Calogaya arnoldii is a species of saxicolous (rock-dwelling), crustose lichen that is common and widespread in Europe and Asia.

Molecular phylogenetic studies showed Caloplaca to be polyphyletic, and it was divided up into several smaller genera in 2013.

[5] The lichen is part of a species complex with complicated taxonomy, and in which intermediate phenotypes are frequently observed, making it difficult to reliably distinguish them.

[6] Calogaya saxicola is one such similar species, and it has often been confused with C, arnoldii in areas where they co-occur, as the differences between them are subtle.

[7] Verrucula arnoldaria is a lichenicolous lichen that parasitises Calogaya arnoldii.