Thalli of Lobaria pulmonaria of different sizes were collected from the trunks of two specimens of Populus tremula. The secondary lichen compounds, stictic, constictic, norstictic, peristictic, cryptostictic and methyl stictic acid were quantified by HPLC and ranked in order of decreasing concentration. There was a highly significant positive correlation between thallus size and the total concentration of secondary compounds, as well as the total content per unit area for specimens from the two sampled trees. According to hypotheses inferring a herbivore deterrent role of secondary lichen compounds, small, juvenile thalli should be more susceptible to herbivores than larger thalli. Thus herbivory might limit survival of young specimens in habitats rich in lichen-feeding molluscs and thereby reduce reproductive success.

The potential spatial distributions of six epiphytic lichen species were assessed in Switzerland (41 000 km2) as a function of various key climatic drivers and forest types using logistic regression models. Cetrelia cetrarioides is ‘near threatened’, Lobaria pulmonaria is ‘vulnerable’, and Graphis scripta, Hypogymnia physodes, Lecanora cadubriae, Letharia vulpina are not endangered according to the Red List assessment based on IUCN criteria. Lichen presence and absence were derived from the SwissLichens database that contains spatially explicit information on both species presence and absence.

The spatial lichen niches are predicted with R2 values between 0·5 and 0·75 and AUC values between 0·63 and 0·94. Model evaluation shows that the models perform well.

Lichenologists reviewed the spatial predictions of lichen species on the basis of their expert knowledge and concluded that parsimonious regression models may suffice for successful prediction of the potential spatial niche distributions of epiphytic lichen species.

Argüello et al. (2007) found that Parmelina quercina, as circumscribed by Hale (1976), comprised four phylogenetic species which could also be distinguished by morphological features and also had different distributions: P. carporrhizans (usually rhizinate apothecia, and distinct effigurate maculae; oceanic Europe and Macaronesia), P. coleae (usually rhizinate apothecia, narrow ascospores, and fenestrate maculae; North America), P. elixia (non-rhizinate apothecia, larger ascospores, smaller conidia, and not or faintly maculate; Australia), and P. quercina (apothecia rhizinate or not, and less distinct more rounded maculae; continental Europe).

Lecidea fuscoatra (L.) Ach. is one of the earliest lichen species described, and is very common and widespread in Europe. Lecidea grisella Flörke, described from Germany, was kept separate at species level in many floras until the 1950s. In recent lichen floras, however, and in the most recent key to the genus (Hertel 1995), L. grisella is no longer accepted at species level, although it is keyed out and recognized by Hertel as L. fuscoatra var. grisella (Floerke) Nyl. The main difference is usually reported to be the thallus colour; brown and shiny in L. fuscoatra, grey and opaque in L. grisella. Some authors, for example Hertel (1995) and Wirth (1995), report that the two taxa have different habitat preferences: L. fuscoatra occurring mainly on acid substrata, while L. grisella is reported to prefer more neutral, often dust-impregnated rock and to be common on roof tiles.

The genus Xanthoparmelia (Vain.) Hale (including Neofuscelia Essl.) currently includes more than 800 species (Blanco et al. 2004, 2005), 21 of which have been recorded in the Iberian Peninsula (Llimona & Hladun 2001). During recent studies of the lichen flora of Castilla y León by the first author, a rare, loosely adnate or vagrant, terricolous Xanthoparmelia has been found at two localities in Burgos province. Although a collection (VAL-Lich 20080) from one of the localities (Fresnillo de las Dueñas) was previously reported as the American species X. vagans (Nyl.) Hale (Pérez-Ortega et al. 2002), this collection has now been redetermined as X. pseudohungarica (Gyeln.) Hale.

Hauck & Huneck (2007) and Hauck et al. (2007) established that lichen secondary chemistry is related to metal absorption in the apoplast of lichens. Depsidones occurring in the medulla of the Mn2+ and Cu2+-sensitive epiphytic lichen Hypogymnia physodes were found to reduce the absorption of Mn2+ and Cu2+ at cation exchange sites (Hauck & Huneck 2007). Several lichen substances, belonging to the depsidones, depsides, anthraquinones, or pulvinic acid derivatives, are known to absorb Fe3+ (Engstrom et al. 1980; Hauck et al. 2007). Occurrence of such lichen substances in lichens of Fe-poor sites, but rarity in lichens from Fe-rich sites suggests that they promote the intracellular uptake of Fe3+ (Hauck et al. 2007). In Acarosporion sinopicae lichens specialized on Fe-rich rock and slag, only two efficient Fe3+ absorbers are known, viz. the depsidone norstictic acid and the pulvinic acid derivative rhizocarpic acid. Their occurrence in Acarosporion sinopicae lichens is attributed to the fact that they reduce the absorption of Fe2+ at cation exchange sites despite their high affinity to Fe3+ (Hauck et al. 2007). The observations by Engstrom et al. (1980), Hauck & Huneck (2007) and Hauck et al. (2007), which were made in experiments with isolated lichen substances, suggest that these secondary metabolites control metal homeostasis in lichens by reducing the absorption of selected metal ions in the apoplast and by promoting the uptake of Fe3+.

In a recent treatment of the Pannariceae of Ecuador, Jørgensen & Arvidsson (2004: 131) pointed out the surprising absence of the genus Fuscopannaria in Ecuador, a genus which is rather common, with many species, in the Pacific Northwest of North America (Jørgensen 2001). The authors claim that, on the western side of the Americas, the genus appears to stop north of Mexico, only to reappear in southern Chile and Argentina. While going through his material, the second author discovered two specimens belonging in this genus from Mexico and Ecuador, which contradicts that statement. Both are typical Fuscopannaria leucosticta specimens (Fig. 1), the type species of the genus originally described from eastern North America (Jørgensen 2001: 684), and fairly widely distributed in warm temperate parts there, and extending as far south as Cuba (Fig. 2).