A mysterious new disease has been discovered. The pathogen responsible for the disease can be easily viewed on a light microscope using a 4x objective with 10x ocular lenses. Studies reveal that the pathogen easily desiccates, moves by changing the consistency of its cytoplasm, and it does not contain peptidoglycan [pep-Tl-doh-GLY-kuhn]. In which of the following groups will this pathogen likely be classified?