Abstract
Keratinomyces ceretanicus was described as a new taxon distinct from Trichophyton ajelloi. Because of the morphological similarity between the two species, their mating behaviour was studied. The optimum temperature for growth of K. ceretanicus was found to be 25°C rather than 17°C. The type culture produced moderate numbers of microconidia on potato glucose agar after 2 weeks at 25°C and a large number of smooth, thick-walled, cylindro-fusiform, 7-to 12-celled macroconidia. On Sabouraud glucose agar containing chloramphenicol and cycloheximide growth was partially but not completely inhibited. When crossed on a soil-hair medium, K. ceretanicus produced fertile gymnothecia typical of Arthroderma uncinatum with 10 (−) mating type isolates of A. uncinatum. As a result, it is concluded that K. ceretanicus is a facultative synonym of T. ajelloi.