Hydnomerulius pinastri is a fungal species of the monotypic genus Hydnomerulius within the Paxillaceae family. H. pinastri is a saprophyte whose nutritional mode creates a brown rot through H2O2 decay of cellulose and hemi-cellulose.[2] This species has not been thoroughly studied outside of taxonomic attempts to place it within the fungal tree. As such, its ecological role beyond as a wood decaying agent is unclear at this time. H. pinastri may be referred to colloquially as "spiny dry rot" or "spiny dry rot fungus".