Trichophyton rubrum is the most common dermatophyte
associated with onychomycosis, others include
T. interdigitale, Epidermophyton floccosum, T. violaceum,
M. gypseum, T. tonsurans, T. soudanense (considered by
some to be an African variant of T. rubrum rather than a
full-fledged separate species) and the cattle ringworm
fungus, T. verrucosum.2 Note that T. interdigitale is still
sometimes referred to as T. mentagrophytes var. interdigitale.
The latter should be used to describe the zoophilic
form of the dermatophyte, and T. interdigitale used to
describe its anthropophilic form. Recent genetic research
has shown that T. mentagrophytes var. granulosum is the
same as T. interdigitale