REEB, VALERIE C.*, CLAUDE ROUX, AND FRANCOIS M. LUTZONI. University of Illinois at Chicago, Department of Biological Sciences (M/C 006), 845W Taylor Street, Chicago IL 60607. The Field Museum, Department of Botany, 1400S Roosevelt Road, Chicago IL 60605. Faculté des Sciences et Techniques de St-Jérôme, Institut Méditerranéen d'Écologie et de Paléoécologie, case 461, Av. Escadrille Normandie Niemen, F-13397 Marseille Cedex 20, France. - A phylogenetic study of the Acarospora and Acarosporaceae (lichen-forming ascomycetes) and their position within the ascomycetes.
.
The genus Acarospora and the family Acarosporaceae are among
the most complex and poorly known lichen-forming ascomycetes.
Cryptolecanorine apothecia and multiple post-meiotic mitoses resulting
in polyspory are features that characterize the family. Because many
characters are cryptic or are highly variable within
Acarospora, their classification at almost all levels (species
to order) is very unstable. Preliminary DNA sequence data revealed
that Acarospora is among the basal members of the
"Lecanoromycotina". This basal phylogenetic position renders
it of particular importance for understanding the evolution of the
majority of lichenized ascomycetes. We will report on results from
phylogenetic analyses of SSU nrDNA, LSU nrDNA, and ITS sequence data
and present evidence for a re-circumscription of Acarospora. We
will test for monophyly of the yellow (subgenus Xanthothallia)
and brown (subgenus Phaeothallia) Acarospora and suggest
approaches for achieving a new and stable classification for
Acarosporaceae.
Key words: Acarospora, Acarosporaceae, phylogeny, ribosomal RNA