Erratomyces, a new genus of Tilletiales with species on Leguminosae

Abstract

In India and in the American tropics angular black spot disease on leaves of Vigna spp. and Phaseolus vulgaris (Fabaceae) is caused by Protomycopsis patelii and Entyloma vignae, respectively. According to a study of recently collected material from Nicaragua and of Indian herbarium specimens the two names are synonyms. The fungus is related to smut fungi of the genus Tilletia because it produces relatively large, opaque teliospores which have a partition layer in their wall and which germinate with holobasidia carrying needle-shaped basidiospores. It also has dolipores in the hyphal septa and ballistoconidia in culture. In contrast to species of Tilletia and related genera, the teliospores are scattered in intercellular spaces in the mesophyll without rupturing it and develop mostly intercalaryly. Additionally taking into account the distinct host family, the agent of angular black spot disease of beans cannot be classified in any known genus. The new genus Erratomyces is proposed. Further species of Protomycopsis described from India, namely P. ajmeriensis, P. crotalariae, P. smithiae, and P. thirumalacharii, belong to this new genus because they are also characterized by the production of leaf spots on Leguminosae, and have partition layers and dolipores. They are presented as new combinations in the new genus.