Transmission electron micrographs of Gastromyxum rafii n. sp. Spores have a single nucleus (n) and valves that interlock at the apical ends with a substantial overlap (a). The overlapping valves form a complex double layer, around parts of the polar capsule (b), which is not present at the apex of the polar capsule where the polar filament is discharged (asterisk) (c). Away from the apical ends of the spore, the vales meet to form a hinge-like structure (arrow) (d and inset). Scale bars 1 μm.