Rinodina degeliana: a corticolous lichen species overlooked in Poland

New localities of Rinodina degeliana in Poland are described. The morphology, chemistry, distribution and ecology of the species are discussed and characters that help to differentiate R. degaliana from similar lichens are presented. The species is relatively frequent in lime-hornbeam forests of northern and central Poland.


INTRODUCTION
The genus Rinodina (Ach.)Gray was represented by 33 species, including 12 epiphytic species, in Poland (Fałtynowicz 2003).Two further taxa, R. griseosoralifera Coppins and R. degeliana Coppins, were reported by Czarnota and Kukwa (2007) and by Kukwa & Kubiak (2007), respectively.New localities of Rinodina degeliana Dedicated to Professor Barbara Gumińska on the occasion of her eighty-fifth birthday were recorded during extensive lichenological studies in lime-hornbeam forests in the Masurian Lakeland, N Poland (Fig. 1).Further localities of the species were recorded in two forest reserves in Central Poland.The species seems to be relatively frequent in northern and Central Poland, especially in well preserved lime-hornbeam forests, and may also be frequent in other parts of Poland.R. degeliana may be overlooked or not distinguished because of its fine, inconspicuous sterile thalli.
The aim of this study is to describe R. degeliana and to indicate the most important diagnostic characters helpful in its identification during field studies and in the analysis of the herbarium material.

MATERIAL AND METHODS
The material was collected between 2006 and 2009.Morphological and biochemical characters of the specimens collected were examined using standard lichenological assessment analyses.Thin layer chromatography in solvent C was used in chemical analyses to differentiate secondary metabolites (Orange et al. 2001).The nomenclature of lichens follows Fałtynowicz (2003), Blanco et al. (2004) and Kauff & Büdel (2005).The material is deposited in the Herbarium of the Department of Mycology, Warmia and Mazury Univeristy, Olsztyn (OLTC-L), and in the Herbarium of the University of Łódź (LOD-L).Coppins -Lichenologist 15 (2): 147 (1983).
eCology.R. degeliana has been recorded almost exclusively on the bark of deciduous trees of the genera Acer, Betula, Carpinus, Corylus, Quercus, Sorbus, Tilia, mostly on Alnus and Salix in northern Europe (Tønsberg 1992;Mayrhofer, Moberg 2002).It has exceptionally been recorded on the bark of coniferous shrubs (Juniperus).This paper presents the first record of the species on wood.R. degeliana has been recorded both in open areas and in mixed or deciduous forests, often in shady and humid sites, e.g. in river valleys.
In Poland, the lichen has been recorded in old deciduous forests (lime-hornbeam forest, heliophilous oak forest) in places usually moderately humid and shaded, exceptionally on the bark of trees growing along roads within or on the edges of forests.
World distribution.Rinodina degeliana is a relatively rare lichen, widespread in the Northern Hemisphere.Outside Europe, the species is known from north-eastern (NE USA, SE Canada) and north-western North America (McCune 2006;Esslinger 2007), and central-eastern Asia (Hauck, Javkhlan 2006;Hauck et al. 2007).
disCussion.Rinodina degeliana produces diminutive, inconspicuous thalli that are difficult to distinguish among other crustose sorediate lichens in the field.A considerable part of the specimens reported here was collected by the author accidentally together with other lichens.The species can relatively easily be distinguished in the laboratory.It is characterised by, for instance, crustose to subsquamulose areoles of the thallus, marginal, mostly labriform soralia and atranorin and zeorin content (Tab.1).The chemistry of only one sorediate lichen, Rinodina griseosoralifera Coppins, is identical to that of R. degeliana.However, R. griseosoralifera differs by a lower concentration of atranorin, which results in the absence of a strong reaction with K and a usually weak reaction with PD (Coppins 1989;Czarnota, Kukwa 2007).R. griseosoralifera is additionally differentiated by flat to ± convex, oval areoles of the thallus and blue-grey superficial soralia.R. degeliana is often accompanied by R. efflorescens in the Polish material.The latter sorediate species sometimes produces soralia on the margins of small areoles; however, it never forms soralia on their underside (labriform soralia).R. efflorescens is additionally distinguished by its chemistry.It contains pannarin (and additional substances) which causes a colour PD reaction (PD+ orange-red) of the soralia, usually green-or brown-pigmented.Because of a similar yellow PD reaction of the soralia, R. degeliana may be mistaken with Buellia griseovirens (Turner et Borrer ex Sm.) Almb.B. griseovirens, however, differs by its chemistry (norstictic acid, stictic acid compound), usually a more or less continuous thallus and roundish, surface soralia, often grey-or bluish tinged.Some strongly sorediate specimens of R. degeliana may resemble powdery thalli of lichens belonging to the genus Lepraria Ach.R. degeliana differs from them by a colour reaction with PD: a distinctly yellow reaction with PD is not obtained for any of the representatives of the genus Lepraria with granular soredia (only L. elobata has a PD+ orange reaction).

Table 1
Distinguishing features between Rinodina degeliana and superficially similar species (acc.to various sources)