Cavernularia hultenii in Northernmost Newfoundland and Southern Labrador

Abstract

The range of Cavernularia hultenii in eastern North America extends as far north as southern Labrador (51940'N) and the northernmost tip of Newfoundland (51035'N). The habitats of C. hultenii are described. All share a highly humid microclimate. In northern Newfoundland, this apparently drought-sensitive lichen is most common near the east coast where the general climate is more favorable for the generation of suitable microhabitats. The first collections of Cavernularia hultenii Degel. in eastern North America were made by Ahti in the summer of 1956 from the Avalon and Burin Peninsulas of southeastern Newfoundland (Ahti 1959; Ahti & Henssen 1965). We are now able to report a number of new stations from the Northern Peninsula of Newfoundland and from southern Labrador that provide a considerable range extension northward for this oceanic element in the boreal lichen flora of eastern Canada. In addition, two thalli of C. hultenii in one of the northernmost localities (near Raleigh) were found to have numerous galls on them, resembling those reported on C. hultenii near Fort Louisbourg, Nova Scotia (Maass & Rice 1982). Cavernularia hultenii is a sorediate species that is expected to spread effectively into all available suitable habitats by its small vegetative propagules. Its substrate specificity is exceedingly low (Maass 1981). Therefore, the presently known distribution of this predominantly coastal lichen largely reflects the microclimate in its habitats and the travelling routes of observant botanists (see Fig. 1). In Nova Scotia, C. hultenii is only found within a narrow strip to 1-2 km inland from the shore of the Atlantic Ocean. It is conspicuously absent from the coastlands of the Bay of Fundy and Northumberland Straits with their warmer climates, as well as from industrial areas that over the years have received a considerable amount of air pollution (Maass 1981). The overall distribution and ecology of C. hultenii are of considerable interest because of its present narrow range, which includes small areas in Scandinavia (Degelius 1952), Scotland (Swinscow 1960) and western North America (Ahti & Henssen 1965) as well as Nova Scotia (Maass 1981). Its frequency in northernmost Newfoundland and southern Labrador (Fig. 1) suggests that C. hultenii may possibly also occupy the easternmost edge