ASCOMA ONTOGENY - IS THIS CHARACTER SET OF ANY USE IN THE SYSTEMATICSOF LICHENIZED ASCOMYCETES

The use of ascoma ontogeny in the systematics of lichenized ascomycete s is reviewed briefly. Two recently studied examples are discussed to illustrate the use of ontogenetic studies to discover phylogenetic rel ationships. As one example, the Agyriaceae was mainly circumscribed by the ascus type and included diverse genera. Xylographa is characteriz ed by lirelliform apothecia. However, the ascoma development shares th e ontogenetic pattern observed in Trapelia and its placement in the fa mily was confirmed. Tn contrast, Anamylopsora exhibited a substantiall y different apothecial development and was separated as a family of it s own. As a second example, the Candelariaceae is based on chemical ch aracters. With the detection of pulvinic acid derivatives also in the genus Lecanora, the distinction of the Candelariaceae and Lecanoraceae ae became doubtful. Therefore, the ascoma ontogeny was employed to ev aluate this classification and is illustrated here in detail for Cande laria fibrosa. The substantial similarity of the ascoma development fo und in both families suggests that both might be better united. Finall y, a general discussion of the significance of ontogenetic characters in lichen taxonomy is included. (C) 1998 The British Lichen Society.