48 research outputs found
The anamorph genus <i>Knufia</i> and its phylogenetically allied species in <i>Coniosporium</i>, <i>Sarcinomyces</i>, and <i>Phaeococcomyces</i>
No full text Knufia endospora , a species described previously on the basis of cultured material, was found forming distinctive sporodochia on the bark of balsam poplar. Phylogenetic analyses of this fungus and some allied species indicated that (i) it forms a monophyletic group with Knufia cryptophialidica (type species of Knufia ) and with Coniosporium perforans , Coniosporium epidermidis and Phaeococcomyces chersonesos and (ii) P. chersonesos and Sarcinomyces petricola are conspecific. These Coniosporium and Phaeococcomyces species also shared major morphological characteristics with Knufia in culture and were morphologically and phylogenetically distant from the type species of their respective genera. The following new combinations are proposed: Knufia perforans (Sterflinger) Tsuneda, Hambleton & Currah; Knufia epidermidis (D.M. Li, de Hoog, Saunte & X.R. Chen) Tsuneda, Hambleton & Currah; and Knufia chersonesos (Bogom. & Minter) Tsuneda, Hambleton & Currah. Phaeococcomyces catenatus and Phaeococcomyces nigricans (type species of Phaeococcomyces) were morphologically similar but phylogenetically distant from each other and from Knufia. </jats:p
The Helvellaceae: Systematic revision and occurrence in northern and northwestern North America
No full text(0) Save to: more options The Helvellaceae: Systematic revision and occurrence in northern and northwestern North America Author(s): Abbott, SP (Abbott, SP); Currah, RS (Currah, RS) Source: MYCOTAXON Volume: 62 Pages: 1-125 Published: APR-MAY 1997 Times Cited: 9 (from Web of Science) Cited References: 236 [ view related records ] Citation Map Abstract: Epigeous genera of the Helvellaceae (Pezizales, Ascomycota) are separated into tribes Helvelleae and Gyromitreae on the basis of excipulum structure, while hypogeous genera are included as incertae sedis at the tribe level. Ornamentation of ascospores (SEM) is valuable in the delimitation of genera, subgenera, and species. New subgenera proposed are Gyromitra subgenus Melaleucoides subgen. nov., with warted, nonapiculate, biguttulate ascospores; Gyromitra subgenus Caroliniana subgen. nov., with coarsely reticulate ascospores with multiple spicules at the poles; Helvella subgenus Cupuliformae subgen. nov., with regularly cupulate apothecia, solid terete stipes, and broadly ellipsoidal, finely rugose ascospores; and Hydnotrya subgenus Cerebriformae subgen. nov., with globose, echinate ascospores. Gyromitra subgenus Discina is emended New combinations include Helvella subgenus Leucomelaenae comb. nov, Helvella subgenus Silvicolae comb. nov., Helvella subgenus Macropodes comb. nov., and Helvella subgenus Elasticae comb. nov. Epigeous taxa and hypogeous taxa with chambered ascocarps were studied in detail. Collections of 44 species in six genera (Gyromitra, Rhizina, Pseudorhizina, Helvella, Underwoodia, and Hydnotrya) from northern and northwestern North America are described. One extralimital genus (Gymnohydnotrya) and 15 species outside the study area are included with systematic notes. The known geographic range for many species is extended and there are several new records for North America (Helvella rivularis, H. verruculosa, H. unicolor). Maps and keys for taxa in northern and northwestern North America are provided
Ascomatal Morphogenesis in Myxotrichum arcticum Supports the Derivation of the Myxotrichaceae from a Discomycetous Ancestor
No full textElectron microscopy shows that ascomata of Myxotricum arcticum bear a striking resemblance to discocarps in morphogenesis and in previously overlooked aspects of gross morphology. Although mature ascomata of M. arcticum superficially resemble reticuloperidial cleistothecia common in the Onygenales, the bramble-like aggregation of thickwalled hyphae, previously considered to represent a closed peridium, forms a basket-like apothecium that overarches a distinct hymenium of stipitate, protunicate asci interspersed with paraphyses. There is no evidence of asci developing in chains and at different levels as is characteristic of the centrum of many Eurotiomycetes. Instead, more or less globose, stipitate and evanescent asci arise individually from penultimate cells of croziers and develop almost synchronously across a distinct hymenial layer derived from a richly branched network of crozier-bearing hyphae. After dissolution of the ascus wall, ascospores adhere to a membranous sheath that underlies the hymenium. These observations provide strong support for prior suggestions based on molecular phylogenetic comparisons that the Myxotrichaceae recently are derived from a helotialean ancestor. Observations of conidiogenesis show that the typical Oidiodendron anamorph is accompanied by a second conidiogenous form with ampullae and botryose clusters of blastic conidia
Patterns in the occurrence of saprophytic fungi carried by arthropods caught in traps baited with rotted wood and dung
No full textFungi from approximately 1700 individual arthropods that had been captured in traps set in aspen-dominated woodland in western Canada and baited with coyote dung, moose dung, white-rotted wood, brown-rotted wood and fiberglass were isolated in pure culture and identified. These data were analysed with principal components analysis (PCA) to determine whether different types of substrate attracted specific arthropods and whether these animals carried unique assemblages of fungi with known proclivities for the new habitat. Mycobiotic agar was used to restrict the numbers of fungi isolated and resulted in the recovery of 1687 isolates representing 65 species across 12 orders. Isolates of cosmopolitan fungal taxa such as species of Cladosporium, Penicillium, and Beauveria were the most numerous. Taxa with predilections for specific substrates, such as Myxotrichum and Cryptendoxyla that are known inhabitants of cellulose-rich materials (i.e. rotted wood), and various representatives of the keratinophilic Onygenales were recovered from arthropods attracted respectively to baits rich in cellulose and keratin. When traps were analysed according to the identity and numbers of arthropods captured, there was considerable overlap among clusters representing specific bait types, with traps baited with coyote dung being the most divergent partly because they captured significantly more arthropods than those baited with moose dung or rotted wood. When bait type was examined according to the identity and numbers of fungi on trapped arthropods the degree of overlap was also high although a few trends could be discerned. In particular traps baited with brown-rotted wood and coyote dung diverged slightly indicating that arthropods visiting these bait types were carrying somewhat different suites of fungi
Atradidymella muscivora gen. et sp. nov. (Pleosporales) and its anamorph Phoma muscivora sp. nov.: A new pleomorphic pathogen of boreal bryophytes
No full textDuring a survey of bryophilous fungi from boreal and montane habitats, 12 isolates of a hitherto unknown plant pathogenic member of the Pleosporales were recovered from Aulacomnium palustre , Hylocomium splendens , and Polytrichum juniperinum , and described as Atradidymella muscivora gen. et sp. nov. Atradidymella is characterized by minute, unilocular, setose pseudothecia having 2 – 3 wall layers; brown, fusiform, 1-septate ascospores; and a Phoma anamorph. The genus is distinguished from all other pleosporalean genera with brown, fusiform ascospores on the basis of ascospore and pseudothecium morphology and a highly reduced stroma that is localized within a single host cell. Atradidymella muscivora is distinguished by its minute pseudothecia ( < 115 μ m) and ascospores that are slightly allantoid and constricted at the septum with the upper cell often wider than the lower. Its anamorph, Phoma muscivora sp. nov., is morphologically distinguishable from P. herbarum in having smaller conidia. Parsimony analysis of the ITS rDNA region indicates A. muscivora has affi nities to the Phoma-Ascochyta-Didymella clade that is sister to the Phaeosphaeriaceae within the Pleosporales
Morphology and development of the reticuloperidial ascomata of Auxarthron conjugatum
No full textLight and electron microscopy showed that the reticuloperidium of thick-walled hyphae, characteristic of the mature ascoma of Auxarthron conjugatum, originated from branches that grew from the broad, gyre-like hyphal loops making up the ascomatal initials. Within the developing peridium, short, acropetally proliferating chains of prototunicate asci each arose from a single crozier and matured from base to tip. The walls of young asci were two-layered but evanesced as they matured with the outer layer dissolving before the inner one. Distal asci in some chains retained the inner wall, detached from adjacent asci by septum schizolysis and when transferred to fresh media produced germ tubes and mycelium. Ultraviolet epifluorescent staining with a DNA intercalator (Hoechst) indicated that these spore-like asci probably contained diploid nuclei. In normal asci, ascospores had an inner, electron lucent primary wall and a three-layered secondary wall. The deposition pattern of the middle layer of the secondary wall created the distinctive array of pits and ridges characteristic of the ascospores in this taxon. The production of ascospores, spore-like asci and arthroconidia, along with the tendency of ascospores to adhere in a mass, is interpreted as contributing to the reproductive flexibility and inoculum potential of A. conjugatum. In all respects the ascomata of A. conjugatum differed substantially from the morphologically similar taxon, Myxotrichum arcticum. These findings underscore the benefit of using DNA-based phylogenies in concert with cytological and ultrastructural observations for exploring selective pressures behind homoplasious characters and revealing novel structural features
Endoconidiogenesis in Endoconidioma populi and Phaeotheca fissurella
No full textDetails of the development of endoconidia were basically the same in Endoconidioma populi and Phaeotheca fissurella. In both species, endoconidiogenesis involved (i) subdivision of conidiogenous mother cells by septation to form two to several daughter cells; (ii) accumulation of an electrondense material between the daughter and mother cell walls; and (iii) separation of the daughter cells by septum schizolysis, accompanied by the dissolution of mother cell wall. Conidiomata of E. populi were unique in having a closed peridium and a locule filled with conidiogenous mother cells and, therefore, we proposed the new term, cleistopycnidium (pl. -a), for this structure. In the cleistopycnidium of E. populi, endoconidiation usually began in the core of the locule and spread outward. Release of endoconidia was by the degeneration of peridial cell walls
Evidence that the gemmae of Papulaspora sepedonioides are neotenous perithecia in the Melanosporales
No full textPapulaspora sepedonioides produces large multicellular gemmae with several, thick-walled central cells enclosed within a sheath of smaller thinwalled cells. Phylogenetic analysis of the large subunit rDNA indicates P. sepedonioides has affinities to the Melanosporales (Hypocreomycetidae). The development of gemmae in P. sepedonioides was characterized by light and scanning and transmission electron microscopy and was similar to previous ontogenetic studies of ascoma development in the Melanosporales. However instead of giving rise to ascogenous tissues the central cells of the incipient gemma became darkly pigmented, thick walled and filled with lipid globules while the contents of the sheath cells autolysed, leaving them empty and deflated at maturity. Both central cells and pre-autolytic sheath cells produced both germ tubes and new gemmae primordia, suggesting microcyclic conidiogenesis occurs in this species. Mature gemmae were nondeciduous or seceded by schizolytic secession and appear to have both perennating and disseminative potential. The evolution of these neotenous perithecial propagules may be driven by life-history and ecological factors selecting for functional versatility
Morphology and Phylogenetic Placement of Endoconidioma, a New Endoconidial Genus from Trembling Aspen
No full textEndoconidioma populi gen. et sp. nov. is described from black subicula on twigs of trembling aspen, Populus tremuloides, in Alberta, Canada. Pycnidium- like conidiomata are produced on twigs and in culture, but, unlike pycnidia, conidiomata of E. populi have a closed peridium and a locule filled with conidiogenous cells that form conidia endogenously. These endoconidia are hyaline, unicellular and released by the dissolution of the peridial cell wall. In addition to endoconidia, mostly two-celled conidia that form blastically from undifferentiated hyphae occur often in culture but are observed only occasionally on Populus twigs. No coelomycetous taxa have been reported to produce endoconidia, and both the morphological features and DNA sequence data demonstrate that Endoconidioma is distinct from the previously established endoconidial genera. Parsimony analyses of portions of the nuclear ribosomal RNA gene (SSU and ITS) suggest that Endoconidioma is closely related phylogenetically to members of the Dothideales and allied anamorphs in Hormonema and Kabatina
Pathogenesis of bryophyte hosts by the ascomycete Atradidymella muscivora
No full textAtradidymella muscivora (Pleosporales) is a bryophyte pathogen that infects the mosses Aulacomnium palustre , Hylocomium splendens , and Polytrichum juniperinum . Light and scanning electron microscopy and extracellular enzyme production were used to characterize the interactions between this fungus and its native hosts and the model host Funaria hygrometrica. Penetration was direct via hyphae or appressoria, and hosts responded by forming layered, darkly pigmented deposits at penetration sites, similar to the papillae formed by vascular plants in response to fungal infection. Infected hosts gradually became chlorotic as hyphae grew intracellularly, presumably killing host cells. Pycnidia of the Phoma anamorph ( P. muscivora ) and uniloculate pseudothecia were initiated as tightly packed masses of stromatic dematiaceous hyphae within a single host cell. Mature pycnidia and pseudothecia were erumpent. A new microniche among bryophilous fungi is described, whereby A. muscivora supplants the gemmae of Aul. palustre and exploits the normal nutrient-fl ow of the moss gametophyte. Atradidymella muscivora produced both cellulases and soluble polyphenolic oxidases, allowing it to also function as a saprobe and degrade the cell walls of bryophytes. The saprophytic and pathogenic abilities of A. muscivora suggest it may play a role in nutrient cycling, population dynamics, and small-scale disturbances in boreal ecosystems
