Comparative studies of the distribution and ecology of some oceanic species in the genus Leptogium (Lecanorales, Ascomycotina) in Norway
Dispersal strategy, ecology, and history are important factors controlling the distribution of Leptogium burgessii, L. cochleatum, L. cyanescens, and L. hibernicum in Norway. There was no correlation between the size of the diaspores and the geographical range. It is suggested for the first time that the "pearl-string hairy tomentum" in the Leptogium species might function as diaspores ("thalloconidia"). It seems that species with isidia have fewer dispersal strategy problems within the locality than those with spores and/or "thalloconidia". There is a relationship between niche width and geographical distribution, and between anatomy and morphology and water relations in the species. The distribution patterns suggest that L. burgessii, L. cochleatum, and L. hibernicum are likely to have been spread from the British Isles by long-distance dispersal, while L. cyanescens could also have been spread gradually to south-west Norway from the Oslo area. The "thalloconidia" may be important for the long distance dispersal of L. burgessii and L. hibernicum.