Patterns of prespore differentiation across the Dictyostelid phylogeny. (A) Cells from 98 Dictyostelium species that make up most of all major groups and intermediate minor groups of the Dictyostelium phylogeny were developed to the mid and late sorogen stage and stained with spore specific antibodies. Staining patterns for three to four representatives of each major group or clade and for the group intermediate species are shown together with phase contrast images of the sorogens. The coloured borders of the images mark the group or clade to which the species belong, as outlined in the cladogram of the Dictyostelium phylogeny [13, 15] in panel B. Scale bars: 100 μm. (B) The relative contributions of stained prespore and unstained anterior and rearguard cross-section areas were measured in five sorogens for each species and the averaged fractions of each area are presented as stacked bars, with red bars representing prespore area and blue and green bars anterior and rearguard non-prespore areas, respectively. (C) The presence or absence of cellular support structures, such as the basal disc or the triangular supporter were retrieved from a recent comparison of species phenotypes . (D) Prespore staining patterns of a few species that were exceptions in their taxon group. White bars: 100 μm, pink bar 10 μm.