Taxonomic divergence of the green naked-stipe members of the genus Microglossum (Helotiales).

Four new species of the Ascomycete genus Microglossum are recognized, based on morphological characters and DNA sequences of nuc rDNA (ITS region and 28S gene) and the second largest subunit of RNA polymerase II (RPB2). They differ from Microglossum nudipes by the color of the ascocarps and the sizes and shapes of ascospores, asci, and paraphyses. A lectotype is proposed, and an emended description is provided for M. nudipes. Descriptions of new species Microglossum clavatum, M. truncatum, M. pretense, and M. tenebrosum are provided. Other closely related species in the group of green earth tongues include Microglossum viride, M. rickii, and M. griseoviride. An identification key to green Microglossum species is presented.