Novel Metschnikowia yeasts from the gut of green lacewing in Japan.

Family Chrysopidae is known to harbor specific gut yeasts. However, no studies have been conducted outside of a limited number of these green lacewing species, and the diversity of yeasts in the family as a whole is not known. Therefore, we collected 58 Chrysopidae adults (9 species, 6 genera, 2 subfamilies) in Japan and isolated yeasts from all individuals. The results showed for the first time that not only subfamily Chrysopinae but also subfamily Apochrysinae have gut yeasts. We obtained 58 yeast isolates (one from each host individual), all of which were of the genus Metschnikowia. 28S rDNA- and ITS-based phylogenetic analysis showed that the isolates were divided into three clades, designated clade I, II, and III. Clade I contains two previously described Chrysopidae gut yeasts (M. picachoensis and M. pimensis) as well as a one of our new species named M. shishimaru. Clade II is a new clade, with at least two new species named M. kenjo and M. seizan. Clade III contains the previously described species M. noctiluminum, a Chrysopidae gut yeast, and one of our isolate (We have not described it as new species). However, the phylogenetic relationship between our isolate and M. noctiluminum was unclear. These results indicate that the Japanese Chrysopidae gut yeasts consist mainly of three undescribed species and that they are more unique than those found in previous surveys. The results of this study indicate that Chrysopidae gut yeasts are more diverse than previously thought and should be investigated in various geographical regions in the future.

Re-examination of a rare protosteloid amoeba Schizoplasmodiopsis micropunctata, and the revision of Tychosporium (Cavosteliida, Variosea, Amoebozoa).

The genus Schizoplasmodiopsis is one of the most morphologically diverse groups among the class Variosea. Recent phylogenetic studies suggest that Schizoplasmodiopsis is polyphyletic, but there are few taxonomic studies of this genus. We established S. micropunctata strain YIP-40, observed in detail its of morphology and lifecycle, and conducted a phylogenetic analysis. The phylogenetic analysis revealed that S. micropunctata was sister to Tychosporium acutostipes. Scanning electron microscopy showed S. micropunctata had a non-deciduous hilum structure that is unique to Tychosporium. The morphology of amoebae, mitotic behavior, and prespore cells of S. micropunctata also supported the close relationship to Tychosporium. We propose to transfer S. micropunctata to Tychosporium and emend the generic concept of Tychosporium to include this species.

Shortened lifespan induced by a high-glucose diet is associated with intestinal immune dysfunction in Drosophila sechellia.

Organisms can generally be divided into two nutritional groups: generalists that consume various types of food and specialists that consume specific types of food. However, it remains unclear how specialists adapt to only limited nutritional conditions in nature. In this study, we addressed this question by focusing on Drosophila fruit flies. The generalist Drosophila melanogaster can consume a wide variety of foods that contain high glucose levels. In contrast, the specialist Drosophila sechellia consumes only the Indian mulberry, known as noni (Morinda citrifolia), which contains relatively little glucose. We showed that the lifespan of D. sechellia was significantly shortened under a high-glucose diet, but this effect was not observed for D. melanogaster. In D. sechellia, a high-glucose diet induced disorganization of the gut epithelia and visceral muscles, which was associated with abnormal digestion and constipation. RNA-sequencing analysis revealed that many immune-responsive genes were suppressed in the gut of D. sechellia fed a high-glucose diet compared with those fed a control diet. Consistent with this difference in the expression of immune-responsive genes, high glucose-induced phenotypes were restored by the addition of tetracycline or scopoletin, a major nutritional component of noni, each of which suppresses gut bacterial growth. We propose that, in D. sechellia, a high-glucose diet impairs gut immune function, which leads to a change in gut microbiota, disorganization of the gut epithelial structure and a shortened lifespan.

Taxonomic study of polymorphic basidiomycetous fungi Sirobasidium and Sirotrema: Sirobasidium apiculatum sp. nov., Phaeotremella translucens comb. nov. and rediscovery of Sirobasidium japonicum in Japan.

Species in the genera Sirobasidium and Sirotrema (Tremellales, Tremellomycetes, Agaricomycotina, Basidiomycota) have been described based solely on the morphology of teleomorph, and many of them lack both isolates of anamorphic yeast state and nucleotide sequence data. Strains of Sirotrema translucens and Sirobasidium japonicum were established for the first time from basidiocarps collected in Japan. Also, an undescribed species in the genus Sirobasidium was isolated. Sirobasidium sp. was characterized by its apiculate epibasidia and 2-celled basidia divided by a longitudinal septum, which is a unique combination of characteristics in the genus. Although the phylogenetic placement of Sb. japonicum within the Tremellales was not resolved in our analysis, Sirobasidium sp. formed a well-supported monophyletic clade with Sb. magnum and Fibulobasidium spp., and Sirotrema translucens was located in the genus Phaeotremella. Mating experiments using single-basidiospore strains showed that Sb. japonicum produced basidia, epibasidia, and basidiospores on a nutrient-poor medium, and the life cycle was successfully completed in controlled conditions. In conclusion, we propose Sirobasidium apiculatum sp. nov. and Phaeotremella translucens comb. nov.

Four Pristionchus species associated with two mass-occurring Parafontaria laminata populations.

Phoretic nematodes associated with two mass-occurring populations of the millipede Parafontaria laminata were examined, focusing on Pristionchus spp. The nematodes that propagated on dissected millipedes were genotyped using the D2-D3 expansion segments of the 28S ribosomal RNA gene. Four Pristionchus spp. were detected: P. degawai, P. laevicollis, P. fukushimae, and P. entomophagus. Of the four, P. degawai dominated and it was isolated from more than 90% of the millipedes examined. The haplotypes of partial sequences of mitochondrial cytochrome oxidase subunit I examined for Pristionchus spp. and P. degawai showed high haplotype diversity.

Dual colonization of Mucoromycotina and Glomeromycotina fungi in the basal liverwort, Haplomitrium mnioides (Haplomitriopsida).

In general, Glomeromycotina was thought to be the earliest fungi forming mycorrhiza-like structure (MLS) in land plant evolution. In contrast, because the earliest divergent lineage of extant land plants, i.e. Haplomitriopsida liverworts, associates only with Mucoromycotina mycobionts, recent studies suggested that those fungi are novel candidates for the earliest mycobionts. Therefore, Mucoromycotina-Haplomitriopsida association currently attracts attention as an ancient mycorrhiza-like association. However, mycobionts were identified in only 7 of 16 Haplomitriopsida species and the mycobionts diversity of this lineage is largely unclarified. To clarify the taxonomic composition of mycobionts in Haplomitriopsida, we observed MLSs in the rhizome of Haplomitrium mnioides (Haplomitriopsida), the Asian representative Haplomitriopsida species, and conducted molecular identification of mycobionts. It was recorded for the first time that Glomeromycotina and Mucoromycotina co-occur in Haplomitriopsida as mycobionts. Significantly, the arbuscule-like branching (ALB) of Glomeromycotina was newly described. As the Mucoromycotina fungi forming MLSs in H. mnioides, Endogonaceae and Densosporaceae were detected, in which size differences of hyphal swelling (HS) were found between the fungal families. This study provides a novel evidence in the MLS of Haplomitriopsida, i.e. the existence of Glomeromycotina association as well as the dominant Mucoromycotina association. In addition, since hyphal characteristics of the HS-type MLS were quite similar to those of fine endophytes (FE) of Endogonales in other bryophytes and vascular plants previously described, this MLS is suggested to be included in FE. These results suggest that Glomeromycotina and Mucoromycotina were acquired concurrently as the mycobionts by the earliest land plants evolved into arbuscular mycorrhizae and FE. Therefore, dual association of Haplomitriopsida, with Endogonales and Glomeromycotina will provide us novel insight on how the earliest land plants adapted to terrestrial habitats with fungi.

Phylogenetic Position of Parasitic Chytrids on Diatoms: Characterization of a Novel Clade in Chytridiomycota.

Chytrids are true fungi that reproduce with posteriorly uniflagellate zoospores. In the last decade, environmental DNA surveys revealed a large number of uncultured chytrids as well as undescribed order-level novel clades in Chytridiomycota. Although many species have been morphologically described, only some DNA sequence data of parasitic chytrids are available from the database. We herein discuss five cultures of parasitic chytrids on diatoms Aulacoseira spp. and Asterionella formosa. In order to identify the chytrids examined, thallus morphologies were observed using light microscopy. We also conducted a phylogenetic analysis using 18S, 5.8S, and 28S rDNA sequences to obtain their phylogenetic positions. Based on their morphological characteristics, two cultures parasitic on As. formosa were identified as Rhizophydium planktonicum and Zygorhizidium planktonicum. The other three cultures infecting Aulacoseira spp. (two on Aulacoseira ambigua and the other on Aulacoseira granulata) were regarded as Zygorhizidium aff. melosirae. The results of the molecular phylogenetic analysis revealed that R. planktonicum belonged to the known order Chytridiales, while the two species of Zygorhizidium were placed in a novel clade that was previously reported as an undescribed clade composed of only the environmental sequences of uncultured chytrids.

First detection of Endogone ectomycorrhizas in natural oak forests.

The order Endogonales in Mucoromycotina, an early divergent lineage of fungi, includes ectomycorrhizal (EM) fungi. This order is therefore considered a key taxon for elucidation of the evolution of EM associations. Recent studies have revealed high diversity of EM lineages of Basidiomycota and Ascomycota; however, EM associations of Endogonales and its relatives remain largely unknown. In this study, EM root tips with a unique fungal sheath, with aseptate and highly branched hyphae of variable widths, were identified in Quercus acutissima and Quercus crispula forests in the temperate zone of Japan. The mycobionts were confirmed as Endogone sp., which were placed as a sister clade of Endogone pisiformis, based on phylogenetic analyses of the small and large subunits of the nuclear ribosomal RNA and elongation factor-1α genes. This is the first report of EM of Endogone in natural forests of the Northern Hemisphere and the first finding on Quercus.

Cyclopsomyces plurioperculatus: a new genus and species of Lobulomycetales (Chytridiomycota, Chytridiomycetes) from Japan.

Lobulomycetales is one of the smallest orders of Chytridiomycota, containing only four genera and five species. In a survey in Japan we isolated a chytrid from a soil sample collected in a broadleaf forest, which grouped in Lobulomycetales by BLAST query. To identify this chytrid and determine its taxonomic position, thallus development and morphology were observed by light microscopy and zoospore ultrastructure was examined using a transmission electron microscopy. We conducted a phylogenetic analysis using nuc 28S rDNA sequences. Thallus morphology was characterized by a spherical zoosporangium with multiple operculate discharge papillae, which is different from that of any other species in Lobulomycetales. This chytrid is similar to Chytriomyces multioperculatus in having multiple operculate discharge papillae, but these are distinguished by characters of the discharge papillae and rhizoidal systems. Zoospores of this chytrid had electron-dense material in the kinetosome, a unique character in the order. Our 28S phylogeny placed it in a distinct clade, sister to all described species in Lobulomycetaceae. Based on these results, we propose a new genus and species of Lobulomycetales, Cyclopsomyces plurioperculatus.

First record of Stigmatomyces (Ascomycota: Laboulbeniales) on Drosophilidae from Japan.

Three Stigmatomyces species were detected on five drosophilid species from Japan. We report Stigmatomyces majewskii on Drosophila rufa and Drosophila suzukii, Stigmatomyces scaptodrosophilae on Scaptodrosophila coracina and Scaptodrosophila subtilis, and Stigmatomyces sacaptomyzae on Scaptomyza graminum. Except for Scaptomyza graminum, each of these species is a newly identified Stigmatomyces host. Our discovery that D. suzukii is a host of S. majewskii may provide new pest management approaches for this global agricultural pest insect.

Detection and isolation of a new member of Burkholderiaceae-related endofungal bacteria from Saksenaea boninensis sp. nov., a new thermotolerant fungus in Mucorales.

Thermotolerance in Mucorales (Mucoromycotina) is one of the factors to be opportunistic pathogens, causing mucormycosis. Among thermotolerant mucoralean fungi, Burkholderiaceae-related endobacteria (BRE) are rarely found and the known range of hosts is limited to Rhizopus spp. The phylogenetic divergence of BRE has recently expanded in other fungal groups such as Mortierellaceae spp. (Mortierellomycotina); however, it remains unexplored in Mucorales. Here, we found a thermotolerant mucoralean fungus obtained from a litter sample collected from Haha-jima Island in the Ogasawara (Bonin) Islands, Japan. The fungus was morphologically, phylogenetically, and physiologically characterized and proposed as a new species, Saksenaea boninensis sp. nov. Besides the fungal taxonomy, we also found the presence of BRE in isolates of this species by diagnostic PCR amplification of the 16S rRNA gene from mycelia, fluorescence microscopic observations, and isolation of the bacterium in pure culture. Phylogenetic analysis of the 16S rRNA gene of BRE revealed that it is distinct from all known BRE. The discovery of a culturable BRE lineage in the genus Saksenaea will add new insight into the evolutional origin of mucoralean fungus-BRE associations and emphasize the need to pay more attention to endofungal bacteria potentially associated with isolates of thermotolerant mucoralean fungi causing mucormycosis.

A new genus Unguispora in Kickxellales shows an intermediate lifestyle between saprobic and gut-inhabiting fungi.

Kickxellomycotina encompasses two fungal groups: a saprobic group in excrement and soil and an arthropod gut-inhabiting group. The evolutionary transition between these two lifestyles is unclear due to the lack of knowledge on intermediate forms and lifestyles. Here, we describe a new species, Unguispora rhaphidophoridarum, that was isolated from the excrement of cave crickets (Rhaphidophoridae) in Japan. This species has a novel lifestyle that is intermediate between the saprobic and gut-inhabiting groups. The new genus Unguispora is a member of the Kickxellales and characterized by the sterile appendages born on the sporocladium and by the claw-like ornamentation of the sporangiole. Phylogenetic analysis based on 18S and 28S nuclear ribosomal DNA showed that this fungus is distinct from all known kickxellalean genera and is sister to Linderina. The sporangiospore of the new species germinated only in anaerobiosis and grew in a yeast-like form. The yeast-like cells, defined as "secondary spores," germinated into hyphae in aerobiosis. In the alimentary tract of cave crickets, the sporangiola are attached to the proventriculus (foregut) by the claw-like ornamentation and multiplicate in the same yeast-like form as under culture. We introduce a new term, "amphibious fungi," to describe fungi that have two life stages, one outside and the other inside the host gut, like U. rhaphidophoridarum. The discovery of an amphibious fungus in Kickxellales, which was formerly considered to be only saprobic, suggests that Kickxellomycotina has evolved in association with the animal gut.

Revisiting the isolation source after the first discovery: Myconymphaea yatsukahoi on excrements of Lithobiomorpha (Chilopoda).

Myconymphaea yatsukahoi is a fungus that has only been isolated once from a forest in the Sugadaira Research Station, Nagano, Japan. Over 20 y have passed since its first discovery but since then it has not been rediscovered. Here, we re-isolated M. yatsukahoi from the type locality and another location, Tambara Moor, Gunma, Japan. Sporophores of this species were detected by direct field observation in Sugadaira and by induction from soil from Tambara. We attempted to narrow down isolation sources of this species by investigating the excrements of Lithobiomorpha and Scolopendromorpha centipedes, which are frequently found in the two locations where the species is distributed. In both locations, we found M. yatsukahoi in the excrements of Lithobiomorpha but not Scolopendromorpha. Myconymphaea yatsukahoi appears to be a coprophilous fungus and the excrements of the predators living in soil may be promising isolation sources for understanding the hidden diversity of kickxellalean fungi.

Revision of the genus Aciculosporium (Clavicipitaceae) with a description of a new species on wavyleaf basketgrass, and proline-containing cyclic dipeptide production by A. take.

The genus Aciculosporium (Clavicipitaceae, Hypocreales, Ascomycota)was established in 1908 for A. take , which is the causal fungus of witches' broom of bamboo. Although the original description was valid at that time, a type specimen for A. take has not been designated. To standardize the use of this genus and species name, a neotypification and reference specimen of A. take are proposed. Multilocus phylogenetic analyses based on DNA sequences from 28S rDNA, TEF, Tub2, Mcm7, and RPB2 revealed that A.sasicola is from a different lineage to A. take, and other specimens from wavyleaf basket grass (Oplismenus undulatifolius) represent a distinct species proposed here as Aciculosporium oplismeni sp. nov. Chemical analysis using mass spectrometry and nuclear magnetic resonance spectroscopy showed that A. take produces four proline-containing cyclic dipeptides, which are moieties of ergot alkaloids. However, ergot alkaloids, lolines, peramine, indole-diterpenes, and lolitrem were not detected in the culture solvent. This study offers clarification of the lineage and morphology of this genus.

Revisiting the isolation source after half a century: Emericellopsis mirabilis on a yellow-green alga.

Fungi-algae interactions, such as lichen-forming fungi and parasitic chytrids on phytoplankton, are common in ecosystems. In contrast, interactions between filamentous fungi and soil algae that can be observed with the naked eye have been given little attention and remain unexplored. Here, we report a fungus that was associated with a visible symptom of dead algae on a soil surface in Sugadaira-kogen, Nagano, central Japan. Acremonium-like conidiophores were growing on vesicles and dead bodies of a yellow-green alga, Botrydium granulatum. The fungus was identified as Emericellopsis mirabilis based on its morphology by microscopic observation, phylogenetic analysis, and the similarity of the isolation substrate with the first description of the species. Co-culture experiments showed a filamentous cell differentiation of the alga by the fungus, but no harmful or beneficial effects on algal growth. Therefore, we speculate that E. mirabilis is a facultative parasite of B. granulatum under natural conditions.

Revision of Xylonaceae (Xylonales, Xylonomycetes) to include Sarea and Tromera.

The resinicolous fungi Sarea difformis and S. resinae (Sareomycetes) were taxonomically revised on the basis of morphological observations and phylogenetic analyses of the nucleotide sequences of the nSSU-LSU-rpb1-rpb2-mtSSU genes. The results of phylogenetic analyses show that S. difformis and S. resinae are grouped with members of Xylonomycetes. According to the results of phylogenetic analyses and their sexual and asexual morphs resemblance, Sareomycetes is synonymized with Xylonomycetes. Although Tromera has been considered a synonym of Sarea based on the superficial resemblance of the sexual morph, we show that they are distinct genera and Tromera should be resurrected to accommodate T. resinae (= S. resinae). Xylonomycetes was morphologically re-circumscribed to comprise a single family (Xylonaceae) with four genera (Sarea, Trinosporium, Tromera, and Xylona) sharing an endophytic or plant saprobic stage in their lifecycle, ascostroma-type ascomata with paraphysoid, Lecanora-type bitunicate asci, and pycnidial asexual morphs. Phylogenetic analyses based on ITS sequences and environmental DNA (eDNA) implied a worldwide distribution of the species. Although Symbiotaphrinales has been treated as a member of Xylonomycetes in previous studies, it was shown to be phylogenetically, morphologically, and ecologically distinct. We, therefore, treated Symbiotaphrinales as Pezizomycotina incertae sedis.

Striatal necrosis caused by Lichtheimia ramosa in a neonatal calf.

A 12-day-old male calf that did not want breast milk from birth died following neurological signs such as staggering. Postmortem examination revealed bleeding and encephalomalacia in the left striatum and frontal lobe. Histopathologically, necrotic granulomatous encephalitis with numerous fungi was detected. The fungi were positively stained with anti-Rhizomucor mouse monoclonal antibodies. Lichtheimia ramosa was detected in formalin-fixed paraffin-embedded samples of the affected tissue by molecular methods. To the best of our knowledge, striatal necrosis caused by L. ramosa in a neonatal calf has not been reported. This study provides the first evidence of striatal necrosis caused by L. ramosa in a neonatal calf.

The Enigmatic Snow Microorganism, Chionaster nivalis, Is Closely Related to Bartheletia paradoxa (Agaricomycotina, Basidiomycota).

Chionaster nivalis is frequently detected in thawing snowpacks and glaciers. However, the taxonomic position of this species above the genus level remains unclear. We herein conducted molecular analyses of C. nivalis using the ribosomal RNA operon sequences obtained from more than 200 cells of this species isolated from a field-collected material. Our molecular phylogenetic analyses revealed that C. nivalis is a sister to Bartheletia paradoxa, which is an orphan basal lineage of Agaricomycotina. We also showed that C. nivalis sequences were contained in several previously examined meta-amplicon sequence datasets from snowpacks and glaciers in the Northern Hemisphere and Antarctica.

Taxonomic study of Endogonaceae in the Japanese islands: New species of Endogone, Jimgerdemannia, and Vinositunica, gen. nov.

Species of Endogonaceae (Endogonales, Mucoromycotina) are characterized by the formation of relatively large sporocarps and zygosporangia. Numerous species in this family remain undescribed or have unclear phylogenetic positions. In Asia specifically, the species diversity of this family is almost completely unknown. However, many mycobionts of bryophytes belonging to several novel clades in Endogonaceae have recently been identified phylogenetically. Therefore, establishing a robust taxonomic system for this family is essential. We obtained numerous sporocarps of undescribed Endogonaceae-like species from the Japanese islands. Morphological observation and multilocus phylogenetic analysis of nuc 18S rDNA (18S), nuc 28S rDNA (28S), and portions of two nuclear protein-coding regions-translation elongation factor 1-alpha (tef1) and RNA polymerase II large subunit (rpb1)-from these species resulted in the description of one new species each of Endogone and Jimgerdemannia and two new species of Vinositunica, gen. nov. Because Vinositunica is characterized by purplish sporocarps and red-wine-colored chlamydospores up to 700 µm in diameter, we emended the definition of Endogonaceae.

Aposymbiosis of a Burkholderiaceae-Related Endobacterium Impacts on Sexual Reproduction of Its Fungal Host.

Bacterial endosymbionts inhabit diverse fungal lineages. Although the number of studies on bacteria is increasing, the mechanisms by which bacteria affect their fungal hosts remain unclear. We herein examined the homothallic isolate, Mortierella sugadairana YTM39, harboring a Burkholderiaceae-related endobacterium, which did not produce sexual spores. We successfully eliminated the bacterium from fungal isolates using ciprofloxacin treatment and asexual spore isolation for germinated asexual spores. Sexual spore formation by the fungus was restored by eliminating the bacterium from isolates. These results indicate that sexual reproduction by the fungus was inhibited by the bacterium. This is the first study on the sexual spore infertility of fungal hosts by endofungal bacteria.