The fungus was originally described as a species of Hydnum by Portuguese botanist Félix Avelar Brotero in 1804.
[2] Rudolph Arnold Maas Geesteranus transferred it to the newly created genus Mycorrhaphium in 1962.
[5] Mycorrhaphium pusillum has a small fruit body with a rounded to fan-shaped cap measuring 12–19 mm (0.5–0.7 in) in diameter.
The hyphal system of the context is monomitic (containing only loosely arranged generative hyphae), although in the spines it is dimitic.
In these latter collections, it was found fruiting on mossy ground in forest dominated by birch trees.