New records of nail and skin infection due to Onychocola canadensis and description of its teleomorph Arachnomyces nodosetosus sp. nov.

Non-dermatophytic fungi are increasingly being recognized as agents of onychomycosis. In 1990, three cases of chronic infection of the great toenail in adult female residents of Canada were attributed to Onychocola canadensis, a previously unknown hyphomycete. Three additional cases were suspicious but unconfirmed. This report documents seven new records, including six of toenail infection in elderly individuals and one case of glabrous skin infection. Three isolations from New Zealand represent the first report of O. canadensis outside Canada. Treatment with griseofulvin in one New Zealand hallux infection case was found to improve the appearance of the nail, but specimens were culture positive after 6 months. The development in culture of broad, brown, nodose, thick-walled hyphae suggested an affinity to the ascomycete genus Arachnomyces. Although mating experiments were attempted on several different media, ascocarps were produced in six mated pairs on sterilized rice grains or rice extract agar after 7-12 months incubation. Arachnomyces nodosetosus Sigler & Abbott sp. nov. is described and compared with Arachnomyces minimus Malloch & Cain, also rarely isolated from cutaneous specimens. The genus Arachnomyces is placed in the Gymnoascaceae (Onygenales).