Leccinum variicolor ( Basidiomycota , Boletales ) in Poland

The genus Leccinum Gray of the family Boletaceae Chevall. and the order Boletales E.-J. Gilbert is represented by ca. 75 species (Kirk et al. 2008). Fourteen of them are known from Poland (Wojewoda 2003; Łuszczyński 2008). Almost all species of this ectomycorrhizal genus are generally highly host-tree specific (Den Bakker et al. 2004). Leccinum variicolor is widespread, but not common in Europe, and occurs in the northern hemisphere, in the temperate, boreal, subalpine and arctic zones (e.g. Den Bakker, Noordeloos 2005; Knudsen, Taylor 2012; Noordeloos (online)). It is a rare species in Poland although it is known from various regions in the country, e.g. from the Lublin region (Flisińska 2004), the Wielkopolska region (Ślusarczyk 2007) and the Góry Świętokrzyskie Mts (Łuszczyński 2007, 2008). Leccinum variicolor is included on the red list of macrofungi in Upper Silesia (Wojewoda 1999) and red list of Basidiomycetes in the Góry Świętokrzyskie Mts (Łuszczyński 2002, 2008). This paper describes the morphology and ecology of Leccinum variicolor as well as its distribution in Poland.


INTRODUCTION
The genus Leccinum Gray of the family Boletaceae Chevall.and the order Boletales E.-J.Gilbert is represented by ca.75 species (Kirk et al. 2008).Fourteen of them are known from Poland (Wojewoda 2003;Łuszczyński 2008).Almost all species of this ectomycorrhizal genus are generally highly host-tree specific (Den Bakker et al. 2004).Leccinum variicolor is widespread, but not common in Europe, and occurs in the northern hemisphere, in the temperate, boreal, subalpine and arctic zones (e.g.Den Bakker, Noordeloos 2005;Knudsen, Taylor 2012;Noordeloos (online)).It is a rare species in Poland although it is known from various regions in the country, e.g. from the Lublin region (Flisińska 2004), the Wielkopolska region (Ślusarczyk 2007) and the Góry Świętokrzyskie Mts (Łuszczyński 2007, 2008).Leccinum variicolor is included on the red list of macrofungi in Upper Silesia (Wojewoda 1999) and red list of Basidiomycetes in the Góry Świętokrzyskie Mts (Łuszczyński 2002, 2008).This paper describes the morphology and ecology of Leccinum variicolor as well as its distribution in Poland.

MATERIAL AND METHODS
The description of the basidiocarp morphology and habitats is based on original specimens and their localities, supplemented by information from the literature.

© The Author(s) 2014 Published by Polish Botanical Society
Microscopic features were measured by standard light microscopy (LM).Basidia and spore measurements in the descriptions of the species are based on 30 measurements per specimen from 18 collections.Dimensions of the basidia and the spores are given as follows: (minimum value-) 1 st decile -9 th decile (-maximum value).Spore length to width ratios are reported as Q.Micrographs were taken with a scanning electron microscope Zeiss EVO LS10 (SEM) in the Centre for Molecular Biology and Biotechnology, Environmental Testing Laboratory University of Szczecin (Poland).The cartogram map (Fig. 1) is based on our investigations and all available published data and unpublished (e.g.herbarium) records.The distribution was mapped using the grid square system following the "Atlas of the Geographical Distribution of Fungi in Poland" (Wojewoda 2000).Geographical regions are given after Kondracki (2002).The nomenclature of vascular plants follows Mirek et al. (2002) and that of plant communities follows Matuszkiewicz (2001).The specimens were collected by the authors in Pomerania during 1998-2011 and were deposited in the Herbarium of the Department of Botany and Nature Conservation, Szczecin University (SZUB), Poland.Watling, Notes R. bot. Gdn Edinb. 24: 268 (1969) -Boletaceae, Boletales, Agaricomycetidae, Agaricomycetes, Agaricomycotina, Basidiomycota, Fungi (Kirk et al. 2008).Pileus 30-120 mm in diameter, convex to plano-convex, with entire margin, dark brown to blackish brown, greyish brown or mouse grey, usually with lighter ochraceous or yellowish grey spots, tomentous; tubes ventricose, 7-18 mm long, white when young, later grey or cream, vinaceous to brown when bruised; pores ca.0.5 mm in diameter, white or cream, ochraceous when bruised; stipe 70-180 x 10-35 mm, solid, cylindrical to clavate, white, with small grey to blackish brown squamules, often discolouring greenish blue at base; context white, gradually or quickly staining pink to coral red in pileus and apex of upper half of stipe, often intensely green blue in the lower half of stipe after 1-5 hours (Fig. 2); spores (10) 13.5-17.5(20.0) x 5.0-6.5 (7.0) µm, Q = 2.4-3.1, smooth, fusiform with or without a suprahilar depression (Fig. 3a, b); basidia 23.0-32.0(34.2) x 8.5-11.0(13.0) µm, mostly with 4 sterigmata.
LocaLities in PoLand.Specimens indicated by asterisk (*) have not been examined by the authors.

DISCUSSION AND CONCLUSIONS
In Europe, Leccinum variicolor is regarded as a rare species, more frequent only in Northern Europe (Knudsen, Taylor 2012;Noordeloos, online).It usually occurs in different forest communities, in tree stands where birch, which is its mycorrhizal partner, is either a dominant species or an admixture (Den Bakker et al. 2004Bakker et al. , 2007;;Legon et al. 2009).This would indicate that the species should be considerably more frequent.Sometimes considerable morphological similarity is observed between Leccinum variicolor and Leccinum scabrum, and these two species may not be distinguished in the field.They are distinguished by the flesh at the stem base which turns blue-green in L. variicolor but the colouration may be visible after a few hours.Both taxa also differ by habitat requirements.L. scabrum mainly grows in dry places (e.g.Wojewoda 2003) while L. variicolor occurs in moist sites, wetlands and peatlands (Chinan 2011;Stasińska 2011;Knudsen, Taylor 2012).
Although it is widespread, Leccinum variicolor is a rare and protected species in many European countries (e.g.Siller et al. 2005) or it is red-listed, e.g., in Romania (Tănase, Pob 2005; treated as vulnerable VU), in the Czech Republic (Holec, Beran 2006; treated as near threatened NT) and in Hungary (Siller, Vasas 1995; treated as endangered, vulnerable and rare -category 2).In Poland, the species is included on regional red lists of fungi only in Upper Silesia (category I -indeterminate, Wojewoda 1999) and the Góry Świętokrzyskie Mts (category R -rare, Łuszczyński 2002; category NT -near threatened, Łuszczyński 2008).It may be recommended to include the species on the national red list of macrofungi (Wojewoda, Ławrynowicz 2006) as nearly half of all its records in Poland to date are from peatlands and its margins (cf. the list of localities).According to Krieglsteiner (2000), wetland draining, occurring worldwide for many years, is a threat to L. variicolor.
The distribution of L. variicolor in Poland is not recognized well and the number of its sites may be greater than it is believed.Based on the available published and unpublished data and our observations, the species is probably rare and threatened in Poland.