Abstract
Summary Molecular signatures of new, as yet uncultured mollicute‐like organisms (MLOs) have been detected in total rRNA and DNA extracted from tissues, gut contents and casts of four species of the earthworm family Lumbricidae. The MLO 16S rRNA sequences exhibited low identity to those of known Mollicutes species and formed a monophyletic cluster distantly affiliated to the ‘ Candidatus Bacilloplasma’ (84.9%) and almost equidistant to the other main phylogenetic group of Mollicutes ( Bacilli ( Clostridia ( in situ hybridization (FISH) analysis with a nucleotide probe specific for the new MLO group localized them to the coelomic fluids of earthworms. A new taxonomic group within the Mollicutes , designated ‘ Candidatus Lumbricincola’, is proposed to include these as yet uncultured organisms.