New and noteworthy species of lichens from the Augustów Forest (northeastern Poland)

The Augustów Forest is one of the biggest forest complex in Poland. In this paper, 13 rare species of lichens from Augustów Forest are presented. Four of these species are new to Augustów Forest: Bacidina egenula, Lecanora persimilis, Rhizocarpon reductum, Scoliciosporum pruinosum and one species, Rhizocarpon hochstetteri, is new to northeastern Poland. Short notes on their features and distributions are provided.


Introduction
One of the largest forest complexes in Poland is the Augustów Forest, situated in northeastern part of the country, in the Podlaskie Province (Fig. 1). Along with the part of Forest in Lithuania and Belarus, which are its immediate neighbors, the Augustów Forest covers the area over 1600 km 2 and thus constitutes one of the largest dense forest complex in Europe. The Polish part of the Augustów Forest covers around 1100 km 2 . In 1989, the northern part of the Augustów Forest has been appointed Wigry National Park [1].
In terms of weather condition, the Augustów Forest is characterized by distinct features of the continental climate. The main stand types of the Augustów Forest are: fresh coniferous forest, the fresh mixed coniferous forest, and fresh mixed forest, which occupy 39.3%, 27.2%, and 10.3%, respectively, of the area of Augustów Forest. The main forest-forming species in the Augustów Forest is Sots pine (Pinus sylvestris) [1,2].
The Augustów Forest is characterized by a high diversity of lichen species. Currently, in Augustów Forest (including the Wigry National Park) there are 365 known lichens taxa [1][2][3].
The aim of this study was to provide further data on rare and otherwise noteworthy lichen species from the Augustów Forest.

Material and methods
The specimens for this study were collected during field survey in the Augustów Forest in 2015 and 2016.

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Morphological characters (thickness, structure, and color of thallus and prothallus, color, shape, and size of soralia and apothecia) were examined using stereomicroscope Leica EZ4. Examination of anatomical features, i.e., thickness and color of hypothecium, hymenium, excipulum proprium, number of spores in asci, size and shape of ascospores were done with light microscope Leica DM500.
The chemical analyses were carried out using thin layer chromatography (TLC) according to Orange et al. [21]. The lichen species nomenclature follows Fałtynowicz and Kossowska [22].
All recorded sites are located in the ATPOL grid square system [2]. The geographical coordinates of study sites of the Augustów Forest were recorded by GPS using the WGS84 datum.
The collected specimens are deposited in the Herbarium of Institute of Biology, University of Bialystok for future reference.

Bacidina egenula (Nyl.) Vĕzda
New to the Augustów Forest. The species was reported for the first time from Polish lowland from the Białowieża Forest [19]. So far, the species has been reported only from the southern part of the country (see Fałtynowicz [24]). Bacidia egenula is a species often recorded on anthropogenic (concrete) and siliceous substrates (pebbles, stones). So far, it has been recorded from the Augustów Forest, only from Starożyn Nature Reserve [3]. The species is widespread in temperate to boreal regions of the Holarctic, including Africa, Asia, Europe, and North America. It commonly grows on the smooth bark of trees, on which the thallus forms roundish patches [2]. The species is new to the Augustów Forest. It has been overlooked for a long time in Poland, and was only recently rediscovered after ca. 40 years [19,[24][25][26][27]. Lecanora persimilis is perhaps a boreal to mainly temperate element [27]. It grows on twigs and small branches of neutral-barked deciduous shrubs and trees, especially ash Fraxinus, oak Quercus [2]. The taxon is endangered in Poland, in data deficient category (DD) [28]. The second record in the Augustów Forest [6]. The species is one of few lichens in Poland in which mycobiont is Basidiomycota. So far, it has been recorded from northeastern Poland from several localities [6]. The species occurs on old, decaying logs and on moss-covered soil [2]. Lichenomphalia umbellifera is a near threatened species (NT) in Poland [28]. In the Augustów Forest, this lichen was reported from several localities [2,3,7,10,29], including Wigry National Park [1,[30][31][32]. The species was reported first time in Kozi Rynek Reserve. Lobaria pulmonaria is widely used as an indicator species of undisturbed old-growth forests [2]. It is an endangered species (EN) in Poland [28]. So far, it has been recorded from the Augustów Forest only from Starożyn Nature Reserve [3]. Melanohalea olivacea is perhaps a circumboreal-montane species, most often found on the barks of Betula [3]. Melanohalea olivacea is a critically endangered species (CR) in Poland [28]. So far, this species has been reported from only few localities [2,3,29]. In the Kozi Rynek Nature Reserve, it was reported only by Cieśliński and Tobolewski [29] and Cieśliński [2]. Menegazzia terebrata is an indicator species for old and biologically rich forests in Poland [2]. The species occurs in damp shady woods on barks of trees such as Alnus, Betula, Fraxinus, Quercus. Menegazzia terebrata is a critically endangered species (CR) in Poland [28]. This species is characterized by crustose thallus, thin, areolate, concentrated, grey to brown (Fig. 2). Areoles -0.8 mm in diameter. Prothallus black. Apothecia up to 1.3 mm in diameter, insignificantly outstanding over thallus, black, matt. Disc nude, flat to easily convex, smooth. Margin enough thick or thin, persistent or dying out. Epihymenium brown. Hymenium 100-110 µm high, hyaline. Hypothecium dark brown (Fig. 3).

Rhizocarpon reductum Th. Fr.
New to the Augustów Forest. This saxicolous lichen is quite common in Poland [35]. The species grows on stones and pebbles.
The distinction of R. reductum is related to the changes in the taxonomy of Rhizocarpon obscuratum (Ach.) Massal. complex, with hyaline and muriform ascospores [35][36][37]. Examination of the specimens upon which R. obscuratum is based revealed that they are mostly referable to the species currently known as R. lavatum. According to Fryday [36], R. reductum is resurrected for specimens with small ascospores and a thallus containing stictic acid formerly placed there, whereas specimens with larger ascospores and a thallus lacking lichen substances are more referred to R. lavatum [35,37].

Scoliciosporum pruinosum (P. James) Vĕzda
New to the Augustów Forest. In Poland, it was reported only from few localities, in old deciduous forests (see Fałtynowicz [24]). It is a mild-temperature species, grown on barks of deciduous trees. Scoliciosporum pruinosum is an endangered in Poland, in data deficient category (DD) [28].
In the Augustów Forest, it was reported from only few localities -Starożyn, Perkuć, Kozi Rynek nature reserves [2,3,6,29]. This is an indicator species for old and biologically rich forests in Poland [2]. It commonly grows on sheltered, smooth-barked, deciduous trees. Thelotrema lepadinum is an endangered species (EN) in Poland [28]. In conclusion, four species of lichens, namely Bacidina egenula, Lecanora persimilis, Rhizocarpon reductum, Scoliciosporum pruinosum, presented in this paper are new species for the Augustów Forest, whereas Rhizocarpon hochstetteri is new to northeastern Poland.