The recent discovery of Leptogium hibernicum Mitch. ex P. M. Jørg. in an eastern white cedar swamp in south-western Nova Scotia, Canada, represents the first report of this species on the North American continent. Considered rare in Norway (Jørgensen Reference Jørgensen2007) and Great Britain (M. R. D. Seaward, pers. comm), and of restricted distribution in the southern Mediterranean (Aragón et al. Reference Aragón, Otálora and Mártinez2005), it is known also from the West Indies, central South America, southern Africa and New Guinea (Jørgensen Reference Jørgensen1997). It appears to be among the rare amphiatlantic cyanolichens that include such species as Erioderma pedicellatum (Hue) P. M. Jørg. and E. mollissimum (Samp.) Du Rietz.
The cedar swamp (dominated by Thuja occidentalis L.) is located near Hectanooga, Digby County at an elevation of approximately 25m, and is approximately 12 km from the Bay of Fundy. The Bay of Fundy coast is among the foggiest in the world, with 90–120 days having periods of fog lasting more than one hour (Clayden Reference Clayden, McAlpine and Smith2010). This is consistent with the oceanic distribution known elsewhere for this species (Jørgensen Reference Jørgensen2007).
The distribution of Thuja occidentalis is scattered in Nova Scotia, and the Hectanooga stand is the largest, consisting of approximately 110 hectares. Leptogium hibernicum was found at three locations in the swamp on Acer rubrum. Other tree species in the swamp include Abies balsamea, Fraxinus americana, and Betula allegheniensis. Understorey shrubs include Ilex verticellata, Rhododendron canadensis, Amelanchier spp, and Viburnum nudum. Herbaceous species include Osmunda cinnamomea, O. regalis, Thalictrum pubescens, Vaccinium angustifolium, and Aralia nudicaulis. Other epiphytic cyanolichens such as Fuscopannaria leucosticta (Tuck.) P. M. Jørg., F. ahlneri (P. M. Jørg.) P. M. Jørg., Leptogium millegranum Sierk, and Erioderma mollissimum, are found in the cedar swamp.
Other Leptogium species with tomentum on the lower surface found in Nova Scotia include L. laceroides (B. de Lesd.) P. M. Jørg., L. saturninum (Dicks.) Nyl. and L. hirsutum Sierk, but none of these species have the dense striations or isidia with collapsed apices present on L. hibernicum. Leptogium hibernicum differs from L. pseudofurfuraceum P.M.Jørg. & Wallace known from the south-western United States (Brodo et al. Reference Brodo, Sharnoff and Sharnoff2001; Jørgensen & Nash Reference Jørgensen, Nash, Nash, Ryan, Diederich, Gries and Bungartz2004) and the west coast of Canada (Sierk Reference Sierk1964), as L. furfuraceum) in having a shorter tomentum (up to 22 μm) composed of globose cells. The tomentum of L. pseudofurfuraceum grows to 1mm and its cortical cells are larger, 5–9 μm rather than 5 μm or less.
Specimens examined. Canada: Nova Scotia: Digby Co, Hectanooga cedar swamp, 44° 08 N, 66°04 W, on Acer rubrum, 2009, Neily 63, Clapp 19, Anderson 150464 (NSPM).
The authors express their gratitude to P. M. Jørgensen for confirming the identity of the specimen of L. hibernicum and to anonymous reviewers for improvements to the manuscript.
