This research provides a comprehensive guide to identifying mushrooms in the genus Xerocomellus found in western North America. The study combines traditional morphological analysis with modern DNA techniques to clarify which species exist in this region and how to tell them apart. Impacts on everyday life: – Helps mushroom enthusiasts and experts accurately identify these fungi in nature – Improves our understanding of forest ecosystems and fungal biodiversity – Contributes to forest management and conservation efforts – Enables better monitoring of rare or endangered fungal species – Assists in understanding mycorrhizal relationships between fungi and trees