Conidium Ontogeny Research Articles

Xiuguozhangia macrospora (Pezizomycotina: Ascomycota)—a new species of bambusicolous fungi from India

Xiuguozhangia macrospora, a new conidial fungus, collected from India on dead bamboo stems is described. The species is characterized by smaller conidiophores than other reported species, holoblastic conidial ontogeny with monoblastic, terminal, lageniform proliferating conidiogenous cells, along with distinctly large, solitary, dictyoseptate, 1–3 appendaged, brown conidia composed of several compact rows of cells. Comparison with related species and a key to species of Xiuguozhangia is also presented.

First Report of a New Postharvest Disease of Pear Fruit Caused by Ceratocystis fimbriata in Kunming, China.

Pear (Pyrus pyrifolia (Burm.f.) Nakai) is widely planted in China and plays a key role in economy. In the autumn of 2016, five pear fruits showing symptoms of brown rot (Fig. 1A) were found in a Suancun farmer market in Kunming, Yunnan Province, China (25°02' N; 102°42' E). The incidence of this disease in postharvest pear fruits ranged from 2 % to 5 % in this city. Three fruit samples were taken to run further tests. The decayed area of the fruit was soft, brown, slightly sunken, and circular. Carrot baiting was used to isolate the pathogen from symptomatic tissue (Moller et al. 1968). Primary isolates were made by transferring ascospore drops from the tips of the perithecia formed on the carrot discs onto PDA plates. Single ascospore cultures were generated by transferring single ascospores to potatoe dextrose agar (PDA) plates. Cultures were incubated 7 days at 25°C with a 12-h light/12-h dark cycle. In culture, mycelium was initially white, turned to a shallow celadon and gradually to grey-greenish later. Measurements were made 10 days after the formation of perithecia. Six pure cultures (lik-1~lik-6) were stored at -80 °C in 15% glycerol and stored at the State Key Laboratory for Conservation and Utilization of Bio-Resources of Yunnan Agricultural University. Four isolates (lik-1~lik-4) produced ascomatal bases that were submerged in the agar. Bases (Fig. 1E) were globose, black, 192.15 to 250.81 µm wide, 192.94 to 251.31 µm long, and had straight necks terminating in ostiolar hyphae (Fig. 1F) that were divergent, hyaline, and 74.19 to 116.33 µm long. Asci were not observed. Ascospores (Fig. 1I) were ovoid, hat-shaped (dimensions 3.2 to 5.1 × 2.3 to 4.6 µm). Conidiogenous cells were with enteroblastic conidium ontogeny, flask-shaped or tubular, 65.3 to 130.6 μm long, and produced cylindrical, straight aseptate conidia (8.5 to 18 × 2.5 to 3.5 µm) (Fig.1 G). All isolates produced dark brown, 10.07 to 13.08 ×8.51 to 11.64 µm aleurioconidia (Fig. 1H). Two (lik-1, lik-3) of six isolates were used for molecular identification and genomic DNA was extracted using the CTAB method (Lee & Taylor 1990). The primers ITS1 and ITS4, EF1F and EF2R were used to amplify and sequence the rDNA-ITS and TEF-1α regions (Thorpe et al. 2005; Jacobs et al. 2004). The sequences of rDNA-ITS of the isolates lik-1 and lik-3 (GenBank Accession Nos: MF153994, MF153993) showed 99.49% similarity to AF395679 (C. fimbriata isolate CMW2219). Additionally, the TEF-1α sequences of isolates lik-1 and lik-3 (GenBank Accession Nos: KY708912, KY708915) showed 100% identify to MF347676 (C. fimbriata isolate CM18). Based on symptoms, morphological characteristics, rDNA-ITS and TEF1-α sequence analysis and pathogenicity, this fungus was identified as C. fimbriata. Pathogenicity tests were conducted using 2 isolates (lik-1, lik-3) and repeated three times. Three fresh pear fruits were disinfected with 75% alcohol, then they were wounded with a 2 mm hole punch and inoculated with 200 μL conidia suspension of the fungus (approximately 2.0 × 106 conidia / mL) on the fruit surface. After inoculation pear fruits were incubated in boxes at 25°C with a relative humidity of 80% and a 12-h light / 12-h dark cycle. Three pear fruits that served as controls were wounded by punching a 2 mm hole into the skin and inoculated with 200 μL sterile distilled water. Symptoms of rot were observed one week after inoculation (Fig.1 B). The diameter of the external lesion varied from 1.5 to 2.5 cm, on average 1.9 cm. When pears were cut, the white pulp had turned black and was rotting (Fig.1 C, D). The pathogen re-isolated from all inoculated symptomatic tissue was identical to the isolates originally obtained from the pear fruits at the market by morphology and ITS analysis. No symptoms developed on the control. The pathogenicity assay showed that C. fimbriata was pathogenic on pears. To our knowledge, this is the first report of C. fimbriata on pear in China. The spread of this disease may pose a threat to pear quality in China and further studies could be performed to determine effective disease management strategies.

Taxonomic revision of the acidophilic genus Acidiella (Dothideomycetes, Capnodiales) with a description of new species from Poland

Acidophilic fungi are characterized by their ability to tolerate very low pH conditions and to grow optimally below pH 5. The genus Acidiella (Dothideomycetes, Capnodiales, Teratosphaeriaceae) comprises acidophilic and acidotolerant fungi that are commonly distributed in highly acidic soils, drainages and waters worldwide. This study revises Acidiella taxonomy and provides alternative DNA barcodes. The morphological characteristics were revaluated by the investigation of conidial ontogeny, and knowledge of the ecology and biogeography of the genus is summarized. The new species Acidiella polonica isolated from highly acid (pH 2.7–3.8) technogenic soil developed on mine spoils in Poland is described here. This species is distinguishable by genetic markers, morphology and its ability to grow at pH 1. Based on DNA sequence and morphological comparisons, we also show that Acidiella uranophila (syn. Fodinomyces uranophilus) is a synonym of Acidiella bohemica. Among all species, A. bohemica is the most commonly isolated and is widely distributed over four continents. Interestingly, its distribution at the global scale is limited to extremely acidic substrates (pH < 4.0), often with high heavy metal toxicity, where it represents a dominant proportion of the mycobiota. Previous studies have also indicated its biotechnological potential in the bioaccumulation of rare earth elements and in mycoremediation. Other species are rare, and as in the case of A. americana and two undescribed species, they can also occur in non-acidic pH environments.

Taxonomy and phylogeny of the basidiomycetous hyphomycete genus Hormomyces.

The taxonomy of the genus Hormomyces, typified by Hormomyces aurantiacus, which based on circumstantial evidence was long assumed to be the hyphomycetous asexual morph of Tremella mesenterica (Tremellales, Tremellomycetes) or occasionally Dacrymyces (Dacrymycetales, Dacrymycetes), is revised. Phylogenies based on the three nuc rDNA markers [internal transcribed spacers (ITS), 28S large ribosomal subunit nrDNA (28S) and 18S small ribosomal subunit nrDNA (18S)], based on cultures from Canada and the United States, suggest that the genus is synonymous with Tulasnella (Cantharellales, Agaricomycetes) rather than Tremella or Dacrymyces. Morphological studies of 38 fungarium specimens of Hormomyces, including the type specimens of H. callorioides, H. fragiformis, H. paridiphilus and H. peniophorae and examination of the protologues of H. abieticola, H. aurantiacus and H. pezizoideus suggest that H. callorioides and H. fragiformis are conspecific with H. aurantiacus while the remaining species are unlikely to be related to Tulasnella. The conidial chains produced by H. aurantiacus are similar to monilioid cells of asexual morphs of Tulasnella species formerly referred to the genus Epulorhiza. The new combination Tulasnella aurantiaca is proposed and the species is redescribed, illustrated and compared with similar fungi. The ecological niche of T. aurantiaca and its possible relationship to orchid root endophytes is discussed. A key to asexual genera with similar conidium ontogeny to T. aurantiaca is provided. Citation: Mack J, Assabgui RA, Seifert KA (2021). Taxonomy and phylogeny of the basidiomycetous hyphomycete genus Hormomyces. Fungal Systematics and Evolution 7: 177-196. doi: 10.3114/fuse.2021.07.09.

Mirohelminthosporium gen. nov. for an atypical Helminthosporium species and H. matsushimae nom. nov.

Mirohelminthosporium is proposed as a new genus for Helminthosporium bigenum, characterized by polytretic and blastic conidial ontogeny on the apical conidiogenous cells. A replacement name, Helminthosporium matsushimae, is proposed for the illegitimate later homonym H. cylindrosporum Matsush.

Morganjonesia gen. nov. for two atypical Corynespora and Teratosperma species

Morganjonesia is proposed as a new genus for two species, Corynespora calophylli and Teratosperma litchii, which have monotretic conidial ontogeny on the terminal conidiogenous cells and solitary, euseptate, verruculose, brown conidia with a single, subulate or acute, hyaline conidial appendage at the apex (sometimes with another downwardly-direct conidial appendage). Illustrations of both species are provided.

A new species of Alpestrisphaeria (Dothideomycetes) with monodictys-like anamorph and revision of three Monodictys species

Endophytic fungal strains isolated from the coastal plant Vitex rotundifolia in Taiwan were accommodated in Alpestrisphaeria according to an analysis of internal transcribed spacer (ITS) and large subunit ribosomal RNA gene sequences. Based on this analysis and on a unique monodictys-like anamorph, the species, A. monodictyoides, is proposed as new. Type specimens of three species of Monodictys were investigated. A new name is proposed for the invalid M. indica S.M. Singh & Barde (non M. indica K. Chowdhery & Rehill); the invalid M. saudii is considered sclerotium-like structures of a sterile mycelium and excluded from any taxonomic naming; M. torulosa is synonymized with M. fluctuata. Early stages of conidium ontogeny are suggested as potential phylogenetically significant markers for a future revision of the polyphyletic genus Monodictys.

Spadicoides matsushimae sp. nov., and Anisospadicoides gen. nov. for two atypical Spadicoides species

Anisospadicoides is proposed as a new genus for two species of Spadicoides, S. macrocontinua and S. macroobovata, that have polytretic and blastic conidial ontogeny on the apical conidiogenous cells. A new species, Spadicoides matsushimae, distinguished by broadly fusiform to navicular, mostly 2-septate, brown to dark brown conidia, is also described and illustrated.

Sporidesmium binserum sp. nov. from Binser forest of Almora, Himalaya, India

A new and interesting species of Sporidesmium was discovered during a survey of plant debris inhibiting litter decomposing microfungi in Binser forest, Almora, Uttarakhand, India. This new species, Sporidesmium binserum sp. nov., a dematiaceous hyphomycete was found on decaying leaf litter of the host plant Quercus leucotrichophora (oak). The key features of special interest that distinguish it from other morphologically similar species of Sporidesmium are macronematous, mononematous, percurrent proliferations towards the end in the flexuous multiseptate conidiophores with obtuse tip having distinctively curved, fusiform to subfusiform, 3-septate conidia, consist of 3 cells, second cell dark brown with slightly or distinctly constricted at the septa, tip cell of conidia highly curved and/or twisted, mostly flat and conic-truncated ends at base due to schizolytic secession. The conidial maturation is presumably synchronous with conidial ontogeny. Based on these features, the specimen is proposed here as a new species. Apart from it, a note on the current status of Sporidesmium sensu lato in India is also provided.

Studies in genera similar to Torula: Bahusaganda, Bahusandhika, Pseudotorula, and Simmonsiella gen. nov.

A generic key is presented to delimit Torula from seven hyphomycete genera whose type species were at one time included in the genus or whose conidium ontogeny and conidium development appear similar or superficially similar to that of Torula herbarum, the type of the genus. In Bahusaganda, two new species are described (B. elliseverhartii and B. simmonsii spp. nov.) and three new combinations made (B. ambrosiae, B. elaeodes, and B. heteromorpha combs. nov.). In Bahusandhika, one new species (B. hughesii sp. nov.) is introduced, and two new combinations made (B. rhombica and B. terrestris combs. nov.), along with emendations in the circumscription of B. caligans and B. intercalaris. Latorua is considered synonymous with Bahusandhika. In Pseudotorula, one new combination is made (P. sundara comb. nov.), and one emendation proposed (P. helica). The transfer of Dwayabeeja sundara, the type species of the genus, to Pseudotorula will require a new generic name to be introduced for D. aethiopica and D. cubensis. The new generic name Simmonsiella is established for Torula ndjilensis. Bahusandhika compacta is shown to be synonymous with Torula verrucospora.

English

This study shows the conidiomatal development of Pestalotiopsis disseminata (Thuen.) Stey., using light and transmission electron microscope. Light microscopic study showed the presence of non-ostiolate pycnidial conidiomata in culture, whereas it is known to produce only acervular conidiomata on leaves. Interestingly, the fungus showed the ultrastructure of the conidial wall in the coloured cells as well as the basal and apical hyaline cells with the appendages. P. disseminata was studied for the first time on the development of the conidiomata and conidia by light and transmission electron microscopes. &nbsp; Key words: Coelomycetes, Conidiomata, conidium ontogeny, appendages.

Cirrosporium novae-zelandiae, an enigmatic coelomycete with meristem arthroconidia, with ancestors in the Eurotiomycetes

A culture of Cirrosporium novae-zelandiae, the type species of a distinctive, monotypic coelomycete genus, was isolated from a specimen collected near the holotype locality in New Zealand. Light microscopic and environmental scanning electron microscopic observations confirm the details of the unusual meristem arthric conidium ontogeny presented in the protolog. For phylogenetic analysis, a dataset of 122 species representing nine classes of euascomycetes was assembled including sequences from nuclear small and large subunits (nc18S, nc28S) and mitochondrial small subunit (mr16S) ribosomal RNA and the largest and second largest subunits of RNA polymerase II (RPB1, RPB2). A five-gene phylogeny suggests that the fungus is phylogenetically related to the Eurotiomycetes. It sits alone on a long branch as a sister to the Mycocaliciales of the Mycocaliciomycetidae. Cirrosporium exhibits several morphological characters similar to those of members of the Mycocaliciales; however, the paucity of known anamorphs in this order does not offer any further clarification on possible relationships. It is clear that the rare and broadly distributed meristem arthric ontogenetic pattern is polyphyletic, occurring in widely separate groups of anamorphs of both the Ascomycota and Basidiomycota.

First Report of Leaf Spot and Necrotic Roots on Switchgrass Caused by Curvularia lunata var. aeria in the United States.

Curvularia lunata infects many grass species; however, switchgrass (Panicum virgatum L.) has not been reported as a host (2). In June 2009, small brown leaf spots and necrotic roots were observed on stunted 2-year-old 'Alamo' switchgrass on the University of Tennessee, Knoxville campus. Symptomatic leaf and root tissues were surface-sterilized in 95% ethanol for 1 min, 20% bleach for 3 min, and 95% ethanol for 1 min, and then air dried and placed on water agar amended with 10 mg/liter rifampicin (Sigma-Aldrich, St. Louis, MO) and 7.5 μl/liter Danitol (Valent Chemical, Walnut Creek, CA). Cultures were incubated at 25°C for 3 days. Hyphal tips were transferred to potato dextrose agar (PDA) and incubated at 25°C. Dark brown-to-black fungal colonies with black stromata formed. Conidiophores were dark brown, unbranched, septate, polytretic, sympodial, and geniculate at the apical region with rachis conidial ontogeny. Conidia were dark brown and cymbiform with three to four septations, with one or two central cells larger than the terminal cells. Spore size ranged from 17.5 to 30.0 × 8.8 to 12.5 μm (mean 21.6 × 10.8 μm). Morphological traits matched the description of C. lunata var. aeria (1). To test pathogenicity, fungal sporulation was optimized on PDA with pieces of sterile, moistened index card placed on each plate; cultures were incubated at 25°C with a 12-h photoperiod (3). After 14 days, conidia were dislodged in sterile water and the spore concentration adjusted to 8 × 104 conidia/ml. Ten pots, with about 15 plants per pot, of 6-week-old 'Alamo' switchgrass grown from surface-sterilized seed were inoculated with the spore suspension applied to the plant crown and surrounding soil with an aerosol sprayer. Prior to inoculation, roots were wounded with a sterile scalpel. Noninoculated plants (two pots), with roots also wounded, served as controls. To maintain high humidity, each pot was covered with a plastic bag and maintained in a growth chamber at 30°C with a 16-h photoperiod. Bags were removed after 3 days; plants were maintained as described for 6 weeks. Brown leaf spots and brown-to-black necrotic roots that matched symptoms on the naturally infected plants were observed in all inoculated plants; there were no symptoms of Curvularia infection on the controls. The fungus was reisolated from inoculated plants as described above. Genomic DNA was extracted from the original isolate and the reisolate from the pathogenicity test. PCR amplification of the internal transcribed spacer (ITS) regions from ribosomal DNA was performed with primers ITS4 and ITS5. PCR products of 503 bp were sequenced. There was 100% nucleotide identity for sequences of the original isolate and the re-isolate. The sequence was submitted to GenBank (Accession No. HQ130484.1). BLAST analysis of the fungal sequence resulted in 100% nucleotide sequence identity to the ITS sequences of isolates of C. affinis, C. geniculata, and C. lunata. On the basis of the smaller spore size and abundant stromata on PDA, the isolate was identified as C. lunata var. aeria. As switchgrass is developed as a biofuels crop, identification of new pathogens may warrant development of disease management strategies.

Grapevine powdery mildew (Erysiphe necator): a fascinating system for the study of the biology, ecology and epidemiology of an obligate biotroph.

Few plant pathogens have had a more profound effect on the evolution of disease management than Erysiphe necator, which causes grapevine powdery mildew. When the pathogen first spread from North America to England in 1845, and onwards to France in 1847, 'germ theory' was neither understood among the general populace nor even generally accepted within the scientific community. Louis Pasteur had only recently reported the microbial nature of fermentation, and it would be another 30 years before Robert Koch would publish his proofs of the microbial nature of certain animal diseases. However, within 6 years after the arrival of the pathogen, nearly 6 million grape growers in France were routinely applying sulphur to suppress powdery mildew on nearly 2.5 million hectares of vineyards (Campbell, 2006). The pathogen has remained a focus for disease management efforts ever since. Because of the worldwide importance of the crop and its susceptibility to the disease, and because conventional management with modern, organic fungicides has been compromised on several occasions since 1980 by the evolution of fungicide resistance, there has also been a renewed effort worldwide to explore the pathogen's biology and ecology, its genetics and molecular interactions with host plants, and to refine current and suggest new management strategies. These latter aspects are the subject of our review. The most widely accepted classification follows. Family Erysiphaceae, Erysiphe necator Schw. [syn. Uncinula necator (Schw.) Burr., E. tuckeri Berk., U. americana Howe and U. spiralis Berk. & Curt; anamorph Oidium tuckeri Berk.]. Erysiphe necator var. ampelopsidis was found on Parthenocissus spp. in North America according to Braun (1987), although later studies revealed isolates whose host range spanned genera, making the application of this taxon somewhat imprecise (Gadoury and Pearson, 1991). The classification of the genera before 1980 was based on features of the mature ascocarp: (i) numbers of asci; and (ii) morphology of the appendages, in particular the appendage tips. The foregoing has been supplanted by phylogeny inferred from the internal transcribed spacer (ITS) of ribosomal DNA sequences (Saenz and Taylor, 1999), which correlates with conidial ontogeny and morphology (Braun et al., 2002). The pathogen is obligately parasitic on genera within the Vitaceae, including Vitis, Cissus, Parthenocissus and Ampelopsis (Pearson and Gadoury, 1992). The most economically important host is grapevine (Vitis), particularly the European grape, V. vinifera, which is highly susceptible to powdery mildew. Disease symptoms and signs: In the strictest sense, macroscopically visible mildew colonies are signs of the pathogen rather than symptoms resulting from its infection, but, for convenience, we describe the symptoms and signs together as the collective appearance of colonized host tissues. All green tissues of the host may be infected. Ascospore colonies are most commonly found on the lower surface of the first-formed leaves near the bark of the vine, and may be accompanied by a similarly shaped chlorotic spot on the upper surface. Young colonies appear whitish and those that have not yet sporulated show a metallic sheen. They are roughly circular, ranging in size from a few millimetres to a centimetre or more in diameter, and can occur singly or in groups that coalesce to cover much of the leaf. Senescent colonies are greyish, and may bear cleistothecia in various stages of development. Dead epidermal cells often subtend the colonized area, as natural mortality in the mildew colony, the use of fungicides, mycoparasites or resistance responses in the leaf result in the deaths of segments of the mildew colony and infected epidermal cells. Severely affected leaves usually senesce, develop necrotic blotches and fall prematurely. Infection of stems initially produces symptoms similar to those on leaves, but colonies on shoots are eventually killed as periderm forms, producing a dark, web-like scar on the cane (Gadoury et al., 2011). Inflorescences and berries are most susceptible when young, and can become completely coated with whitish mildew. The growth of the berry epidermal tissue stops when severely infected, which may result in splitting as young fruit expand. Berries in a transitional stage between susceptible and resistant (generally between 3 and 4 weeks after anthesis) develop diffuse, nonsporulating mildew colonies only visible under magnification. Diffuse colonies die as berries continue to mature, leaving behind a network of necrotic epidermal cells (Gadoury et al., 2007). Survival over winter as mycelium in buds results in a distinctive foliar symptom. Shoots arising from these buds may be heavily coated with fungal growth, stark white in colour and stand out like white flags in the vine, resulting in the term 'flag shoots'. More commonly, colonization of a flag shoot is less extensive, and infection of a single leaf, or of leaves on one side of the shoot only, is observed (Gadoury et al., 2011).

The Powdery Mildews: A Review of the World's Most Familiar (Yet Poorly Known) Plant Pathogens

The past decade has seen fundamental changes in our understanding of powdery mildews (Erysiphales). Research on molecular phylogeny demonstrated that Erysiphales are Leotiomycetes (inoperculate discomycetes) rather than Pyrenomycetes or Plectomycetes. Life cycles are surprisingly variable, including both sexual and asexual states, or only sexual states, or only asexual states. At least one species produces dematiaceous conidia. Analyses of rDNA sequences indicate that major lineages are more closely correlated with anamorphic features such as conidial ontogeny and morphology than with teleomorph features. Development of molecular clock models is enabling researchers to reconstruct patterns of coevolution and host-jumping, as well as ancient migration patterns. Geographic distributions of some species appear to be increasing rapidly but little is known about species diversity in many large areas, including North America. Powdery mildews may already be responding to climate change, suggesting they may be useful models for studying effects of climate change on plant diseases.

Basal Rot of Hylocereus undatus Caused by Fusarium oxysporum in Buenos Aires, Argentina.

Night-blooming cereus (Hylocereus undatus A. Berger) is generally used as rootstock of ornamental cactus because of its rapid growth and tolerance to humid substrates. Since 2002, in Gran Buenos Aires, a new disease has been observed in grafted crops in all production stages. Incidence was as much as 30% in many greenhouses. Symptoms consisted of soft rot that started near the soil line and developed upward until it affected all the rootstock. The scion was not rotten, but died as a consequence of rootstock infection. All the roots were symptomless. For pathogen isolation, symptomatic tissues were surface disinfected by a 1-min immersion in 0.2% NaOCl, placed on potato dextrose agar (PDA), and incubated at 22 ± 2°C. Only a Fusarium spp. was consistently isolated in pure culture. Twenty healthy potted night-blooming cereus plants, 10 of them previously injured with needles on the rootstock near the soil line, were gently removed from the substrate and inoculated by a 1-min immersion of their base in a suspension of 1.4 × 106 conidia per ml of sterile distilled water, prepared from 15-day-old cultures. Ten control plants, five of them previously injured, were immersed in sterile distilled water. Inoculated and noninoculated plants were replanted in the original substrate, placed in a climatic chamber at 22 ± 2°C, and monitored for disease expression. Basal rot was observed on all injured inoculated plants 12 days after inoculation. Symptoms on undamaged plants appeared 22 days after inoculation. After 72 days of incubation, all inoculated plants were totally rotten. Control plants remained symptomless. The same pathogen was reisolated to fulfill Koch's postulates. For species identification, single-spore cultures were grown on PDA and carnation leaf agar in a climatic chamber at 23 ± 2°C with a 12-h darkness/near ultraviolet light regimen. The micromorphology and culture features, mainly conidial ontogeny, were consistent with descriptions of Fusarium oxysporum Schlechtend.:Fr. (1). The pathogen was able to penetrate undamaged tissues. Needle injuries accelerated infection. To our knowledge, this is the first report of Fusarium oxysporum on H. undatus in Gran Buenos Aires, Argentina. A culture of the pathogen was deposited at the fungal collection of PRHIDEB-CONICET (University of Buenos Aires) as BAFCult 3158. Reference: (1) P. E. Nelson et al. Fusarium species. An Illustrated Manual for Identification. The Pennsylvania State University Press, University Park, PA, 1983.

Polyancora globosa gen. sp. nov., an aeroaquatic fungus from Malaysian peat swamp forests

During an investigation of submerged leaves and twigs sampled from tropical peat swamp forests located in Peninsular Malaysia, an anamorphic fungus not attributable to a described genus was detected and isolated in pure culture. Conidial ontogeny was thoroughly studied and illustrated using both light and SEM, which revealed a unique conidial morphology. Analysis of partial nuLSU rDNA and ITS data revealed a phylogenetic position within the Xylariales ( Ascomycota), but family affiliation remained unclear.

New species, notes and key to the aeroaquatic genera Beverwykella and Ramicephala gen. nov.

Two new aeroaquatic fungi, Ramicephala sphaerospora gen. sp. nov. and Beverwykella clathrata sp. nov., are described and illustrated from tropical and subtropical latitudes. B. clathrata, a species similar to B. cerebriformis, deviates from the latter in having a clathrate outermost cell layer instead of tightly appressed cells, a feature unique in Beverwykella. The second species, Ramicephala sphaerospora gen. sp. nov., has a unique combination of features concerning conidial ontogeny and morphology, and is therefore placed in a new genus. The genus most similar to Ramicephala is Beverwykella, from which it differs in having: (1) globose, non-flattened conidia; (2) a large central globose cell giving rise to centrifugally branching, tightly packed chains of cells; and (3) a compact peripheral cell layer, the cells of which are tightly interlocked in a zipper-like form. Similarities of R. sphaerospora to species of Pseudaegerita, Candelabrum and Cristulariella are discussed. Illustrations of and a key to all described species of Ramicephala and Beverwykella are provided.

Ultrastructural studies of the patterns of conidiogenesis in Dacrymyces stillatus nees: Fries (basidiomycete)

New patterns of conidial formation on basidiospores and vegetative hyphae are identified, illustrated and described. The mechanisms of conidial ontogeny so far unsatisfactorilly studied are elucidated and now better understood. Several types of conidiogenous cells are described and their ontogeny better illustrated and explained. Arthroconidia of the fungi are for the first time studied at ultrastructural level and their mode of formation and secession as well better understood. Likewise, chlamydospores of D. stillatus are for the first time investigated at ultrastructural level, what enables a better observation of their structure and morphology and as well a better understanding of their origin and various modes of formation.

Pseudosigmoidea: A new genus for a hyphomycete (ATCC 16660) formerly identified as Sigmoidea prolifera.

A new hyphomycetous genus, Pseudosigmoidea, is established with a single species, P. cranei, based on ATCC 16660 previously identified as Sigmoidea prolifera. The conidial ontogeny of Pseudosigmoidea is enteroblastic, and its conidiogenesis is phialidic. On the other hand, Sigmoidea is redescribed with holoblastic conidial ontogeny and with conidiogenous cells proliferating sympodially.