Soil biota in a megadiverse country: Current knowledge and future research directions in South Africa

•We comprehensively reviewed the present taxonomic knowledge of soil biota of South Africa.•South Africa contains nearly 2% of the world’s described species, with a high level of endemism.•Areas such as the Nama-Karoo, Northern Cape and Eastern Cape are undersampled for most taxa.•A more integrative approach to acquiring foundational knowledge of soil biodiversity is needed.