Ecology and plectology of Phlebia tremelloidea ( Polyporales , Agaricomycetes )

a rare boreonemoral species, Phlebia tremelloidea (Bres.) Parmasto was characterized morphologically and ecologically basing on Russian material. The specified description of the species was given. the variability of top lamprocystidia, basidia and basidiospores of the fungus was revealed. an abhymenial, medullar, and subhymenial strates of the basidiocarp were characterized. the relationships between developmental environments and morphology of the fungus were discussed.


IntroDUctIon
Phlebia tremelloidea (Bres.)Parmasto [= Ph. lindtneri (Pilát) Parmasto] is rare boreonemoral species known from several localities on eurasian continent.rather variable morphology of this species is a reason of its controversial descriptions as well as rich synonymy, sound for rare taxon.A new finding of this fungus in old boreal forest of arkhangelsk region (european russia) feats us re-examine all accessible material on the species.therefore, the purpose of the present note is generalization of data on taxonomy, morphology and ecology of Ph. tremelloidea.
materIal anD methoDS all accessible material on Ph. tremelloidea, Phlebia lindntneri, Peniophora tremelloidea Bres., and Phlebia merulioidea Parmasto were involved into present investigation.the collections consist of material collected by the authors in some regions of russia as well as selected specimens from the mycological herbarium of the Komarov Botanical Institute (le) (Saint Petersburg).
all specimens were studied and preserved with standard methods.the macroscopic description was based on examination of the fresh material and the analysis of the photos.
the dried material was studied using light microscopic techniques.microscopical study of basidiocarps was carried out as described by gilbertson and ryvarden (1986).Freehand sections and squash mounts of basidiocarps were examined in 5% Koh and 2% cotton Blue.Spore conglomerations were searched in hymenophoral gelatinose matrix.Spore measurements contained 30 spores per specimen.the following abbreviations were used: l -spore length, W -spore width, Q -quotient of the spore length and spore width (l/W ratio).Specimens are preserved in the herbarium of Komarov Botanical Institute (St.Petersburg, le) and Institute of ecological Problems of the north (arkhangelsk, ar).
the position of the species within genus Phlebia is rather stable and widely accepted.only in 2004, it was made new combination Hohenbuehelia lindtneri (Pilát) Spirin (Zmitrovich et al. 2004) on the base of metuloid-like lamprocystidia and a local attachment area of basidiocarp, corresponded with consideration on merulioid fungi as resupinate agarics with disturbed morphogenesis.however, strict phlebioid textura of basidiocarp has forced a re-evaluation of this position for the benefit of recognizing a separate unit of generic rank, Lampromerulius Zmitr.& Spirin ined.(Spirin, Zmitrovich 2009).
the recent molecular study of phlebioid fungi (moreno et al. 2010) based on divergence revealing by ItS and partial 28S rDna sequences not supported an isolated position of 'Lampromerulius': the sequence Ph.lindtneri was clustered with those of 'Steccherinum' lusitanicum (Bres.)ryvarden and Phlebia setulosa (Berk.& m.a.curtis) nakasone in core-Phlebia clade.therefore, the lamprocystidia presence and construction is trailer apomorphy needed in ecomorphological rather than phylogenetical interpretation.
Plectology. the hyphae of Ph. tremelloidea produce mucilaginous substance that leads to cartilaginous context of basidiocarp.Such a feature is connected to reduction of water loss by evaporation and protection the protein bearing hyphae of the deeper regions against microscopic animals, such as mites and spring tails.gelatinized contexts represent a certain water reserve and give important volume to a basidiocarp without engaging much biomass (clémençon 2004).
the basal layer of basidiocarp of Ph. tremelloidea represents an agglutinated hyphal mass forming dense abhymenial plate, i.e. this layer cannot be interpreted as subiculum, rooted into substrate (Fig. 2). the hyphae in this layer are variable in diameter (1.5-4 μm wide) and often bear thickened walls that more precisely can be interpreted as prominent glucane cover.Usually, under 5% Koh these thick-walled hyphae dissolve and stay subinvisible.the hyphal arrangement in this layer is more or less horizontal.near the margin the hyphae form ciliar agglutinated fascicles, furnished by occasional lamprocystidia.
the medullar layer of basidiocarp in Ph. tremelloidea is weakly differentiated from upper and lower strates.this is a huge cartilaginous mass composed by freeleaving strongly gelatinized hyphae.As it seen on figure 2, the hyphal mass of this layer is subinvisible due to mucilaginous substance.the hyphae in this layer have descending orientation.near to subsequent subhymenial strate, some hyphae bear fusiform apical thick-walled swellings.these are precursors of lamprocystidia.In general, hyphal masses of medullar layer form a certain fascicular zones corresponded to hymenophoral ridges.the hyphal ends in these ridges have a tendency to lamprocystidia formations.
the fungus in question is characterized by thickened hymenium (auxohymenium according to clémençon 2004), i.e. candelabriform structure leading to textura porrecta, which is a result of replacement of old basidia by new ones springing from ramifications of the same candelabra growing beyond the general level of the hymenium.In Ph. tremelloidea this layer is enriched and strengthened by mature lamprocystidia.the roots of these strucures are hidden among subhymenial textura porrecta, but in some cases we can mark a total length which reaches 120 μm.However, encrusted part, which consists as a rule 1/3 of total length, is easily observable, and varies in limits 38-60 × 8-18 μm (Tab.1).
the fungal outgrowths appear from underside of fallen logs as roundish patches having an intermerging tendency.the margin generally adhere the substrate, but without rooting into them.Some specimens demonstrate inrolled margin with naked or pruinose (on the manner of Phlebia centrifuga P. Karst.) abhymenial surface.the fact that fully developed basidiocarps can be revealed in august (Parmasto 1962;Zmitrovich et al. 2004; the present data) and keep up to october (Kotiranta, Saarenoksa 2000;Spirin 2002) (and, possibly, later) forces us suppose that the fungus is a slowly growing with potential to survive of winter season.the clearly thickened subhymenium protruded by lamprocystidia supports Parmasto (1962) interpretation of hymenium of the fungus as 'multilayered'.the observations of the fungus during some years are needed to revealing of persisting capacity of this species.conclUSIon Ph. tremelloidea is a slowly-growing phlebioid fungus adapted to colonization of homogeneous (not cavernose) substrata, like decorticated wood or uncracked bark.In contrast to relatives having a transcortical development, like Ph. radiata Fr. or Ph.rufa (Pers.)M.P. Christ., this fungus haven't reserved superficial vegetative mass.therefore, its growth is more slow and even.the numerous lamprocystidia create a rigid skeleton which promotes to constant increasing of hymenial field.The fungus attached to soft conditions of old forests with abundance of fallen logs that allows a long-term (to persisting) sporulation.
of diagnostically important microstructures in Phlebia tremelloidea (fresh material le 269621) abbreviation.thelimiting dimensions marked by boldface.on