The Order Asellariales is a group of fungi within the subphylum Kickxellomycotina (phylum Zygomycota), comprising approximately 12 described species. These fungi are obligate endosymbionts, primarily inhabiting the hindguts of terrestrial arthropods such as isopods (Isopoda) and springtails (Collembola). The thalli of Asellariales are septate and extensively branched, with a specialized basal cell that anchors them to the host's gut lining. Reproduction is asexual, occurring through the fragmentation of the thallus into uninucleate arthrospores.