Kudratovia
Kudratovia is a genus of lichen-forming fungi in the family Physciaceae. The genus was established in 2021 based on molecular evidence showing that several species previously placed in Rinodina and related genera form a distinct evolutionary lineage. Species in this group typically grow as whitish to grey crusts on limestone and other calcium-rich rocks in harsh environments such as arctic tundra, high mountains, and arid regions. The genus includes eight species distributed mainly across the Northern Hemisphere, particularly in Eurasia and arctic regions.
Taxonomy
Kudratovia was introduced in 2021 by Sergey Kondratyuk and co-authors as part of a broad molecular reassessment of the family Physciaceae. The genus was erected for a well-supported monophyletic branch that had previously been treated within Rinodina and allied genera, and is typified by Kudratovia straussii. Eight species were transferred to the new genus; under their original combinations they had been placed variously in Rinodina, Buellia and Lecanora.Molecular phylogenetic analyses place Kudratovia within the "Phaeophyscia s. l." subclade of the Physciaceae, rather than with Rinodina in the strict sense. In trees inferred from ITS sequences alone the Kudratovia clade is sister to the Oxnerella and Rinodinella lineages, whereas in the combined dataset it nests in the Phaeophyscia-centred assemblage. Within the genus two main species groups are recognised: a K. straussii group and a K. roscida group comprising the fertile K. roscida and the sorediate K. candidogrisea, which form a closely related. The transfer of these taxa to Kudratovia also resolved several earlier GenBank records where sequences filed under names such as "Rinodina lecanorina" were shown to belong to K. luridata. Kondratyuk and colleagues' division of Rinodina into smaller segregate genera has not been accepted by all taxonomists.
Description
Species of Kudratovia have a crustose thallus that ranges from thin and largely to more conspicuous, crusts. The thallus is usually to and may be or weakly towards the margins. Colours are typically whitish to grey, sometimes becoming slightly yellowish or brownish, and some species develop a powdery or crystalline on the thallus surface. In section, the has a structure, while the medulla is often indistinct and may contain crystals of calcium oxalate.Apothecia are in form, with a rim formed by the surrounding thallus; in some specimens this becomes reduced with age. The may be pruinose or non-pruinose. Ascospores are of Bicincta- or Physcia-type within the Physciaceae spore terminology, and in K. terrestris they may show elongate, hyaline ends. Conidia are and rod-shaped. Chemically, the thallus commonly contains the triterpenoid compound zeorin in varying amounts, sometimes accompanied by small quantities of variolaric acid and at least one unidentified fatty acid; in some specimens no lichen substances are detectable by thin-layer chromatography.
Habitat and distribution
Kudratovia species grow predominantly on calcareous substrates. They are most often found on carbonate rocks, including calcareous sandstone, but may also occur over moss cushions or plant litter and, more rarely, directly on calcium-rich soil. The genus is associated with relatively harsh environments, especially arid regions and high-elevation alpine settings, where its species colonise exposed mineral surfaces.The genus comprises eight species with mainly Holarctic and Eurasian distributions. Kudratovia roscida is widespread in arctic and alpine ecosystems across the Northern Hemisphere, whereas K. straussii and K. luridata are so far known from mountain regions of Eurasia. Several species appear to be confined to Asia, including K. bohlinii, K. pycnocarpa and K. terrestris, while K. candidogrisea is reported from the Alps as a sorediate counterpart of K. roscida.
Species
, eight species are accepted in Kudratovia:Kudratovia bohlinii Kudratovia candidogrisea Kudratovia luridata Kudratovia metaboliza Kudratovia pycnocarpa Kudratovia roscida Kudratovia straussii- ''Kudratovia terrestris''