The ultrastructure of the septal pore cap (SPC) of Asterodon, Asterostroma and Coltricia were examined to establish the taxonomic
position of these genera. Asterostroma has dolipores with perforate SPCs and is classified in the Lachnocladiaceae. In contrast,
Asterodon and Coltricia have dolipores with imperforate SPCs and belong to the Hymenochaetaceae. Other selected species of genera
belonging to the Hymenochaetaceae like Hydnochaete, Coltriciella, Inonotus, Onnia, and Cyclomyces also contained imperforate SPCs.
Coltriciella, Inonotus and Cyclomyces moreover presented a lamella of endoplasmic reticulum above the imperforate SPC after chemical
fixation. Such a lamella could rarely be observed in Coltricia only after high-pressure freezing and freeze substitution. Cryofixed
fungal cells of Cyclomyces and Coltricia showed differences in the architecture of the matrix of the SPC. Coltricia showed a more
layered matrix structure than the SPC of Cyclomyces. In addition, transmission- and scanning electron microscopy revealed an indent
in the centre of the imperforate SPC of Cyclomyces, indicating a reduced thickness, and resulting into a tented profile in cross-sections.