Mazaediothecium mohamedii is a species of corticolous (bark-dwelling) and crustose lichen in the family Pyrenulaceae.

The type specimen was collected by the first author from the Field Studies Centre of the University of Malaya (Gombak, Selangor) at an elevation of 300 m (980 ft); here, in a tropical rainforest, the lichen was growing on the trunk of a hardwood on the side of the road.

The species epithet mohamedii refers to Professor Haji Mohamed, who arranged the field survey where this specimen was collected.

[1] Mazaediothecium mohamedii has a dull, cracked, pale creamy yellow thallus that lacks a cortex.

Mazaediothecium mohamedii contains lichexanthone, a lichen product that causes the thallus to fluoresce golden yellow when lit with a long-wavelength UV light.