The genus Acanthostigma (Tubeufiaceae, Pleosporales)

The genus Acanthostigma is redescribed on the basis of the re-examination o f type material of A. perpusillum, type species of the genus. It is placed in the Tubeufiaceae and is characterized by having dark, setose ascomata, c ellular pseudoparaphyses, bitunicate asci, hyaline, multiseptate, cylindric al-fusiform to elongate fusiform ascospores. Helicosporium and Helicomyces anamorphs and occurrence on rotten wood or on stromata of other ascomycetes . Six species are accepted in Acanthostigma. Acanthostigma ellisii, A. long isporum, A. perpusillum, A. revocatum. A. minutum and A. scopulum are redes cribed and illustrated on the basis of re-examination of type material. A n ew combination for A. longisporum is proposed. A kev to species in Acanthos tigma is provided. Acanthostigma filisporum is excluded and its affinity to the Niessliaceae is discussed. Acanthostigmina is relegated to synonymy wi th Acanthostigma. Two species previously referred to Acanthostigmina and on e to Tubeufia sect. Acanthostigmina are not accepted in Acanthostigma and a re transferred to Taphrophila in the Tubeufiaceae and proposed as three new combinations T. hebridensis, T. miscanthi and T. trichella.