Usnea jørgenseniana Bystr. & Leśniewska sp. nova Usnea (subgen. Usnea, Parmeliaceae) in Sweden

Usnea jørgenseniana Bystr. & Leśniewska sp. nova , an epixilic species of bushy Usnea ( Par-meliaceae ) in Sweden, is similar to U. hirta var. minutissima (Mer.) Bystr., but the similarity to U. hirta is apparent. U. jørgenseniana is not a species from the foveatae Mot. section. The lack of soralia and a very small thallus (0.3–2.0 cm) makes it difficult to locate U. jørgenseniana in the section Comosae Mot. It colonizes exceptionally unfavorable climatic conditions, a coprophilous species. Collected by G. Ohrstedt in 1937. Dozens of specimens from one position.


INTRODUCTION
Lichens are one of the main links in the chain of matter and energy in nature.They actively participate in the circulation of gaseous atmospheric water, and this process is correlated with diurnal changes in relative humidity and temperature.
The complicated submicroscopic structure of the thallus surface enables the lichen fungus to take atmospheric organic nitrogen residues.The independence from the soil resources of water and organic substances allows them to colonize pioneer primary and secondary habitats.Essential carbohydrates provide a symbiotic photobiont.
Lichens are bioindicators of atmospheric pollution.Bryoria, Evernia divaricata and numerous Usnea species are indicators of naturalness of forests and mature forest ecosystems.Species from the families Parmeliaceae and Usneaceae are significant components of the landscape in forest communities.

U M C S
Despite the fact that in the recent decade much attention has been paid to lichens, the interest in this group is still not as big as in other groups of organisms.One of the reasons is the small economic importance of lichens, especially in the production of material goods.Sometimes they are removed from wood and old wooden fences as they are considered not aesthetic.The presence of large species on the treetops is interpreted differently.Trees covered by thalli are eliminated during the first selection of tree stands in forest corps.The presence of lichens on tree branches, especially large-branched species (macrolichenes), is interpreted differently.In forest crops, trees overgrown with lichens are eliminated during the first selection of stands.
In the forest areas of Eurasia there are several dozen bushy species of Usnea.They colonize bark, living and withered branches of trees.Shrubby Usnea species colonizing young as well as withered branches of trees, live shortly.Their lifespan does not exceed 5 years.Usually they are eliminated by self-cleaning of the tree crowns.The species which colonize rotting wood of farm buildings and other wooden structures, are nitrophilic and coprophilic (ornithocoprophy).They are eliminatrd only by human activity.
Usnea jørgenseniana Bystr.& Leśniewska is one of the few species of Usnea that colonizes only rotting constructions of wooden farm buildings.

MATERIALS AND METhODS
Specimens of the genus Usnea were collected mainly by amateur collectors and researchers of the regional lichen biota.The Usnea hirta Lublin herbarium collection is probably one of the largest collections of this species, most often several species (sometimes species of several genera) include specimens cited in lichenum generis Usnea.Studium monographicum Motyka (18), specimens identified by Bystrek (5), specimens published in regional publications (4,7), and specimens that have not been published, collected by students.It is highly probable that the collection contains taxa which are new to our knowledge.Dozens of specimens were collected 80 years ago (1937) by G. Ohrstedt from the wooden wall of the house, Jämtland: pa vaag and Rossbol Lockne; on 13 th September, 1937.Over 100 specimens were collected from one old board, probably a wooden fence of the property.
The specimens were identified as Usnea hirta subsp.epiphytica Bystr.and prepared for distribution as exsiccata.During the preparation of the samples, scientists had discovered that the similarity to Usnea hirta was apparent.After detailed research they discovered that it was a new species for science.
Sections for anatomical research of the thallus were made by hand with a razor blade and on permanent paraffin preparations [described by Leśniewska et -5.The herbarium specimens of Usnea jørgenseniana.Bar = 1 cm.Fig. 5a.Base of the thallus on the wood (magnified part of Fig. 5).Diagnosis: Morphology (Figs. [1][2][3][4][5][6][7][8][9][10]15): The surface of the thallus is smooth.Thallus shrubby 0.3-2 cm, grey-green; branches of various thicknesses, cylindrical, anisotomically branched growing out of one base.The main single branches, higher anisotomically branched, irregularly distorted and bent, the side branches are very numerous, straight and irregularly bent and branched, ending with numerous isidias of length up to several millimeters.Anatomy: Cortex formed by hyphae of the fungus perpendicular to the axis, glued with interfacial jelly (Tabs.III and IV); irregularly thick, in some places thin, membranous, in others thick; transversely or irregularly cracked), flaky, which means that sometimes the main branches are without bark.

Usnea jørgenseniana
Medulla white, of various thickness, plectenchymatic.Eukaryote photobiont (probably Trebouxia) placed in medulla under cortex.Photobionts cells of the examined cross-sections are green, also on paraffin preparations.
Usnea jørgenseniana Bystr.& Leśniewska is similar to U. hirta var.minutissima (Mer.)Bystr.; the similarity to U. hirta is not obvious.U. jørgenseniana is not a species from the foveatae Mot.section.The lack of soralia and very small thallus make it difficult to locate U. jørgenseniana in the Comosae Mot.section.
U. jørgenseniana differs from U. hirta in several diagnostic features.The thallus of U. hirta is attached to the substratum with a delicate, narrowed base, the axis is very thin; medulla is loose, cortex thin, membranous, does not flake off, does not fall off the lobes.The cortex and medulla do not stain from K, C, and KC.U. jørgenseniana has the base widened and firmly connected to the substratum, axis thick (Tab.I, Figs.: 5, 5a) rigid, glassy.The cortex of U. jørgenseniana is uneven in thickness, flakes off and on older branches falls off.In some specimens, the supramundane part of the thallus is devoid of cortex.
U. diplotypus Vain.Branches of uneven thickness, irregularly swollen, apical parts often sinuous; soralia punctiform and usually not expanding, soredia farinose, bearing relatively tall isidia; contains salazinic acid (main substance) and accessory substances.It colonizes silicate rocks: cortex thin; medulla variable both in density and thickness.
U. jørgenseniana differs from the U. monstruosa Vain.A distinct part of the basal thallus and lack of soralia.
U. compacta Mot. has a clearly distinguished basal part, but the branchets are cylindrical, with numerous warts and numerous sorves.U. lapponica Vain.Branches may have foveolae or depressions.Apical parts not characteristically twisted; soralia crowded or not, may become deeply concave when mature, and totally surround the terminal branches.
U. cornuta Koerb.The thallus clearly shrubby; soralia (and isidia) are concentrated at branch tips, becoming confluent, Secondary branches not clearly constricted at the base, being more or less uniform in diameter; consistency of medulla various.
U. hirta is a very common species, colonizing wooden structures and trees, easy to recognize.It is a species reported in regional floristic works.There are numerous specimens of this species in each herbarium.It is a variable species, several varieties have been described by Bystrek (5), halonen and Puolasmaa (14), Motyka (18).In the specimens known to us such as U. hirta in the LBL herbarium there were no specimens staining with KOh.halonen et al. (13,14), Scandinavian specimens of U. hirta are well.Among the specimens of U. hirta from Fennoscandia, halonen and Puolasmaa (14) there were found specimens staining with KOh.They are cited by Thell et al. (20).Perhaps these are specimens of U. jørgenseniana.

CONCLUSION
The assessment of the rank of the taxon in this group of species will always be debatable and depend on the researcher's knowledge.The paper does not finish the work.It organizes the materials under study.

DEDICATION
The name of the species is dedicated to professor Dr. J.M. Jørgensen.Professor J.M. Jørgensen is a lichenologist with rich scientific achievements, and an outstanding taxonomist. he is the author of several taxonomic monographs. he has described numerous new species from various systematic groups.he is a scholar who thoroughly evaluates the scientific achievements of others.