Arbuscular mycorrhizal fungi (AMF) occur in the majority of terrestrial, and some aquatic, habitats worldwide. They are important for the functioning of individual plants and of entire ecosystems. Here, we review trends in research on species-(species recognition, phylogenetic relationships, autecology) and community-level AMF diversity patterns and aim to identify ways of improving the complementarity of these approaches. Research into many aspects of AMF diversity has flourished in parallel with the increasing availability of molecular biology techniques. However, despite their shared goal of understanding AMF biodiversity, species- and community-level perspectives, and the morphological and molecular approaches that underpin them, currently have limited capacity for information exchange. We indicate critical research gaps in AMF species and community characterisation and outline important research directions. We propose steps that could link research using different methods and targeting different aspects of diversity, in order to maximise our understanding of AMF. (C) 2016 Elsevier Ltd and British Mycological Society. All rights reserved.