Occurrence of black truffles in Poland

Tuber aestivum Vittad., T. mesentericum Vittad. and T. bellonae Quél. have been distinguished in recent collections of hypogeous fungi in Poland. Up till now only T. mesentericum has herbarial documentation. T. aestivum was confirmed to occur in Poland. Seven localities are documented with exiccates, but it is considered as a complex species. Some specimens have features of T. uncinatum Chat. not distinctively separated from these of T. aestivumVittad., therefore are treated as its form. The studies based on rich material support the concept of Tuber bellonae as a separate species close to T. mesentericum.


INTRODUCTION
Hypogeous fungi and especially truffles have been of increasing interest in Poland in the recent years. The old data on the occurrence of truffles in Poland were set together by Lubelska (1953). She mentions 8 species of truffles, among them Tuber aestivum from 6 localities on the base of papers by: Caspary (1886), Błoński (1888), and Alexandrowicz & Błoński (1894). It was the only black truffle indicated; this taxon overlapped also T. mesentericum, but no herbarium material is now available to analyse this question.
After about hundred years T. mesentericum was discovered on Częstochowa Upland in two localities (Ławrynowicz 1988, 1990, 1999) in course of systematical searching of hypogeous fungi.
These fungi produce fruit bodies only in some places called hypogeous oasas or nests, where ecological conditions are suitable. Similarly, only in some years the climatic conditions unable formation of fruit bodies. The year 2007 was exceptional. The authors of this paper found independently black truffles in 13 sites. The analysis of the material permits to identify 4 taxons: Tuber aestivum, T. aestivum forma uncinatum, T. mesentericum, and T. bellonae; the latter as a new species for Poland.

MATERIAL AND METHODS
The investigations were taken out at the calcareous hilly area, not exceeding 300 m a.s.l. On the base of type of ecosystem, density of vegetation cover, type of soil and features known as characteristic for truffle sites, the environment places for excavations were chosen. Numerous collections of different hypogeous species were made during several years of field searching, but in 2007, starting from the early summer, the fruit bodies of black truffles were to be found. Also in course of monitoring two above mentioned sites of Tuber mesentericum two new localities of T. aestivum were discovered in July 2007.
Altogether more than two hundred of fruit bodies were observed by two of us (TK and MF). In some cases a dog was helping to detect the ripe carpophores. Specimens were described immediately after taking out from the soil and in most cases documented at the sites concerned.
Fruit bodies were analysed taxonomically using the traditional procedure. The micromorphological and anatomical features of peridium cells, asci and ascospores were examined under Eclypse 600 E-microscope (Nikon) (200x, 400x, 1000x). Materials were identified according to Montecchi and Sarasini (2000), Riousset et al. (2001) and some other authors indicated in the "References". The localities are indicated on three maps in the ATPOL system.
RemaRks. T. aestivum is a heterogenous species. Montecchi and Sarasini (2000) mention the results of studies indicating 18 various clones or breeds of this species but none of them reached the species level. The Polish collections of T. aestivum present great variability, as well. The study has just started. The collections from three localities contain fruit bodies of slightly different character, what allow considering them to be close to Tuber uncinatum Chat. according to Riousset et al. (2001).
ecology. The fruit bodies were found in association with Fagus sylvatica, Quercus robur, Q. petraea and variety of other deciduous trees on calcareous soil. The collections come from three uplands, mostly from the lower parts of the hills. The species was found in places of heavy human impact at the forest paths and tourist trails, in Fig. 1 the vicinity of houses or in the area facing a new arrangement of roads. It means that the occurrence of T. aestivum is seriously endangered (Pl. I 1, 3).
DistRibution. T. aestivum is considered to be the most widespread species among edible truffles in Europe, occurring from Mediterranean zone to South Scandinavia (Veden et al. 2001). Lubelska (1954) gives six localities of the species in Poland mainly on the basis of popular literature. Recent collections of T. aestivum are indicated in the Figure 1.
localities Fruit bodies similar to those of T. aestivum Vittad. The differences are in smaller warts on the surface, darker colour of gleba, more intensive odour, spores ornamented with more distinct reticulum with meshes up to 4 μm high, curved in the upper part. The last feature was observed only in some spores. On the basis of three collections we concluded that T. aestivum forma uncinatum is a late autumn form of T. aestivum adapted to more humid sites (Pl. I 2, 4, 5, 6).
RemaRks. Recent collections of T. aestivum present a great taxonomical variability of this species. The most distinctly separated group is that showing the features of T. aestivum forma uncinatum. Continuation of collecting and taxonomical studies may bring additional arguments to verify our point of view in this question.
ecology. In humus-clay soil in calcareous area. Under Carpinus betulus, Acer pseudoplatanus, Quercus petrea, Corylus avellana and other trees. On hills up to 290 m a.s.l., but usually in the lower parts; autumn and winter mounts; in great quantities: more than a hundred of carpophores were collected in three localities.
DistRibution. The localities are indicated in Figure 1. The occurrence is endangered because of forest management practices and penetration by people from adjacent villages. The whole area should be protected.
T. mesentericum was distinguished from T. aestivum by having smaller fruit bodies, ornamented with smaller warts, obtuse or depressed at the apex, black colour of surface with black-blue reflex becoming black gray when dried, having cavity at the base or on side of carpophores. The spores of T. mesentericum are larger and ornamented with more complete reticulum than these of T. aestivum. Examination of rich materials collected by the authors supports the separation of these two species (Pl. II 2). ecology. In humus-sandy soil, clay mixed with small calcareous stones. Under Fagus sylvatica, Carpinus betulus, Corylus avellana, Quercus robur, Q. petraea. T. mesentericum was found in different sites as T. aestivum. Even when the same locality has been stated for both species, they do not grow together but in different sites separated by distance of at least 50 m.
DistRibution. This is the only species of black truffles monitored in two localities since 1981 and 1997, respectively. Together with recent collections, it is known from five localities indicated in Figure 2. Exact distribution of the species in Europe is difficult to determine because T. mesentericum and T. aestivum had been treated as one taxon for a long time.
ecology. In humus-clay or clay soils mixed with small calcareous stones, usually covered with thin litter layer. Tuber bellonae has been found under Quercus petraea, Corylus avellana and Fagus sylvatica on calcareous soils (Pl. II 1).
DistRibution. As the species has not been distinguished as a separate taxon by many authors for a long time, its real distribution is impossible to determine. The collections comes from three localities in Poland indicated in the Figure 3. localities

GENERAL REMARKS AND CONCLUSIONS
Increasing interest in hypogeous fungi in Poland results in discovering of sev-ing interest in hypogeous fungi in Poland results in discovering of several new localities and gathering big collections of carpophores, among them black truffles. This activity is of a great value for research and practice. The knowledge of occurrence of black truffles in natural habitats and of its distribution could help to better recognize the ecological requirements of particular truffle species.
The results of taxonomical, ecological and chorological analyses are concluded in the identification of four taxa: Tuber bellonae Quél., T. mesentericum Vittad., T. aestivum Vittad., and T. aestivum Vittad. forma uncinatum (Chat.) Montecchi et Borelli. The collected material, consisting of more than 200 fruit bodies, came from 13 localities in calcareous uplands in the South of Poland. Some collections were also signalised by Hilszczańska et al. (2008). In the present paper, Tuber bellonae is reported from Poland for the first time. T. mesentericum has been found and continuously observed since 1981; T. aestivum was mentioned in the literature in 19. century in 6 localities in different parts of Poland (Lubelska 1954). No exsiccates of the latter species coming from these sites were found neither in Polish nor in foreign herbaria, therefore it is impossible to know its exact taxonomical interpretation. The recent collections of fresh carpophores reveal intraspecific variation of Tuber aestivum, enabling us to distinguish a group of uncinatum in the rank of a form. The characteristic features of this taxon are attributed to the collections coming from the most northeastern localities and autumn as well as winter period of occurrence. Through examination of tens of carpophores revealed that part of them do not reach the maturity during the whole vegetation season. On the other hand it comes clear that the production of black truffle carpophores in Poland in the last years increases. Moreover, it seems that fruit bodies of T. mesentericum with cavity and T. bellonae with some depressions in carpophores are better adapted to humid and cold climatic conditions.