Abstract
This paper deals with the conidial ontogenesis of black yeasts such as E. jeanselmei, E. gougerotti, E. dermatitidis and E. spinifera and a discussion of their phylogenesis. Conidial ontogenesis of E. jeanselmei, E. gougerotii and E. dermatitidis were almost the same. One to five annellated tips were observed at the apices of conidiogenous cells, which were bottle- or jar-shaped, by scanning electron microscopy. Annellations on the tips looked like fringes. Namely, the conidiogenous cells of these three species were annellides. These annellated tips were formed on hyphae and annelloconidia were also produced from them in the same way. Occasionally, secondary annellides were formed from the primary ones. They looked like monile-form hyphae. A daughter conidium sometimes budded directly from a mother one. The shapes and sizes of the conidia of these three species were almost the same. Conidial ontogenesis of E. spinifera was also annellidic. However, an annellated tip was usually formed on an annellide. The annellated tips of the fungus were long and more than 20 annellations were observed on their walls. There were no differences in the biological examinations except KNO3 assimilation among these four species. The growth of E. jeanselmei and E. gougerotii was poor at 37°C. The GC contents of E. jeanselmei 1171, E. gougerotii CDC. B-1800, E. dermatitidis MM-7 and E. spinifera 2043 were 54.6, 54.6, 56.6 and 59.7%, respectively. The findings of the conidial ontogenesis and the results of the biological examinations and GC contents seem to suggest that these four species of Exophiala are related to basidiomycetous yeasts.
