Acanthothecis submuriformis is a species of corticolous (bark-dwelling) lichen in the family Graphidaceae.

Found in Brazil, it was formally described as a new species in 2022 by André Aptroot, Robert Lücking, and Marcela Eugenia da Silva M.Cáceres.

The type specimen was collected from the Parque Natural Municipal (Porto Velho, Rondônia); here the lichen was found growing on tree bark in primary rainforest.

Its asci are 8-spored, and its ascospores are hyaline, measuring 29–31 by 6–8 μm.

[1] Acanthothecis submuriformis contains lichexanthone, a lichen product that causes the thallus and ascomata margins to fluoresce yellow when lit with a long-wavelength UV light.