Astrothelium pseudoferrugineum is a species of corticolous (bark-dwelling), crustose lichen in the family Trypetheliaceae. Found in Indonesia, it was formally described as a new species in 2016 by Dutch lichenologist André Aptroot. The type specimen was collected in 1937 by Pieter Groenhart on Jombang (Java); there, it was found in a disturbed rainforest growing on smooth tree bark. The lichen has a smooth and somewhat shiny to glossy, bright orange thallus with a cortex but without a prothallus. The orange crust is about 0.1 mm thick and covers areas of up to in diameter. The use of thin-layer chromatography shows the lichen contains an orange anthraquinone, possibly parietin. The main characteristics of the lichen that distinguish it from others in Astrothelium are its to , whitish pseudostromata. It is named for its similarity to Astrothelium ferrugineum, from which it differs in its glossier thallus and larger ascospores (measuring 28–31 by 9–11 μm).
