Kuettlingeria is a genus of saxicolous (rock-dwelling), crustose lichens in the family Teloschistaceae. Species are characterized by a white or gray thallus and the presence of anthraquinones in the apothecial disc and true exciple, with the exception of Kuettlingeria diphyodes, which entirely lacks anthraquinones. First described by Italian botanist Trevisan in 1857, the genus includes 15 recognized species, although it is believed to be more diverse with additional unnamed species. These lichens are predominantly found in the Northern Hemisphere, particularly in the Mediterranean region, and grow on limestone and base-rich siliceous outcrops in sunlit conditions.
The thallus and thalline exciple of Kuettlingeria species are always without anthraquinones but contain the pigment Sedifolia-gray. The epihymenium and upper part of the true exciple usually contain anthraquinones, such as non-chlorinated parietin or chlorinated 7-Cl-emodin, fragilin, or 7-Cl-citreorosein. Sometimes, the epihymenium and true exciple contain both anthraquinones and Sedifolia-gray. In some species, two chemotypes are known within the same species—with red-coloured apothecia (with anthraquinones) and rarer with black-colored apothecia (without anthraquinones, only with Sedifolia-gray). Kuettlingeria diphyodes is the only exception in the group—the chemotype entirely without anthraquinones is only known.[3]
Habitat and distribution
Kuettlingeria species are found in the Northern Hemisphere, with a biodiversity centre in the Mediterranean region. They are also found in non-Mediterranean Europe, Asia, North America, and Macaronesia. One record is known from Ecuador (K. aff. soralifera, found growing on concrete). The genus consists exclusively of saxicolous (rock-dwelling) taxa, which grow on limestone and base-rich siliceous outcrops in sunlit conditions, mostly from sea coasts to the mid-altitudinal zone. A few species, such as K. diphyodes and occasionally K. atroflava, grow on rather acidic siliceous boulders in streams. Kuettlingeria percrocata is a single species confined to the montane–alpine zone.[3]
^Trevisan, V. (1857). "Nuovi studi sui licheni spettanti alle tribù delle Patellariee, Baeomycee e Lecideinee". Revista Periodica dei Lavori della Imperiale Regia Accademia di Padova (in Italian). 5: 63–79.
^ abcdFrolov, Ivan; Vondrák, Jan; Košnar, Jiří; Arup, Ulf (2020). "Phylogenetic relationships within Pyrenodesmia sensu lato and the role of pigments in its taxonomic interpretation". Journal of Systematics and Evolution. 59 (3): 454–474. doi:10.1111/jse.12717. S2CID234535735.