chroococcales chroococcales the chroococcales (/ˌkroʊəˌkɒˈkeɪliːz/) are an order of cyanobacteria in some classifications which includes the harmful algal bloom microcystis aeruginosa. molecular data indicate that chroococcales may be polyphyletic, meaning its members may not all belong to the same clade or have the same common ancestor. chroococcales microcystis aeruginosa scientific classification domain: bacteria phylum: cyanobacteria class: cyanophyceae order: chroococcalesvon wettstein von westerheim families aphanothecaceae komárek et al. 2014 chroococcaceae nägeli cyanobacteriaceae komárek et al. 2014 cyanothrichaceae elenkin in kiselev entophysalidaceae geitler gomphosphaeriaceae elenkin microcystaceae elenkin stichosiphonaceae hoffmann, komárek, & kaštovský characteristics the order is characterized by single, floating cells or colonies which are embedded to a matrix. also, a lack of differentiation between apical and basal structures exists.