Gracilicutes

Gracilicutes (Latin: gracilis, slender, and cutis, skin, referring to the cell wall) is a taxon created by Cavalier-Smith, which he believes to be a clade comprising the Proteobacteria, the Planctobacteria (comprising Chlamydiae and Planctomycetes), the Sphingobacteria (comprising the green sulfur bacteria and Bacteroidetes), and Spirochaetae. It is a Gram-negative clade that branched off from other bacteria just before the evolutionary loss of the outer membrane or capsule, and just after the evolution of flagella.

	Escherichia coli cells magnified 25,000 times

	Cavalier-Smith's version of the tree of life, showing the subgroups of the clade Gracilicutes.