suggest that spatial and historical factors are more pronounced in biogeographical borders, primarily structuring assemblage composition at the entire archipelago scale, especially in taxonomic dimension. However, current environmental factors primarily shape the assemblage composition of Japanese bats at the main island scale. The difference in results between the two scales highlights that the primary processes governing assemblages of both dimensions depend on the quality of the dispersal barriers between terrestrial and aquatic barriers for bats.

A Contribution to Knowledge of Craterellus (Hydnaceae, Cantharellales) in China: Three New Taxa and Amended Descriptions of Two Previous Species

Species of Craterellus (Hydnaceae, Cantharellales) in China are investigated on the basis of morphological and molecular phylogenetic analyses of DNA sequences from nuc 28S rDNA D1-D2 domains (28S) and nuc rDNA internal transcribed spacer ITS1-5.8S-ITS2 region. Five species are recognized in China, of which three of them are described as new, viz. C. fulviceps, C. minor, and C. parvopullus, while two of them are previously described taxa, viz. C. aureus, and C. lutescens. A key to the known Chinese taxa of the genus is also provided.

Hemiaustroboletus, a new genus in the subfamily Austroboletoideae (Boletaceae, Boletales)

The present study describes Hemiaustroboletusgen. nov. in the subfamily Austroboletoideae (Boletaceae). Hemiaustroboletus is supported by morphological and molecular data using LSU and RPB2 regions. Additionally, its geographic distribution and intraspecific variation were inferred using ITS sequences. The genus is characterised by pileate-stipitate basidiomata; purple, brown, reddish-brown, orange-brown to dark brown vinaceous pileus; whitish or lilac to vinaceous context and a subclavate stipe. Microscopically, it is characterised by ornamented, slightly verrucose, cracked to perforated brown basidiospores. Two species are described within the genus, Hemiaustroboletus vinaceobrunneussp. nov. and H. vinaceussp. nov.Hemiaustroboletus vinaceussp. nov. is morphologically similar to Austroboletus gracilis, which suggests they may have been confused in the past. This study presents the phylogenetic placement, microscopic structures, detailed morphological descriptions and illustrations of both new species.

Phylogenetic placements and cultural characteristics of Tuber species isolated from ectomycorrhizas

Pure cultures of Tuber were isolated from ectomycorrhizal root tips in Abies sachalinensis plantations in Hokkaido, Japan. Their phylogenetic relationships as well as vegetative hyphal characteristics on culture media were reported. Phylogenetic analysis based on the internal transcribed spacer within ribosomal DNA settled well-supported eight lineages within Puberulum, Latisporum, and Maculatum clades in Tuber. Three and one lineages were grouped with undescribed species of Puberulum clade in Japan and that of the Latisporum group in China, respectively. Two lineages were closely associated to but distinct from an undescribed species of Puberulum clade in Japan. One lineage did not group with any sequences in the International Nucleotide Sequence Database (INSD), proposing a new taxon in the Latisporum group. One lineage was grouped with T. foetidum in Maculatum clade. All strains in each lineage displayed yellowish white, thin, filamentous colonies on Melin-Norkrans agar medium. Various differences in morphological characteristics of hyphae on pure cultures of various strains were noted, but they were frequently uncommon among strains of the same taxa. Isolation from ectomycorrhizal root tips can be among the effective ways to acquire pure cultures of Tuber strains.

Ectomycorrhizal fungal communities of secondary tropical forests dominated by Tristaniopsis in Bangka Island, Indonesia

In Southeast Asia, primary tropical rainforests are usually dominated by ectomycorrhizal (ECM) trees belonging to Dipterocarpaceae, although arbuscular mycorrhizal trees often outcompete them after disturbances such as forest fires and clear-cutting, thus preventing dipterocarp regeneration. In some secondary tropical forests, however, potentially ECM trees belonging to Tristaniopsis (Myrtaceae) become dominant and may help ECM dipterocarp forests to recover. However, we have no information about their mycorrhizal status in these settings. In this study, we analyzed ECM fungal communities in tropical secondary forests dominated by Tristaniopsis and investigated which ECM fungal species are shared with other tropical or temperate areas. In total, 100 samples were collected from four secondary forests dominated by Tristaniopsis on Bangka Island. ECM tips in the soil samples were subjected to molecular analyses to identify both ECM and host species. Based on a >97% ITS sequence similarity threshold, we identified 56 ECM fungal species dominated by Thelephoraceae, Russulaceae, and Clavulinaceae. Some of the ECM fungal species were shared between dominant Tristaniopsis and coexisting Eucalyptus or Quercus trees, including 5 common to ECM fungi recorded in a primary mixed dipterocarp forest at Lambir Hill, Malaysia. In contrast, no ECM fungal species were shared with other geographical regions, even with Tristaniopsis in New Caledonia. These results imply that secondary tropical forests dominated by Tristaniopsis harbor diverse ECM fungi, including those that inhabit primary dipterocarp forests in the same geographical region. They may function as refugia for ECM fungi, given that dipterocarp forests are disappearing quickly due to human activity.

Towards the conservation of ectomycorrhizal fungi on endangered trees: native fungal species on Pinus amamiana are rarely conserved in trees planted ex situ

Ectomycorrhizal (ECM) symbiosis is essential for the survival of both host trees and associated ECM fungi. However, during conservation activities of endangered tree species, their ECM symbionts are largely ignored. Here, we investigated ECM fungi in ex situ populations established for the conservation of Pinus amamiana, an endangered species distributed on Yakushima Island, Japan. Our objective was to determine whether ECM fungi in natural forests are conserved in ex situ populations on the same island. In particular, we focused on the existence of Rhizopogon yakushimensis, which is specific to P. amamiana and the most dominant in natural P. amamiana forests. Molecular identification of ECM fungi in resident tree roots and soil propagule banks indicated that ECM fungal species native to natural forests were rarely conserved in ex situ populations. Furthermore, R. yakushimensis was not confirmed in any of the resident root or spore bioassay samples from the ex situ populations. Thus, ECM fungal spores may not be effectively dispersed from natural forests located on the same island. Instead, ECM fungi distributed in other geographical regions occurred more frequently in the ex situ populations, indicating unintentional introductions of non-native ECM fungi from the nurseries where seedlings were raised before transplanting. These findings imply that the current ex situ conservation practices of endangered tree do not work for the conservation of native ECM fungi, and instead may need modification to avoid the risk of introducing non-native ECM fungi near the endangered forest sites.

Temperature niche position and breadth of ectomycorrhizal fungi: Reduced diversity under warming predicted by a nested community structure

Species with narrow niche breadths are assumed to be more susceptible to environmental changes than those with wide niche breadths. Although information on niche properties is necessary for predicting biological responses to environmental changes, such information is largely missing for soil microbes. In this study, we present the temperature niche positions and breadths of a functionally important group of eukaryotic soil microbes, ectomycorrhizal (EM) fungi. We compiled high-quality EM fungal sequence data from 26 forested sites in Japan (with mean annual temperatures ranging from 1.6 to 23.6°C) to create temperature niche profiles for each individual fungal species. Nested theory and a newly developed weighted-randomization null model were applied to 75 fungal operational taxonomic units (OTUs) with high occurrence records to examine potential preferences for certain temperature positions and breadths. Our analyses revealed that (a) many EM fungal OTUs were restricted to habitats with low mean annual temperatures, (b) fungal OTUs observed at colder sites exhibited narrower temperature breadths than expected by chance, (c) the composition of EM fungal OTUs exhibited a nested pattern along the temperature gradient, and (d) EM fungal richness was highest at colder sites, where the greatest degree of overlap in OTU occurrence was observed. These findings imply that future warming may limit the distribution of many EM fungal species that are currently adapted to only cold climates. This could eventually reduce EM fungal biodiversity, which is linked to forest function through symbiotic associations with trees. This study demonstrates the distribution and environmental ranges of various EM fungal species and can contribute to develop species distribution models with the aim of conserving microbes in the face of climate change.