A Scanning electron microscopy (SEM) micrographs of the four airborne microalgae in the early stationary phase. Upper panel, left and right: Scenedesmus sp. DSA1 and Coelastrella sp. DSA2. Lower panel, left and right: Coelastrella sp. DSA3 and Desmodesmus sp. DSA6. B Phylogenetic analysis of the four airborne microalgal strains (underlined) and their related species based on the fusion sequences of ITS1 and ITS2 of each species. The numbers in the parentheses are accession numbers of each sequence in GenBank. The numbers at the nodes indicate bootstrap values (expressed as percentage) with 500 replicates.