Brown Ascospores Research Articles

First Report of Ophiosphaerella agrostis Infecting Creeping Bentgrass in Canada.

Dead spot, also known as bentgrass dead spot or bermudagrass dead spot, is a relatively new disease of golf course putting greens and is caused by the pathogen Ophiosphaerella agrostis (1). The disease first was reported on a creeping bentgrass (Agrostis stolonifera) putting green in Maryland (2) and since has been identified on putting greens of creeping bentgrass and hybrid bermudagrass (Cynodon dactylon × C. transvaalensis) in the eastern and southern United States (3,4). In June 2004, disease symptoms resembling dead spot were observed on a golf course in southern Ontario. Small (≤3 cm) spots first appeared approximately 14 months after establishment of the sand-based, 'L-93' creeping bentgrass putting greens. The disease became more severe during the summer months and patches increased in size to as much as 5 to 8 cm in diameter. Dead spot infection centers remained visible throughout the winter months and the disease again became active during the spring of 2005. Bentgrass tissues growing adjacent to the periphery of active infection centers were orange-red to reddish-brown. Although dark brown ectotrophic hyphae were observed on bentgrass stolons, none were found on the roots. Few new infection centers occurred in 2005 and pseudothecia embedded within necrotic tissue only were observed in small numbers. No mature ascospores were observed when samples were collected during September 2005. A single fungal morphotype consistently was isolated from leaves and stolons with a rose-quartz color when grown for several days on potato dextrose agar. To demonstrate pathogenicity, 'L-93' creeping bentgrass seedlings were grown for 28 days in 10-cm-diameter pots containing an autoclaved greens-mix with a mechanical analysis of 94% sand, 5% silt, and 1% clay. Inoculum was prepared by placing mycelia from a hyphal-tipped isolate on an autoclaved mix of seed of tall fescue (Festuca arundinacea) and wheat (Triticum aestivum) bran (50% [vol/vol]), and grown at 24°C for 14 days. The inoculum (5 g) was embedded a few milliliters into the sand in the center of each pot (n = 5), and uninfested inoculum served as the untreated control. Pots were placed in enclosed plastic containers and incubated at room temperature (13 to 26°C) under natural light (replication 1) or under 14 h of light per day from fluorescent lights (replication 2). After 7 days, tissue along the periphery of each inoculation point became covered in a pink mycelium, and newly infected leaves appeared tan or brownish-red. Most plants were dead after 22 to 28 days of incubation. Reisolation of the pathogen from necrotic leaves produced fungal colonies similar in color, morphology, and growth rate to the original isolates. Few pseudothecia developed on infected tissue but were present in large numbers on infested tall fescue seed. Bitunicate asci containing spirally twisted filiform ascospores were observed. Light brown ascospores (n = 50) were 7 to 15 septate and measured 1.9 to 3.6 μm × 60.7 to 147.9 μm. On the basis of field symptoms, morphological characteristics, and pathogenicity tests, the pathogen was identified as O. agrostis. To our knowledge, this is the first report of dead spot on creeping bentgrass in Canada and of O. agrostis outside the United States.

Dyrithiopsis lakefuxianensis gen. et sp. nov. from Fuxian Lake, Yunnan, China, and notes on the taxonomic confusion surrounding Dyrithium

A new taxon with Dyrithium-like characteristics was collected from Lake Fuxian in China. The taxon is typical of the Amphisphaeriaceae in that it has relatively large, ostiolate, immersed ascomata, unitunicate asci with a J+ subapical ring, and brown ascospores. It is similar to Dyrithium in that it has muriform ascospores, but considerable confusion surrounds this genus. In Dyrithium asci are bitunicate and lack a J+ subapical ring, while this was not true of our species. A new genus, Dyrithiopsis, therefore is established to accommodate this new taxon. Details of its anamorph also are provided, based on cultural studies. Parsimony analyses of part of the large-subunit rDNA provide further evidence to support the familial placement of this new genus in the Amphisphaeriaceae. The taxonomic position of Dyrithium also is discussed.

Dyrithiopsis lakefuxianensis gen. et sp. nov. from Fuxian Lake, Yunnan, China, and Notes on the Taxonomic Confusion Surrounding Dyrithium

A new taxon with Dyrithium-like characteristics was collected from Lake Fuxian in China. The taxon is typical of the Amphisphaeriaceae in that it has relatively large, ostiolate, immersed ascomata, unitunicate asci with a J+ subapical ring, and brown ascospores. It is similar to Dyrithium in that it has muriform ascospores, but considerable confusion surrounds this genus. In Dyrithium asci are bitunicate and lack a J+ subapical ring, while this was not true of our species. A new genus, Dyrithiopsis, therefore is established to accommodate this new taxon. Details of its anamorph also are provided, based on cultural studies. Parsimony analyses of part of the large-subunit rDNA provide further evidence to support the familial placement of this new genus in the Amphisphaeriaceae. The taxonomic position of Dyrithium also is discussed.

New species of Thielavia, with a molecular study of representative species of the genus

Two new thermotolerant species of Thielavia were isolated from Easter Island and India, after treating soil samples with 65% (v/v) ethyl alcohol: T. intermedia sp. nov. characterized by large, obovate, dark brown ascospores with a terminal germ pore; and T. arxii sp. nov. distinguished by the large, ellipsoidal to fusiform, brown ascospores with a prominent, lateral to medial germ pore. A phylogenetic study of the ITS-5.8S rDNA sequences of 18 species of Thielavia and Melanocarpus thermophilus was performed. This analysis revealed that T. intermedia could be the ancestor of the remaining species and that all the species tested were genetically closely related.

Sporostigma, a new calicioid genus in Arthoniales

Abstract:The new genus Sporostigma is introduced for the remarkable species Arthonia melaspora. The genus is characterized by mazaediate ascomata and dark brown ascospores. Relationships with other genera are discussed.

Ultrastructural studies of Trematosphaeria malaysiana sp. nov. and Leptosphaeria pelagica

Trematosphaeria malaysiana sp. nov. is described based on light microscope and ultrastructural studies. It was found on driftwood, exposed test blocks of Avicennia marina and Rhizophora apiculata, and split twigs of R. apiculata exposed in Kuala Selangor and Morib mangroves, Malaysia. T. malaysiana is characterized by striate, pale brown ascospores and trabeculate pseudoparaphyses. Ascospore cell walls are two layered, an outer thick layer comprising fibrillar mucilaginous material, and an inner bilamellate layer (the inner layer electron-transparent; the outer electron-dense and containing melanin). Both T. malaysiana and Leptosphaeria pelagica were examined at the transmission electron microscope level and their structure compared with that of other bitunicate ascomycetes. T. malaysiana and L. pelagica were similar in that the mucilaginous sheath was the outer most layer, in the former the spore wall was two layered while in L. pelagica it was three layered. In L. pelagica the spore wall was smooth, while in T. malaysiana it was longitudinally striate.

Lichenopyrenis galligena (Pleomassariaceae), a new genus of gall-forming lichenicolous fungi on Leptochidium

The new genus Lichenopyrenis is described for L. galligena, a cecidiogenous species parasitic on the lichen Leptochidium albociliatum. This genus is characterized by perithecioid ascomata with a cellular wall, formed by relatively large, somewhat compressed cells, fissitunicate, I- asci, wide hamathecium filaments, and 1-septate, pale orange brown ascospores with distoseptate thickenings which at maturity are seemingly bulging out of the exospore wall at the septum and apices. The conidia have a rhexolytic type of secession, and are attached to the conidiogenous cells by a separating cell. Lichenopyrenis is referred tentatively to the family Pleomassariaceae.

Studies on Amphisphaeriales: The Cainiaceae

The Cainiaceae is revived to accommodate Atrotorquata, Arecophila, Cainia, Ceriophora and Reticulosphaeria , all of which are described and illustrated. Ommatomyces is also included in the family and discussed. The essential characteristics of the family are ascomata which are usually immersed under a clypeus, unitunicate asci with a complex, J+, apical apparatus comprising a series of rings, and brown ascospores which may have longitudinal germ slits, striations, reticulate ornamentations and/or germ pores.

Ultrastructure of the dimorphic ascospores in Mamillisphaeria dimorphospora

The ultrastructure of the dimorphic ascospores of Mamillisphaeria dimorphospora are illustrated. The small brown ascospores differ from the larger hyaline ascospores in having a thick melanin layer in the ascospore wall. They are also 2–3 times smaller and do not germinate on PDA. The significance of these observations with respect to dispersal of aquatic fungi is discussed. The large hyaline ascospores may be morphologically adapted to dispersal in streams, while the smaller brown ascospores are thought to be adapted to aerial dispersal. The reasons for this are discussed. The method by which two spore types can be produced in separate asci in one ascoma is hypothesised.

Ascomauritiana lignicola gen. et sp. nov., an ascomycete from submerged wood in Mauritius

A new ascomycete Ascomauritiana lignicola gen. et sp. nov. is described and illustrated from a specimen collected on submerged wood in Mauritius. The taxon is compared with species of Arnium, Melanospora and Pustulipora, unitunicate ascomycetes having brown ascospores with germ pores and with species of Argynna, Caryospora, Lepidopterella and Zopfia. Ascomauritiana is characterized by large 5-septate, brown ascospores with polar germ pores and clavate, 4-spored asci that lack an apical ring and deliquesce early. Its taxonomic placement in the Ascomycetes incertae sedis is discussed.

The genus Roussoëlla, including two new species from palms in Cuyabeno, Ecuador

Four ascomycete species with brown 1-septate ascospores with wall ornamentation were identified from palms in Ecuador and Brunei. Asci were long cylindrical, relatively thick-walled, bitunicate with non-fissitunicate dehiscence, and the hamathecium was composed of trabeculae. These fungi are referred to Roussoella , and are described and illustrated in this paper, including two new species. A key to accepted species of Roussoella is provided.

Lithothelium japonicum (Lichenized Ascomycotina, Pyrenulaceae), a New Pyrenocarpous Lichen from Central Japan

Lithothelium japonicum Harada sp. nov. (lichenized Ascomycotina, Pyrenulaceae) is described from Chiba-ken, central Japan. It is characterized by a brownish green endophloeodic thallus, simple perithecia, non-gelatinized paraphyses with oil droplets, and 3-septate hyaline spores (10-14 X 4-5 ptm) with terminal lumina almost as large as the central ones. The genus Lithothelium is characterized by a crustose thallus having Trentepohlia as the phycobiont, perithecioid ascomata with lateral ostioles, almost simple paraphyses, asci with ocular chamber, and transversely-septate hyaline or brown ascospores with rounded lumina (Aptroot 1991a,b). The genus has about 20 species, mainly from the tropics, with records of three species in Asia: L. himalayense Upreti & Aptroot and L. obtectum (Muell. Arg.) Aptroot from India, and L. hyalosporum (Nyl.) Aptroot from the Maldives and New Guinea (Aptroot 1991b, Upreti & Aptroot 1996). There are no records of this genus from Japan; however, during my recent floristic survey in Chiba-ken, central Japan, a specimen was collected from the trunk of an old Castanopsis sieboldii in the precincts of a shrine that can be described as

Pterosporidium gen.nov. to accommodate two species of Anthostomella from mangrove leaves

Anthostomella rhizomorphae and Anthostomella rhizophorae, associated with foliar diseases of mangrove trees, are re-examined. In both species, the asci are thin-walled and clavate and contain unicellular brown ascospores. The ascospores lack a germ slit and are covered in a thin paperlike sheath. These species clearly do not belong in Anthostomella, and a new genus, Pterosporidium, is described to accommodate them. Pterosporidium is probably best accommodated in the Phyllachoraceae. Keywords: Anthostomella, fungi, Pterosporidium, mangrove, pathogen, Phyllachoraceae.

Prostratus, a new diaporthaceous ascomycete genus on Cyclobalanopsis from Taiwan

Prostratus cyclobalanopsidis gen. et sp. nov. is described and illustrated from Taiwan and placed in the family Melanconidaceae. This unusual ascomycete is characterized by horizontal stromatic ascomata, asci with distinct apical structures not turning blue in iodine and brown ascospores with a hyaline dwarf cell at the basal or apical end. Similar types of dwarf-celled ascospores are characteristic of some species of Anthostomella and Clypeosphaeria but this genus is clearly separable from them by its distinct diaporthaceous horizontal stromatic ascomata with an upwardly bending ostiolar beak and by asci with an apical structure not turning blue in iodine.

The Eremomycetaceae (Ascomycotina)

The Eremomycetaceae is shown to contain three species: Eremomyces bilateralis Malloch & Cain, Rhexothecium globosum Samson & Mouchacca, and Pithoascus langeronii von Arx, which is treated as a new combination in Eremomyces. The family is characterized by members having pseudoparenchymatous ascomatal initials, cleistothecia, clavate to ovoid evanescent asci, and one-celled hyaline to pale brown ascospores. Two of the three species have Arthrographis-like or Trichosporiella-like anamorphs. The pseudoparenchymatous ascomatal initials characteristic of this family strongly suggest that it should be included in the class Loculoascomycetes.

A New Species of Persiciospora from African Soil

Traditionally Melanospora Corda included those fungi with perithecial ascomata possessing long necks and a thin, pale-colored peridium, evanescent asci, and one-celled, brown ascospores with or without ornamentation. Similar fungi with non-ostiolate ascomata were placed in Microthecium Corda. In recent years there has been a tendency to evaluate the presence or absence of an ostiole as being of minor significance (Von Arx, 1973; Cailleux, 1971; Krug et al., 1983). This has resulted in Microthecium being synonymized with Melanospora (Von Arx, 1973; Cannon and Hawksworth, 1982). Melanospora was treated by Doguet (1955) while Microthecium has been considered by Udagawa and Cain (1969) and Hawksworth and Udagawa (1977). Further species have been added to both taxa (e.g. Morinaga et al.,1978; Udagawa and Takada, 1974). Von Arx (1981) pointed out that Sphaerodes Clem. is available for those species with ornamented spores which appear to represent a phylogenetic unit. Meanwhile Krug and Jeng (1979) erected Pteridiosperma for some discordant species while Rhytidospora was described by Jeng and Cain (1977) for another abnormal element in this complex. Cannon and Hawksworth (1982), while treating the British taxa, reappraised the relationship of Melanospora with related genera. This resulted in the erection of several new genera, of which one was Persiciospora Cannon & Hawksw. While studying fungi isolated from tropical

A new species of Anixiopsis

Anixiopsis biplanata sp.nov. is described as a new ascomycete isolated from soil at an altitude of 3100 m in Nepal. It is heterothallic and characterized by small, reddish brown ascospores (4 × 3 μm), which under the light microscope seem subrectangular to hexagonal in side view and appear smooth walled. Under the scanning electron microscope, however, they are tire shaped, ornamented with an equatorial reticulum and with two smooth, flat, lateral discs. Its anamorph is a Chrysosporium. Anixiopsis biplanata is briefly compared with the three other species already included in the genus Anixiopsis Hansen.

A revision of Achaetomium, Achaetomiella and Subramaniula, and some similar species of Chaetomium

The species included in Achaetomium, Achaetomiella and Subramaniula are studied, particularly with regard to their relationships with Chaetomium. Where available, living cultures have been examined, but inevitably much of the study has had to be based on dried material; this means that a number of the conclusions as to taxonomic relationships which are advanced are only tentative. Various specialized techniques have been employed during the research, including SEM examination, and measurement of growth rates under carefully controlled conditions. Achaetomium is restricted to three species, all having dark brown ascospores and apparently lacking periphyses; Achaetomiella is subsumed into Chaetomium in agreement with earlier authors; and the genus Subramaniula is expanded to include the new species S. irregularis P. Cannon & D. Hawksw. Three new combinations are proposed, Chaetomium luteum (Rai & Tewari) P. Cannon, C. strumarium (Rai et al.) P. Cannon and C. virescens var. thielavioideum (Chen) P. Cannon. Comparisons are made with taxa from related genera, and particularly with the species of Chaetomium which have reduced or inconspicuous ascomatal hairs. A key to those species in addition to the accepted ones of Achaetomium and Subramaniula, along with a number of other taxa with which they might be confused, is included.

A New Graminicolous Species of Xylaria

A new species in the Hypoxylaceae found growing on culms of Spartina patens is described as Xylaria psamathos. Immature ascospores lack appendages and are binucleate. Mature ascospores are uninucleate due to degeneration of one nucleus. The anamorph is sympodioconidial in a compact palisade. At the sandy margin of a North Carolina salt marsh, a fungus was discovered whose black, stipitate stromata grew from the buried, dead culms of Spartina patens (Ait.) Muhl. (FIG. 9c). The stromata were teleomorphs possessing characters of the Hypoxylaceae. The one-celled, brown ascospores had germ slits and the ascospores were contained within asci whose apical rings blued in Meltzer's reagent (FIGS. 5, 6, 9a). Appendages were lacking on immature ascospores examined by fluorescence microscopy, using the technique of Rogers (1975) (FIG. 4). The mitotic sequence within the ascospores was observed by staining with haematoxylin (technique by Rogers and Malmgren, 1977). Newly delimited ascospores are uninucleate. Following mitosis, immature ascospores are binucleate (FIG. 8). As maturation progresses, indicated by the darkening of the ascospores, one nucleus degenerates (FIG. 7). This mitotic sequence is, apparently, widespread among the hypoxylaceous fungi (Rogers and Malmgren, 1977; Rogers and Stiers, 1974 and references cited therein). The black surface of some of the stromata in the North Carolina collection cracked open and exposed inner tissues. The entostroma of one stroma differentiated to produce an anamorph (FIG. 9d) with conidia produced holoblastically in sympodial fashion. The conidiophores formed a compact palisade on the surface of the stroma. This anamorph type is associated with the genus Xylaria.

ADDITIONAL SPECIES OF PODODIMERIA (LOCULOASCOMYCETES)

Pododimeria, containing the brown‐spored species P. gallica and P. andina, is expanded to include species with hyaline as well as brown ascospores. Two new hyalodidymous taxa, P. juniperi and P. gelatinosa, are added to the genus. Species of Pododimeria occur as ectocommensals on living shoots of Cupressaceae or Podocarpaceae. Although the superficial mycelium may extend into the labyrinthine chambers enclosed by the imbricated scale leaves of the host, it does not penetrate the cuticle. The tiny, black, subglobose, uniloculate ascocarps taper basally to stromatic stipes. The bitunicate asci are interspersed with pseudoparaphyses composed of broad, irregularly shaped cells that readily break apart. The thick, brown to bluish‐green ascocarp wall of P. juniperi has a broad equatorial band of prosenchymatous cells. The ascocarp wall of P. gelatinosa is composed uniformly of subhyaline, gelatinous pseudoparenchymatous cells covered by a dark, amorphous crust.