Abstract
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.
Highlights
Fomes fomentarius sensu lato (s. lat.) is thought to be a polypore taxon with a wide distribution in Europe, Asia, Africa, and North America
Phylogenetic analysis Phylogenetic analyses were performed with 60 rDNA Ribosomal DNA internal transcribed spacers (ITS) sequences obtained from our Fomes isolates and selected sequences currently available in public databases (GenBank)
The phylogenetic tree allows for the distinction of two well-supported major lineages within the F. fomentarius species complex in Europe, representing Fomes fomentarius and another species of Fomes
Summary
Fomes fomentarius sensu lato (s. lat.) is thought to be a polypore taxon with a wide distribution in Europe, Asia, Africa, and North America. Lat.) is thought to be a polypore taxon with a wide distribution in Europe, Asia, Africa, and North America. It is commonly known as the “tinder fungus”, “hoof fungus”, “tinder conk”, “tinder polypore”, or “Iceman’s fungus”. Besides the widespread and important use as tinder, F. fomentarius was a valued medicinal polypore in European traditional medicine. Recent phylogenetic analyses based on multiple genetic markers indicated that F. fomentarius possibly contained cryptic species (Pristas et al 2013). Our earlier study indicated that a European lineage could possibly represent a separate species that could be differentiated based on growth characteristics and substrate differences (Dresch et al 2015). Our results clarify which methods and characters are most useful for distinguishing otherwise “cryptic” species in polypores
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