Cryptothecia methylmicrophyllinica is a species of corticolous (bark-dwelling) lichen in the family Arthoniaceae.

Found in Java, it was formally described as a new species in 2007 by André Aptroot and Jos Leo Spier.

The type specimen was collected by Pieter Groenhart in 1954 from West Bantam.

The lichen makes a thin, dull, greyish-white thallus.

It contains the secondary compound 5-O-microphyllinic acid, which is detectable using thin-layer chromatography; the specific epithet refers to the presence of this substance.