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); there the lichen was found growing on tree bark in primary rainforest.
It has a smooth, ochraceous white thallus lacking a cortex and lacking a prothallus. Its asci are 8-spored, and its ascospores are hyaline, measuring 29âÂÂ31 by 6âÂÂ8 üm. The specific epithet refers to the (somewhat chambered) spores; all spores have between seven and nine transverse septa, but of the eifht spores in the ascus, only about two have a longitudinal septum.
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. This species and Acanthothecis tetraphora are the only species in genus Acanthothecis known to produce lichexanthone.