candidatus arthromitus candidatus arthromitus candidatus arthromitus is a group of morphologically distinct filamentous bacteria found almost exclusively in terrestrial arthropods. they were first discovered in the guts of insects by joseph leidy. despite their morphological similarity to candidatus savagella or segmented filamentous bacteria, they form a distinct lineage within the lachnospiraceae. arthromitus scientific classification domain: bacteria phylum: bacillota class: clostridia order: clostridiales family: clostridiaceae genus: candidatus arthromitus history