The Lichens and Lichenicolous Fungi of Belgium and Luxembourg ...

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THE LICHENS OF BELGIUM AND LUXEMBOURG. AN ANNOTATED CHECKLIST 7
Introduction
ichenology in Belgium and Luxembourg started in the early XIXth century, but it was
especially towards the end of that century that national floras and checklists became
available. In 1898, De Wildeman published a checklist of the Belgian lichens, with
indications on localities and references for each species. One year before, Koltz (1897) did the
same for Luxembourg. In 1938, Duvigneaud & Giltay presented a revised Belgian checklist,
but this time without chorological data. The number of species recognized by these authors
was rather low, with 586 species reported from Belgium, and only 404 from Luxembourg.
After 1900, the lichenological exploration dramatically declined in these two countries,
and it is only since the beginning of the sixties that, through the work of Prof. Jacques
Lambinon, a new era of lichenology started. It is also during that time that Belgian
lichenologists started exploring the neighbouring areas of northern France, which are
therefore included within the scope of the present checklist.
Since the early eighties, we have attempted to fill the gap by preparing a detailed inventory
of crustose lichens, as well as of lichenicolous fungi which, although not lichenized,
have traditionally been studied by lichenologists. The rapid development in lichen
taxonomy, the new techniques to study them (e. g. by thin layer chromatography), the
availability of modern illustrated floras, the continuous discovery of previously unknown
taxa in Europe, and also the meticulous search in the field for minuscule, inconspicuous
crusts in previously neglected habitats rapidly led us to discover or recognize over 700
additional species, which had never been recorded in Belgium or Luxembourg before.
The precious help of several colleagues and friends, mainly from the Benelux countries,
was invaluable to achieve these results.
Nowadays, the total number of accepted species reaches 1151, more than twice the
number of previously published taxa. Nevertheless, no doubt this number will continue
to increase in the forthcoming years for several reasons: we know of many, often sterile
crusts, that still require identification; several genera are poorly known in the area of
study (e. g. Acarospora, Thelidium, Verrucaria); many lichenicolous fungi and some
small, inconspicuous crustose lichens are only found by chance, and despite very careful
sampling during these past years, many have certainly been missed; comparison with
modern European floras or checklists suggests that a relatively large number of
additional species might occur in the study area.
Therefore the aim of the present checklist is to update our current knowledge of lichens
and lichenicolous fungi in Belgium, Luxembourg and northern France, and to encourage
students and botanists to pay attention to this fascinating world of organisms. Even if
the exploration of our lichen flora might be considered as finished, students should not
forget that many species are still very poorly recorded, and that much additional work,
like the preparation of a distribution atlas or even the production of a modern flora, with
complete identification keys, still have to be realized. Furthermore, we should not forget
that lichens, which are excellent indicators of biodiversity, are vanishing rapidly, and
that their conservation should be treated with priority.