Tyromyces is a genus of poroid fungi in the family Polyporaceae. It was circumscribed by mycologist Petter Karsten in 1881. The type species is the widely distributed Tyromyces chioneus, commonly known as the white cheese polypore. The phylogenetic position of Tyromyces within the Polyporales is uncertain, but it appears that it does not belong to the "core polyporoid clade". Tyromyces is polyphyletic as it is currently circumscribed, and has been described as "a dumping place for monomitic white-rot species with thin-walled spores."
Tyromyces fungi have fruit bodies that are pileate (i.e., with a cap) to resupinate (crust-like). Fruit bodies are short-lived, and often mostly white, but turning a darker colour when dry. The colour of the pore surface is usually white to cream, sometime with greenish tinges. Like the cap surface, it darkens when dry.
Microscopic characteristics
The hyphal system is either monomytic (meaning the fungus contains only generative hyphae, which in this case have clamps) or dimitic, containing both generative and skeletal hyphae. The spores are smooth, thin-walled, and hyaline (translucent). They are allantoid (long with rounded ends) to ovoid (egg-shaped), and are non-reactive with Melzer's reagent. There are no cystidia in the hymenium, although there may be cystidioles (sterile cells of about the same diameter and shape as an immature basidium that protrude beyond the surface of the hymenium).
Tyromyces causes a white rot in deciduous or coniferous trees. The genus has a cosmopolitan distribution.
Species
As of September 2016, Index Fungorum accepts 119 species of Tyromyces.
Tyromyces albiformis Quanten (1997) – Papua New Guinea
