Diorygma isidiolichexanthonicum is a species of corticolous (bark-dwelling), crustose lichen in the family Graphidaceae.

The type specimen was collected by the author from the Recanto das Nascentes Divina in Joinville (Santa Catarina); there, in the Atlantic Forest, it was found growing on tree bark.

The presence of isidia is somewhat rare in Diorygma;[1] D. australasicum and D. isidiatum are the only other members of the genus that have these reproductive propagules.

[1][3] Diorygma isidiolichexanthonicum is distinguished by its corticolous thallus, which is continuous, lacks a cortex, and has a dull, pale ochraceous colouration, with a thickness of up to 0.2 mm.

Soredia are absent in this species, but it features numerous isidia that cover the majority of the central thallus area.