Acanthothecis aquilonia is a species of corticolous lichen in the family Graphidaceae, and was first described in 2008 by Alan Archer and John Alan Elix.[1] [2] The holotype (CANB 769685.1) was collected in Australia's Kakadu National Park from a tree trunk in lowland monsoon forest, on 10 August 2005 by Alan Archer.