Suillellus mendax is a species of bolete fungus found in Europe.

It was originally published as a species of Boletus when it was newly described in 2013,[2] but then transferred to Suillellus the following year.

[3] This species is morphologically very similar to the widespread Suillellus luridus, but differs in its predominantly acidophilous ecology, a mostly dull-coloured, finely felty cap and more narrowly ellipsoid to subfusiform spores measuring (12.4–)13.3–14.7(–15.5) × (4.5–)4.9– 5.5(–5.7) μm.

[3] Suillellus mendax forms ectomycorrhizal associations with beech (Fagus), oak (Quercus) and sweet chestnut (Castanea).

So far, it has been molecularly verified from Italy,[2] France[4] and the island of Cyprus.