Abstract
A black yeast-like fungus was isolated from house dust in Hamamatsu, Shizuoka, Japan. It was compared with a culture derived from the neotype of Hortaea werneckii and 15 cultures isolated from patients with tinea nigra in Okinawa and identified as Hortaea werneckii. The colonies of the fungus were blcak, yaest-like and glossy on various kinds of agar media. Conidia were dark, elliptical, fusiform, or peanut-shaped, and one or two-celled. The septum of two-celled conidia was darker than their cell wall. Hyphae were light to dark brown, 3.5-5μm wide, and with many septa. Apical and lateral walls of hypha, which had small pegs with irregular frills, produced conidia. Both ends of two-celled conidia also produced conidia secondarily. The isolate hydrolyzed skim milk and showed a tolerance to salt and high osmotic tension. There have been several reports of tinea nigra in Okinawa and Kyusyu, southern parts of Japan. The present isolation of H. werneckii, however, shows the possibility of occurrence of the disease in Honsyu, the country's main island.
