New observations on Erioderma in North America

For the three species of Erioderma occurring in North America ( E . mollissimum (Samp.) Du Rietz, E. pedicellatum (Hue) P. M. Jørg. and E. sorediatun D. Gall. & P. M. Jørg), considerable range extensions are being reported together with ecological information that will help to understand the distribution of these lichens. Erioderma sorediatum has been recently discovered in North America by Sherwood and Pike (unpubl.), while E. mollissimum and E. pedicellatum are reported as new to Nova Scotia herein along with a number of new localities for the latter species in Newfoundland. Ongoing work on E. pedicellatum and its symbionts has been summarized and an attempt has been made to outline its possible postglacial history. It is postulated that the presently known ranges have been occupied by the lichen only within the past few thousand years (more recently in Europe than in North America), and that considerable migrations must have taken place prior to that. This is NRCC publication No. 20463.