Cyathus - Infrageneric Classification - Phylogenetic Analysis

Phylogenetic Analysis

The 2007 publication of phylogenetic analyses of DNA sequence data of numerous Cyathus species has cast doubt on the validity of the morphology-based infrageneric classifications described by Brodie. This research suggests that Cyathus species can be grouped into three genetically related clades:

ollum group: C. africanus (type), C. africanus f. latisporus, C. conlensoi, C. griseocarpus, C. guandishanensis, C. hookeri, C. jiayuguanensis, C. olla, C. olla f. anglicus, and C. olla f. brodiensis.

striatum group: C. annulatus, C. crassimurus, C. helenae, C. poeppigii, C. renwei, C. setosus, C. stercoreus, and C. triplex.

pallidum group: C. berkeleyanus, C. olla f. lanatus, C. gansuensis, and C. pallidus.

This analysis shows that rather than fruit body structure, spore size is generally a more reliable character for segregating species groups in Cyathus. For example, species in the ollum clade all have spore lengths less than 15 µm, while all members of the pallidum group have lengths greater than 15 µm; the striatum group, however, cannot be distinguished from the pallidum group by spore size alone. Two characteristics are most suited for distinguishing members of the ollum group from the pallidum group: the thickness of the hair layer on the peridium surface, and the outline of the fruit bodies. The tomentum of Pallidum species is thick, like felt, and typically aggregates into clumps of shaggy or woolly hair. Their crucible-shaped fruit bodies do not have a clearly differentiated stipe. The exoperidium of Ollum species, in comparison, has a thin tomentum of fine hairs; fruit bodies are funnel-shaped and have either a constricted base or a distinct stipe.