Setosphaeria Prolata, The Ascigerous State of Exserohilum Prolatum

Abstract

The new genus Exserohilum is established for species formerly included in Bipolaris (graminicolous Helminthosporium spp.) in which the conidial hilum is distinctly protuberant. The ascigerous states of Exserohilum spp. are placed in the new genus Setosphaeria, which is segregated from Keissleriella (= Trichometasphaeria) on the basis of lack of a clypeus, lysigenous development of the ostiole, occurrence of setae on the perithecial wall, the absence of periphyses in the ostiole, and the hyphomycetous conidial states. A new species, E. prolatum, and its ascigerous state, S. prolata, are described. Exserohilum prolatum was isolated from corn seed and leaves but is also pathogenic to several other gramineous species. It is heterothallic and produces ascocarps readily in culture. The following new combinations are made: Exserohilum rostratum (Drechs.) Leonard & Suggs, E. halodes (Drechs.) Leonard & Suggs, E. holmii (Luttrell) Leonard & Suggs, E. pedicellatum (Henry) Leonard & Suggs, E. monoceras (Drechs.) Leonard & Suggs, E. frumentaceum (Mitra) Leonard & Suggs, E. turcicum (Pass.) Leonard & Suggs, Setosphaeria holmii (Luttrell) Leonard & Suggs, S. pedicellata (Nelson) Leonard & Suggs, S. turcica (Luttrell) Leonard & Suggs.