The life cycle of Hortaea werneckii includes yeast-like, hyphal and meristematic growth. The preponderance of each form of propagation can be influenced by environmental conditions. The clinical entity 'tinea nigra' is explained by ecological similarities between supposed natural niches and human hyperhydrotic skin. The species is recognizable by assimilation of lactose, nitrate and nitrite, no or little growth with L-lysine, cadaverine, creatine and creatinine, and tolerance of 10% NaCl. It generally does not grow at 36 degrees C.