On the characterization and rank assignment criteria for the anaerobic gut fungi (Neocallimastigomycota)

Within a specific lineage, establishing a solid taxonomic framework is crucial for enabling discovery and documentation efforts, ensuring effective communication between scientists as well as reproducibility of results between laboratories, and facilitating exchange and preservation of biological material. Such framework could only be achieved by establishing clear criteria for taxa characterization and rank assignment. Within the anaerobic gut fungi (Phylum Neocallimastigomycota), the need for such criteria is especially vital, given the difficulties associated with their isolation, maintenance, and long-term storage, resulting in the unavailability and loss of previously described taxa. To this end, we here provide a list of morphological, microscopic, phylogenetic, and phenotypic criteria for assessment and documentation when characterizing newly obtained Neocallimastigomycota isolates. We also suggest a polyphasic rank-assignment scheme for novel genus, species, and strain level designations for newly obtained Neocallimastigomycota isolates.