Two new species of the genus Corollospora, namely, C. anglusa sp. nov. with its anamorph Varicosporina anglusa sp. nov. and C. portsaidica sp. nov., which were isolated from the coast of the Mediterranean Sea in Egypt, are described in this article based on morphological and molecular evidence. The two new species have one-septate ascospores. Corollospora anglusa resembles C. gracilis by having narrow one-septate hyaline ascospores; however, they differ in ascomata and ascospore dimensions and in pure culture characteristics. Single-ascospore culture of C. anglusa produces the conidia of its anamorph, whereas an anamorph has not been reported for C. gracilis. Varicosporina anglusa differs from the other two known Varicosporina species by having conidial branches that are filamentous, rectangularly branched, hypha like, and disarticulated into two- or one-celled fragments. Corollospora portsaidica is morphologically similar to C. cinnamomea, but the two species differ in the dimensions, shape, and ornamentation of the ascospores. The new Corollospora species were confirmed to be divergent from other similar Corollospora species based on phylogenetic analyses of partial sequences of the LSU rDNA region.

On decayed wood near a stream, tiny cyphelloid, hair-bearing, Flagelloscypha-like basidiomata were found coexisting with conidia of an aero-aquatic fungus, Peyronelina glomerulata. An isolate originating from the basidioma produced conidia of P. glomerulata by soaking the culture in water. Three additional strains originating from conidia of P. glomerulata produced immature basidiomata with basidium-like structures on the agar medium after about 4 months incubation. Fine structure of the hyphal septa of P. glomerulata was found to be of the dolipore type. Phylogenetic analysis based on sequences from the D1/D2 regions of the LSU rDNA showed that the strains from conidia and from a basidioma clustered together in the Flagelloscypha clade and nested within the Nia clade of Hymenomycetes. The culture studies and molecular phylogenetic analysis suggested that P. glomerulata has a Flagelloscypha teleomorph, a cyphelloid basidiomycete. The molecular data also indicate that P. glomerulata is phylogenetically related to the marine basidiomycetes, Nia and Halocyphina. Thus, this study revealed that cyphelloid basidiomycetes have evolved into both marine as well as freshwater habitats by morphological adaptations of the teleomorphs in the former and of the anamorph in the latter case.

Ceratocystiopsis, Ceratocystis, Grosmannia, and Ophiostoma species were isolated from Ips subelongatus and beetle-infested Japanese larch logs collected at several areas in central and northern Honshu Island, Japan, to determine constant associates of I. subelongatus. Ceratocystiopsis minuta, two species of Ceratocystis, three species of Grosmannia, and four species of Ophiostoma were isolated. Of the fungi isolated in the present study, G. laricis, O. brunneociliatum, and O. piceae were constant associates of the beetles. Ceratocystis fujiensis, Ceratocystiopsis minuta, and Ophiostoma sp. F were occasionally isolated with high frequencies of occurrence but were not consistent associates. Ceratocystis fujiensis was most often isolated as the leading fungal invasion in the sapwood of Japanese larch logs invaded by I. subelongatus, confirming that the fungus acts as a primary invader of sapwood in beetle-attacked logs.

A new species, Strobilomyces verruculosus, is described and illustrated. It is morphologically distinct from other species of Strobilomyces by having a verruculose pileus with small subpyramidal scales, a long and thick stipe with small warty to appressed scales, subdecurrent tubes, and incompletely reticulate basidiospores. Molecular phylogenetic analyses using the mitochondrial cytochrome oxidase subunit 3 (cox3) gene support that it belongs to the genus Strobilomyces and is highly differentiated from the other members of this genus found in Japan.

Native to Japan, Fallopia japonica, most frequently referred to as Japanese knotweed, is a highly problematic invasive weed, particularly in the UK and North America. During surveys for natural enemies of this plant in Japan, two species of Mycosphaerella were collected. One of these was identified as M. polygoni-cuspidati, and is redescribed and neotypified. Causing a damaging leaf spot disease of F. japonica throughout its natural range in Japan, it is absent from the host's exotic range. The restriction of M. polygoni-cuspidati to F. japonica in its center of origin, together with its severe impact on host fitness, indicates that this is a coevolved natural enemy with high potential as a classical biological control agent for the long-term management of this ecologically and economically important weed. In the field, the fungus has a reduced life cycle, with only spermogonia and pseudothecia (ascomata) being formed. Ascospores are the primary source of infection, and studies show that the mycelium from in vitro cultures is also infective and hyphae penetrate mainly via the stomata. A further, undescribed species of Mycosphaerella co-occurs with M. polygoni-cuspidati, here proposed as the new species M. shimabarensis. Both species have been studied using cultural, morphological and molecular phylogenetic methods.

We describe and illustrate three Heterobasidion species distributed in East Asia, based on both dried specimens and cultures. Heterobasidion parviporum, formerly known as H. annosum from Asia, is characterized by effused-reflexed basidiocarps with cuticulate pilei, small round pores, thin context and short tubes in each layer. Examination of the type specimen of Trametes insularis revealed that this is distinct from the East Asian species widely known as “H. insulare”. No prior correct name for this taxon exists, and thus we propose the name H. orientale sp. nov. Heterobasidion orientale is characterized by sessile to effused-reflexed basidiocarps covered by a thin crust, reddish brown pileus with a marginal white zone and regular to labyrinthiform pores. Heterobasidion ecrustosum sp. nov. is characterized by convex basidiocarps frequently covered by a crust only at the base, large regular pores and long tubes. Morphological characters of these three species are compared with other Heterobasidion species. Cultural characters of these three species are also described. All isolates show oedocephaloid conidiophores bearing subglobose to ovoid conidia. Conidia of H. parviporum are smaller than those of the other two species. Descriptions and a key to the known species of Heterobasidion are provided.

This fourth paper in the series considers five species of Inocybe occurring in Hokkaido, Honshu, and Kyushu. (1) Inocybe furfurea (section Tardae) is recorded from Hokkaido as new to Japan. (2) Inocybe luteola sp. nov. (section Tardae) is described from eastern Honshu (Chiba). It has smooth basidiospores and thick-walled caulocystidia descending to the middle of the stipe. (3) Inocybe napiformis sp. nov. [section Inocybe (= Cortinatae)], known from Hokkaido, appears close to Inocybe napipes, but characters of the metuloids distinguish the two species. (4) Inocybe grammata (section Marginatae) is recorded from Hokkaido and Nagano as new to Japan. (5) Inocybe pyriformis sp. nov. (section Marginatae) is described from Kyushu (Miyazaki). It has nodulose basidiospores and caulocystidia wholly covering the stipe surface. However, I. pyriformis is not typical in the section, lacking a marginate bulbous base in its stipe.

We isolated ophiostomatoid fungi from bark beetles infesting Pinus densiflora and their galleries at 24 sites in Japan. Twenty-one ophiostomatoid fungi, including species of Ophiostoma, Grosmannia, Ceratocystiopsis, Leptographium, and Pesotum, were identified. Among these, 11 species were either newly recorded in Japan or were previously undescribed species. Some of these fungal species were isolated from several bark beetles, but other species were isolated from only a particular beetle species. Thus, it is suggested that some ophiostomatoid fungi have specific relationships with particular beetle species. In addition, fungus–beetle biplots from redundancy analysis (RDA) summarizing the effects of beetle ecological characteristics suggested that the association patterns between bark beetles and the associated fungi seemed to be related to the niches occupied by the beetles.

Nucleotide sequences of the rDNA intergenic spacer (IGS) region in Pythium ultimum were determined in 16 clones obtained from three isolates differing in production of sexual organs. Several sequences with different lengths were detected in each isolate, showing heterogeneity in the IGS region. In addition, several tandem repeat regions were detected in all the clones. The sequences, length, and number of each copy largely varied among repeat regions. Length heterogeneity arose from the complex combination of the number of copy within the repeat regions. Furthermore, the nucleotide sequence of each copy and the number of repetition varied not only between isolates but also between clones from an isolate. Based on the sequence similarity and the number of copies in repeat regions, specific patterns different between homothallic P. ultimum and the Pythium group HS (hyphal swellings) were recognized in a few regions. These results suggest that these two groups have slight genetic differences in the IGS region, although the differences in most of the repeat regions were not enough to identify each group.

Morphological types of arbuscular mycorrhizae (AM) in crops and associated weeds were examined in agro-ecosystems. In total, 48 plant species (8 crops and 40 weeds) belonging to 43 genera in 18 families were examined. The number of plant species with Arum-type AM was higher than those with Paris-type AM in the examined plants. AM association was absent in 6 weeds, and the average colonization rate was 62.64% in crops and 52.92% in weeds. AM morphology has been reported in 2 crops and 21 weeds for the first time. The influence of plant identity on AM morphology was also analyzed by arranging the examined plants in a current plant phylogenetic scheme. This analysis showed there was a lack of relationship between plant classification and AM morphological type. Actually, the colonization types were not distinguished at the plant family level, but were mostly distinguished at the species level.

Mating tests among strains of Lentinula edodes distributed in Asia-Australasia were conducted. As a result, 26 strains were classified into three groups: 2 strains from Mt. Wilhelm in Papua New Guinea (PN1 group) showed intersterility with 7 strains from Mt. Albert Edward and Mt. Kaisenik in Papua New Guinea (PN2 group) and semicompatibility (clamp formation restricted to contact zone between paired monokaryons) with 17 strains from Asia-Australasia (AA group), whereas the strains of the PN2 group showed compatibility with the AA group. These results suggest that the shiitake populations distributed in Asia-Australasia including Papua New Guinea are in the process of speciation.