Hebeloma vesterholtii

A Hebeloma belonging to section Theobromina occurring on calcareous soils under broadleaved trees such as Quercus or Fagus, and more rarely with conifers.

A recently described species that was formerly confused with H. theobrominum. Macroscopically, vesterholtii exhibits brownish pilei with yellowish or beige tones, whereas theobrominum is typically more distinctly reddish or brick-red.

Microscopically, vesterholtii consistently displays a spore quotient Q < 1.8, whereas theobrominum has Q > 1.8.

The microscopic study is based on a collection gathered in October in a calcareous beech wood in Orduña (Bizkaia). Additional images represent a previous collection on limestone under Quercus spp. in Pancorbo (Burgos).