Erioderma mollissimum is a rare cyanolichen found on the foggy Atlantic coast of Canada. The rarity of E. mollissimum and the potential threat from human impact has led to conservation concern for this species in Canada. Recent finds on the island of Newfoundland suggest that the distribution of E. mollissimum may be wider than historically known. In order to better understand the environmental factors affecting distribution and to direct future search efforts a Mahalanobis predictive distribution model using a geographical information system (GIS) was developed for Atlantic Canada. The model suggests that only a small part of this region is suitable for E. mollissimum. This study provides an example of an alternative modeling technique to the traditional statistical methods for predicting lichen distribution.