Flora of New Zealand Series

Type : P. canina (L.) Willd. [=Lichen caninus L.]

Description : Flora (1985: 362).

Species of Peltigera are foliose, commonly broad-lobed lichens, having a cyanobacterial photobiont (and in some Northern Hemisphere taxa a green chlorococcoid photobiont), a corticate upper surface and an ecorticate lower surface with prominent veins and rhizines. It is the generitype of the family Peltigeraceae. Peltigera and its closest relatives are currently placed in the order Lecanorales as the suborder Peltigerineae, comprising four familes: Lobariaceae, Nephromataceae, Peltigeraceae and Placynthiaceae (Eriksson & Strand 1995; Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005). Peltigera is a widespread cosmopolitan genus with c. 70 species known worldwide (Galloway 2000c; Miadlikowska & Lutzoni 2000; Kirk et al. 2001; Martínez et al. 2003; Vitikainen 2004a). Species of Peltigera often have a well-developed secondary chemistry (Galloway 1991b; Vitikainen 1994b) and support a high diversity of lichenicolous taxa (Hawksworth 1980a; Vitikainen 1994b; Galloway 2000c). Species are fast-growing and often occur in disturbed habitats where their lifespan is short. Being potential diazotrophs (nitrogen-fixers), they undoubtedly make a positive contribution to the cycling of nitrogen in the biomes in which they occur. The contribution of species of Peltigera to the nitrogen budgets of forest, and grassland biomes in New Zealand is undoubtedly substantial, since many of the taxa have rapid growth, produce a large biomass, and appear to be strongly competitive. It is becoming clear that the ability of lichens to contribute to the nitrogen budgets of forest and grassland ecosystems on nitrogen-limited soils is a major ecological role for these symbiotic diazotrophs (Galloway 1995c). Carotenoids in species of Peltigera are discussed by Czeczuga et al. (2004).

The Flora account of Peltigera (Galloway 1985a: 362–366) discussed P. dolichorhiza, P. lepidophora, P. membranacea, P. nana, P. spuria [=P. didactyla], P. subhorizontalis and P. ulcerata. Recent Northern Hemisphere studies on Peltigera (Purvis et al. 1992; Holtan-Hartwig 1993; Vitikainen 1994a, 1994b, 2004a; Goffinet & Hastings 1994; Goward et al. 1995; Martinez et al. 1997, Miadlikowska & Lutzoni 2000; Goffinet et al. 2003; Miadlikowska et al. 2003) have considerably clarified the limits of taxa, and a more precise evaluation of chemical and morphological characters has led to a much clearer and more rigorous definition of species than was hitherto applied. In a detailed, phylogenetic revision of Peltigera (based on 46 Northern Hemisphere species), the monophyly of Peltigera (including Hydrothyria J.L.Russell) was confirmed, eight monophyletic sections were circumscribed, viz. Sect. Peltigera; Sect. Polydactylon Miadlikowska & Lutzoni; Sect. Chloropeltigera Gyeln.; Sect. Peltidea (Ach.) Vain.; Sect. Horizontales Miadlikowska & Lutzoni; Sect. Retifoveatae Miadlikowska & Lutzoni; Sect. Phlebia Wallr.; and Sect. Hydrothyriae Miadlikowska & Lutzoni, and the genus Hydrothyria was transferred to Peltigera. In the light of this recent work on the taxonomy and distribution of Peltigera in the Northern Hemisphere, a reappraisal of Peltigera in New Zealand disclosed 16 taxa (Galloway 2000c). Vitikainen (2004b) has recently clarified the application of two Gyelnik names based on New Zealand material.