Genus Serusiauxia was established by Damien Ertz and Paul Diederich in 2020 to accommodate a unique species within the family Pyrenulaceae.

The type specimen was collected by Diederich from the Sir Seewoosagur Ramgoolam Botanical Garden (Pamplemousses District, Mauritius), at an elevation of 80 m (260 ft), where it was found growing on a more or less vertical trunk of a Terminalia tree.

The genus is distinguished from other genera in the Pyrenulaceae by its chemical composition, specifically the C+ (red) soralia reaction due to gyrophoric acid.

[2] The genus is named in honour of Emmanuël Sérusiaux, recognising his significant contributions to the field of lichenology, particularly in tropical regions.

Serusiauxia and Lithothelium septemseptatum form a distinct clade, separate from Pyrenula (in the strict sense) and Anthracothecium, indicating significant genetic divergence.

Additionally, Dendrographa decolorans is found mainly in Mediterranean and temperate regions and belongs to a different phylogenetic group (Arthoniomycetes, Roccellaceae).

[2] Syncesia myrticola (sorediate morphs): This species differs chemically by containing protocetraric acid, with a thallus that reacts PD+ (rust-red).