1. Duke University; Department of Biology; PO Box 90338 Durham, North Carolina 27708 USA
2. Université Catholique de Louvain; Unité d'Ecologie et Biogéographie; 4-5 Place Croix du Sud B-1348 Louvain-la-Neuve Belgium
3. Swedish Museum of Natural History; Department of Cryptogamic Botany; Box 50007 S-104 05 Stockholm Sweden