The apothecial disc is initially flat, becoming slightly convex, with colours ranging from light beige to brown-grey or brown.

[1] The excipulum is of the piperis-type and mostly hyaline (translucent), though it can appear brownish or blackish at the upper periphery, and lacks hydrophobic granules.

The epihymenium of Malmidea leucopiperis is either indistinct or slightly granular, and the hymenium stands 60–70 μm high and is hyaline.

These spores are broadly ellipsoid to fusiform, non-septate, and have a uniformly thickened wall with a halo of approximately 1 μm.

[1] Chemically, this species is characterized by a major presence of norsolorinic acid and the absence of atranorin, as determined through thin-layer chromatography.