RESUMEN

The objective of this work was to study the basidiosporogenesis and the intraspecific variation in the number of basidiospores produced per basidium in Agaricus brasiliensis with transmission (TEM) and scanning electron microscopy (SEM). A. brasiliensis produces predominantly tetrasporic basidia, but this trait may vary depending on the strain. For certain strains, such as CS2 and CS7, the frequency of bisporic and trisporic basidia was similar to, or greater than, that of tetrasporic strains. These results suggest that some strains of A. brasiliensis may be amphithallic; however, this behavior is variable and strain dependent. The development of basidia and basidiospores occurs asynchronously during basidiocarp production. The basidiospore cell wall is composed of three distinct layers and presents variable thickness. The conspicuous presence of lipid bodies also was observed in the basidiospores, while nuclei, mitochondria, vacuoles and dolipore septa could be visualized only in the basidia. The basidiospores generally are produced free but also may be enveloped by an extracellular matrix with unknown chemical composition. The presence of connection hyphae linking the basidia was observed for the first time in A. brasiliensis. This characteristic, so far not reported for other fungi, may represent a specific strategy of A. brasiliensis for exchanging nuclei and other cell material between basidial cells during basidiosporogenesis.

Asunto(s)

Agaricus/ultraestructura , Cuerpos Fructíferos de los Hongos/ultraestructura , Esporas Fúngicas/ultraestructura , Agaricus/crecimiento & desarrollo , Matriz Extracelular/ultraestructura , Hifa/ultraestructura , Meiosis , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Especificidad de la Especie

RESUMEN

Five ectomycorrhizal species of Scleroderma were identified from herbarium and field-collected specimens from Argentina. A new hypogeous species, Scleroderma patagonicum, was recorded in association with native Nothofagus spp. in Patagonia. The epigeous species S. albidum, S. areolatum, S. bovista and S. citrinum were associated with various exotic tree species. A phylogenetic analysis based on the ITS region of Scleroderma species, including S. patagonicum, illustrates its distinct status within Scleroderma, including its placement among species with reticulate spores. Descriptions with SEM images of the spores and a key to the species are provided.

Asunto(s)

Basidiomycota/clasificación , Magnoliopsida/microbiología , Micorrizas/clasificación , Filogenia , Microbiología del Suelo , Argentina , Secuencia de Bases , Basidiomycota/genética , Basidiomycota/aislamiento & purificación , Basidiomycota/ultraestructura , ADN de Hongos/química , ADN de Hongos/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Cuerpos Fructíferos de los Hongos/ultraestructura , Hifa/ultraestructura , Datos de Secuencia Molecular , Micorrizas/genética , Micorrizas/aislamiento & purificación , Micorrizas/ultraestructura , ARN de Hongos/genética , ARN Ribosómico 5.8S/genética , Análisis de Secuencia de ADN , Suelo , Esporas Fúngicas/ultraestructura , Simbiosis , Árboles

RESUMEN

A new ascomycete species, Natipusilla bellaspora, collected from submerged woody debris in a freshwater stream at Los Amigos Biological Station, Madre De Dios in the Peruvian Amazon is described and illustrated. This fungus is characterized by small, globose to subglobose, hyaline ascomata; small, globose to subglobose, eight-spored fissitunicate asci; one-septate, multiguttulate ascospores with two different gelatinous sheaths, an outer amorphous sheath that enlarges in water and an inner sheath that has a distinctive persistent shape and is attached to the ascospore apex. Morphologically N. bellaspora differs from other Natipusilla species in having larger ascospores and two ascospore sheaths. A second Natipusilla species, N. limonensis, is reported for the first time from Peru. Based on the unique morphological characters of taxa in Natipusilla and results of previous molecular phylogenetic analyses with other members of the Dothideomycetes, we establish Natipusillaceae fam. nov. for this unique tropical freshwater clade.

Asunto(s)

Ascomicetos/clasificación , Ascomicetos/ultraestructura , Agua Dulce/microbiología , Cuerpos Fructíferos de los Hongos/ultraestructura , Esporas Fúngicas/ultraestructura , Ascomicetos/aislamiento & purificación , Perú , Clima Tropical , Madera/microbiología

RESUMEN

Three new species of Clavulina (Cantharellales, Basidiomycota) are described from rainforests dominated by ectomycorrhizal trees of the leguminous genus Dicymbe (Fabaceae subfam. Caesalpinioideae) from the central Guiana Shield. Species of Clavulina typically form branched, coralloid basidiomata with amphigenous hymenia. However, the three species described here form resupinate or effuso-coralloid basidiomata, macromorphological forms previously unknown in Clavulina. Macromorphological, micromorphological, habitat and DNA sequence data are provided for each new species. Micromorphological features and DNA sequence data from the second largest subunit of DNA-dependant RNA polymerase II (rpb2) and internal transcribed spacer (ITS) and large subunit (28S) of the ribosomal repeat justify placement of these new species in Clavulina. Comparisons with described Clavulina species and other resupinate taxa within the Cantharellales are provided.

Asunto(s)

Basidiomycota/clasificación , Fabaceae/microbiología , Cuerpos Fructíferos de los Hongos/ultraestructura , Micorrizas/clasificación , Filogenia , Basidiomycota/genética , Basidiomycota/ultraestructura , ADN de Hongos/química , ADN de Hongos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Proteínas Fúngicas/genética , Guyana , Micorrizas/genética , Micorrizas/ultraestructura , ARN Polimerasa II/genética , ARN Ribosómico 28S/genética , Clima Tropical