THREE SPECIES OF HETERODERMIA RECORDED IN MONGOLIA

Heterodermia hypoleuca (Ach.) Treis.,H. japonica (M. Sato) Swinscow & Krogand H. subascendens (Asahina) Trass. have been recorded for the first time in Mongolia. Data on substrates, habitats, distribution are listed for every species. Taxonomic comments and distinctive characters are provided for these species. The habitats are briefly described and the frequently associated species are listed. It is interesting to note that as a result of processing hundreds of herbarium collections of lichens, numerous new species were found in Mongolia. This means that there is still a substantial gap in the knowledge, especially about the lichen flora of remote corners of the country, which are numerous.


INTRODUCTION
Recently, as mentioned in the work of M. Hauck et all [11] the lichen flora of Mongolia is better known as compared to many other Central Asian countries or regions (Central Asia is treated here in a broad sense), like Kazakhstan [32], Kyrgyzstan [22], Tajikistan [19], Xinjiang [1] or Tibet [33]. According to the checklist of the mongolian lichens by Biazrov Lev G [5] there are 1067 lichens and 13 lichenicolous fungi now known in Mongolia. The small number of lichenicolous fungi registered so far is perhaps because of the limited investigation carried out into this group of fungi in Mongolia [14,15,16,17]. This time, we present 3 species to be added to the lichen flora of Mongolia. Until recently only two species of Heterodermia such as H. leucomelos (L.) Poelt from willow bark [2] and H. speciosa (Wulfen in Jacq.) Trevis from mossy rock [9,10,7,8,11] were known from a very few localities in Mongolia.
One of the main reasons for the poor knowledge of lichenised fungi and their ecology has been the lack of adequate Information about the taxomony of Physciaceae, Heterodermia species. In some cases, even frequent species had not been identified until recently. We hope that many unknown species are included in the herbarium material (UBA) of the Mongolian Academy of Sciences.
-58 - The objective of the present work is to present a new species of Heterodermia of lichenised Ascomycetes and Physciaceae, newly discovered in Mongolia for the first time. Species identification of Heterodermia and Physciaceae were carried out basing on samples of lichens collected by the author in 1995 from Bogd Uul Mountain in the southern outskirts of Ulaanbaatar.

PMAS
The Bogd Uul mountain is located on the banks of the Tuul River that runs through the city. Another place from where Heterodermia hypoleuca (Ach.) Treis was collected in 2013 comes from the Great Khingan floristic districts in the eastern part of Mongolia.

RESULTS AND DISCUSSION
Upper surface: greyish white or greenish grey, epruinose, sorediate on the undersides of lobe apices.
Apothecia: margin sorediate, not seen in Mongolian material but reported to be very rare (Kurokawa, 1962) Kurokawa (1962) published a definitive world monograph of the genus Anaptychia in which 72 predominately tropical species were treated. Subsequently, that genus was recognized as heterogeneous by Poelt (1965), who separated the genus Heterodermia with smooth, thick-walled spores and the constant occurrence of atranorin in the upper cortex from Anaptychia, all species of which have Physconia-type spores and lake atranorin in the upper cortex. That's way some of Kurokawa's originally recognised species have been transferred to Heterodermia. This delimitation is now widely accepted and also by Kurokawa (1998).
As well as, Heterodermia is most similar to Physcia in size and colour. It differs mainly in the structure of the upper cortex (pseudoparenchyma in Physcia), and spore type (primarily Physcia-type spores in Physcia). The structure of the upper cortex in Heterodermia gives the surface the appearance of flowing toward the lobe tips, whereas the upper surface in Physcia has a uniform, unoriented appearance [6].
Heterodermia hypoleuca is characterised by the sorediate upper surface, ±radiating lobe apices, the absence of a lower cortex, white to blackish violet lower surface, ascospores with sporoblastidia and the presence of atranorin and triterpenes. This fringe lichen is much like H. speciosa but without soredia. Also Heterodermia rugulosa is a southwestern species similar to H. hypoleuca, but its upper surface can be quite pruinose, and its lower surface is smooth and with cortex.
Heterodermia japonica is characterised by the sorediate upper surface, ± radiating lobe apices, the absence of a lower cortex, white to blackish violet lower surface, ascospores with sporoblastidia and the presence of atranorin and triterpenes.
Heterodermia subascendens is characterised by the ascending or suberect  lobes with marginal, sublabriform soralia and spathuliform apices, white, ecorticate lower surface with yellow spots (K+ purple), ascospores with sporoblastidia, and the presence of atranoin, zeorin and skyrin [34]. Interestingly, the Bogd Uul Mountain, where H. japonica and H.subascendens were registered, is one of the fragmented regions of permafrost replete with river granite stone, which is one of the main elements of the relief formation of the are. Although the lichen biota of the protected Bogd Uul Mountain has been studied quite well, one of its most unique characteristics are the species widespread in the boreal mountain area [8]. The lichen biota in the forests of Larix sibirica, Pinus selvestris, Piceao bovata and Betula plantyphylla of this protected mountain are similar to almost all the species occurring also in other northern Mongolian mountainsous especially Khentii Mountain region in northeast Mongolia.
Heterodermia hypoleuca is characteristic to the eastern part of Mongolia. It is widespread in the eastern part Russia, China, Korea, Japan North and South America, East and South Africa and Australia [18]. At the present stage of geological history, when higher vascular plants cannot point to the ancient relations between the flora of far-away regions, lichens convincingly demonstrate that such connections and relationship do exist. Moreover, it is possible to assume with a high degree of certainty that some species of Heterodermia are also found in North-Eastern Mongolia and North-East China, which border with Southeast Transbaikalia. Similar ranges of these species of Heterodermia indicate ancient floristic connections between Baikal Siberia and the Mediterranean, which were connected by the common space of the formation of the arid desert-steppe Eurasian-North-African flora [31].

CONCLUSIONS
A study on taxonomy of some species of Heterodermia in Mongolia is presented. Phenotypic analysis was based on morphological, anatomical, and chemical characters. The results suggest that the genus Heterodermia is monophyletic. Some characters (e.g. corticate vs. ecorticate lower surface, absence vs. presence of yellow pigments or soredia) are shown to be taxonomically significant within the genus.
Of the five species of Heterodermia known to occur in Mongolia, three were confirmed in this study.