Phytogeny and evolution of Caliciaceae, Mycocaliciaceae, and Sphinctrinaceae (Ascomycota), with notes on the evolution of the prototunicate ascus

Abstract

Small subunit ribosomal DNA has been sequenced from seven members of the ascomycete order Caliciales s.l. (Calicium adspersum, Cyphelium inquinans, Texosporium sancti-jacobi, and Thelomma mammosum (Caliciaceae), Chaenothecopsis savonica and Stenocybe pullatula (Mycocaliciaceae), and Sphinctrina turbinata (Sphinctrinaceae)), included in a matrix of 58 homologous ascomycete sequences and analysed with maximum parsimony analysis. The result shows the Caliciaceae to be a strongly supported monophyletic group within the Lecanorales s.l., although the jackknife support for a monophyletic Lecanorales is low. Mycocaliciaceae and Sphinctrinaceae form a well-supported monophyletic group, grouping with representatives of Eurotiales and Onygenales. This larger group is the sister group to Lecanorales, but the support for this sister-group relationship and the monophyly of the group consisting of Mycocaliciaceae–Sphinctrinaceae and Eurotiales–Onygenales is low. The evolution of the prototunicate ascus is discussed, and it is concluded that there is neither any evidence for a monophyletic Caliciales s.l., nor for the suggested group "Euascomycetideae" sensu Tehler, with the prototunicate Caliciales being the sister group to the rest of the true ascomycetes. Prototunicate asci are shown to have reappeared at least four times in the evolution of the ascomycetes. Key words: Ascomycetes, lichens, molecular evolution, phylogeny, ribosomal DNA, 18S rDNA.