RESUMEN
Species that cannot be easily distinguished based on morphology, but which form distinct phylogenetic lineages based on molecular markers, are often referred to as cryptic species. They have been proposed in a number of fungal genera, including the basidiomycete genus Fomes. The main aim of this work was to test new methods for species delimitation in cryptic lineages of polypores, and to define useful characters for species identification. A detailed examination of a number of different Fomes strains that had been collected and isolated from different habitats in Italy and Austria confirmed the presence of distinct lineages in the Fomes fomentarius clade. Our zero hypothesis was that the Mediterranean strains growing on Quercus represent a species which can be delimited based on morphological and physiological characters when they are evaluated in statistically relevant numbers. This hypothesis was tested based on phylogenetic analysis of the rDNA ITS region, morphological characters of basidiomes and pure cultures, growth rates and optimum growth temperature experiments, mycelial confrontation tests, enzyme activity tests and volatile organic compound (VOC) production. The Mediterranean lineage can unambiguously be delimited from F. fomentarius. A syntype of an obscure and previously synonymized name, Polyporus inzengae, represents the Mediterranean lineage that we recognize as Fomes inzengae, a distinct species. The rDNA ITS region is useful for delimitation of Fomes species. Moreover, also a variety of morphological characters including hymenophore pore size, basidiospore size, and diameter of skeletal hyphae are useful delimiting characters. The ecology is also very important, because the plant host appears to be a central factor driving speciation. Physiological characters turned also out to be species-specific, e.g. daily mycelial growth rates or the temperature range of pure cultures. The production of VOCs can be considered as a very promising tool for fast and reliable species delimitation in the future.
RESUMEN
Seven species of Cortinarius, subgenus Telamonia, section Colymbadini and /Flavobasilis, are reported from conifer forests in the mountains of western North America. They typically produce basidiomes in the spring and summer. Only one species, C. colymbadinus, is widespread, occurring in Europe and western North America, but to date not reported from California. Cortinarius bridgei, C. flavobasilis, C. rumoribrunsi, C. vernalishastensis, and C. vernalisierraensis are new species. The first two are found throughout the western mountains, whereas the latter three thus far are known only from California. Cortinarius ahsii, a common species in the Rocky Mountains and Pacific Northwest, also has not been recorded from California.
Asunto(s)
Cortinarius/clasificación , Cortinarius/aislamiento & purificación , Análisis por Conglomerados , Cortinarius/citología , Cortinarius/genética , ADN de Hongos/química , ADN de Hongos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Bosques , Microscopía , Noroeste de Estados Unidos , Filogenia , Análisis de Secuencia de ADN , Tracheophyta/microbiologíaRESUMEN
Different distance-based threshold selection approaches were used to assess and compare use of the internal transcribed spacer (ITS) region to distinguish among 901 Cortinarius species represented by >3000 collections. Sources of error associated with genetic markers and selection approaches were explored and evaluated using MOTUs from genus and lineage based-alignments. Our study indicates that 1%-2% more species can be distinguished by using the full-length ITS barcode as compared to either the ITS1 or ITS2 regions alone. Optimal threshold values for different picking approaches and genetic marker lengths inferred from a subset of species containing major lineages ranged from 97.0% to 99.5% sequence similarity using clustering optimization and UNITE SH, and from 1% to 2% sequence dissimilarity with CROP. Errors for the optimal cutoff ranged from 0% to 70%, and these can be reduced to a maximum of 22% when excluding species lacking a barcode gap. A threshold value of 99% is suitable for distinguishing species in the majority of lineages in the genus using the entire ITS region but only 90% of the species could be identified using just the ITS1 or ITS2 region. Prior identification of species, lacking barcode gaps and their subsequent separate analyses, maximized the accuracy of threshold approaches.