He is a visiting professor at the Federal University of Mato Grosso do Sul in Campo Grande, Brazil. Because of Aptroot's broad expertise in tropical lichens, his colleague Ingvar Kärnefelt has called him "a Müller Argoviensis of our time". Aptroot is the author or co-author of three of the thirty most highly cited publications published in the scientific journal The Lichenologist from 2000 to 2019.
