For the first time in Europe , an East Asian rust fungus

In Vyzhnytsia National Nature Park (Chernivtsi Region, Ukraine), an invasive rust fungus Melampsoridium hiratsukanum was recorded on the new for Ukraine host plants, Alnus glutinosa and Alnus × pubescens, the natural hybrid of A. incana and A. glutinosa. In Europe M. hiratsukanum is currently known from Austria, Czech Republic, Denmark, Estonia, Finland, Hungary, Germany, Italy, Latvia, Lithuania, Norway, Poland, Romania, Russia, Slovakia, Sweden, Switzerland, Turkey, UK, and Ukraine. At present, the distribution of M. hiratsukanum in Ukraine is confined to the Ukrainian Carpathians; however, it could not be excluded that in future it may spread into the lowland part of the country. A list of all localities in which M. hiratsukanum was recorded in Ukraine is presented. The article is illustrated by micrographs obtained by scanning electron microscopy.

The aims of this publication are to inform about records of M. hiratsukanum on the new for Ukraine host plants and collate the information on currently known localities of this fungus in Ukraine.

Matherials and methods
Specimens collected in the field were labelled and dried for further treatment.Urediniospores mounted in water and/or lactic acid were investigated by light microscopy under Primo Star microscope and AxioVision 4.7 software, used as well for measurements of microstructures.For scanning electron microscopy samples were coated with an ultrathin coating of gold by ion beam sputtering unit JFC-1100.Images were obtained by scanning electron microscope JEOL JSM-6060 LA.
The specimens are deposited in Mycological Herbarium of M.G.Kholodny Institute of Botany, National Academy of Sciences of Ukraine (KW).

Results and discussion
According to literature data, M. hiratsukanum was observed in Scotland and Ireland as early as the beginning of the 20 th century (Wilson, Henderson, 1966), but from later publications (Roll-Hansen, Roll-Hansen, 1981;Henderson, Bennell, 1979) it was shown that the parasite of birch, M. betulinum (Pers.)Kleb., can also infect alder and that all previously known European records of the rust on Alnus Mill.belong to this species.Studies using molecular phylogenetic methods (Hantula et al., 2009) confirmed that M. hiratsukanum appeared in Europe in the mid-1990s, while in the UK (Scotland) on Alnus glutinosa (L.) Gaertn.occurs endemic rust indistinguishable from M. betulinum.It should be noted that several records of M. betulinum on A. glutinosa were also reported for Belgium (Vanderweyen, 2010).The rust of alder is also known from New Zealand, but as it was shown by molecular phylogenetic analysis, the pathogen there is M. betulinum, not M. hiratsukanum (McKenzie et al., 2013).
Most records of M. hiratsukanum in Europe are reported on A. incana.On A. glutinosa this fungus occurs much less frequently; moreover, in many cases it was recorded on seedlings (Piątek et al., 2001), in forest nursery (Szabo, 2002), or in close proximity to infected plants of A. incana (Müller, 2003Markovskaja, 2013).In Germany it was collected on Duschekia alnobetula (Ehrh.)Pouzar (syn. A. viridis (Chaix) DC.) (Kruse, 2014), in Turkey -on A. orientalis Decne.(Sert, Sumbul, 2005).There are two records of M. hiratsukanum on Betula pubescens Ehrh. in the UK, confirmed by molecular methods (Lane et al., 2013).In Ukraine, M. hiratsukanum was first reported from Gorgany Nature Reserve on A. incana in the end of August 2010 (Tykhonenko, 2011).In subsequent years on the same host plant more samples were collected in other parts of the Ukrainian Carpathians (see a list at the end of the article).During mycological surveys in Vyzhnytsia National Nature Park (Chernivtsi Region) on 23-24 August 2015, the development of this fungus was noted on A. glutinosa and Alnus × pubescens Tausch (a natural hybrid of A. incana and A. glutinosa).On both of these species, the rust was observed in the immediate proximity to heavily infected plants of A. incana.The morphological features of the fungus on A. glutinosa and Alnus × pubescens are consistent with the diagnosis of M. hiratsukanum and distinct from the close species, M. betulinum.In particular, the entire surface of its urediniospores is covered with more or less uniform spines, while in M. betulinum the spines gradually decrease in size from the base to the upper part of spore so that its top is a free of spines smooth area (Figure , b,  d, f At present, the distribution of M. hiratsukanum in Ukraine is confined to the Ukrainian Carpathians; however, it could not be excluded that in future the fungus may spread into the lowland part of the country.This rust causing premature defoliation, which certainly affects the physiological state of plants, is of significant environmental importance in riparian habitats.
A list of currently known localities of Melampsoridium hiratsukanum S. Ito ex Hirats.f. in Ukraine.

Chernivtsi Region
).Furthermore, ostiolar cells of uredinium are much longer (up to 40 µm on A. glutinosa and up to 46 µm on Alnus × pubescens) than those of M. betulinum (up to 20 µm) (Figure, a, c, e).Urediniospores size in our specimens of M. hiratsukanum (18.2-25.1 × 8.8-10,6 µm on A. glutinosa and 19.0-26.4× 9.2-13.1 µm on Alnus × pubescens) are slightly smaller than those of M. betulinum on Betula pubescens Ehrh.(20.6-29.0× 9.0-12.0µm) in a specimen collected in the same region of the Ukrainian Carpathians.According to our observations ostiolar cells obviously play an important role in the release of urediniospores: in response to humidity changes, they bend and unbend to close and open the mouth of uredinium.