Corresponding author: Michael Schmitt (
Academic editor: J. Santiago-Blay
Contribution to the European Symposium on Chrysomelidae, held August 23, 2010, in Budapest, Hungary
A comparison of the geographical distribution patterns of 647 species of
Distribution data of organisms are necessary for basic research, as they provide insights into their potential ecological interactions and the colonisation of a given area. Moreover, comparing distribution patterns, morphological and/or physiological traits can inspire hypotheses on how ecological adaptations and phylogenetic constraints become possible. Such data are also a prerequisite for sound decisions in nature conservation and an integral contribution to applied sciences.
In the autumn of 1987, a group of 18 amateur and professional coleopterists working on leaf beetles decided to co-operate in continuing the faunistics project of Adolf Horion (12.07.1888 – 28.05.1977). He had published a series of 12 volumes on the geographic distribution of beetles in Central Europe between 1941 and 1974 but could not complete his project of treating all coleopteran families. As they considered it necessary to compile the available data on the zoogeography of
We built a database with entries either based on voucher specimens or on reliable literature data. ‘Reliable’ was defined as records with geographic coordinates down to one minute. There is hardly a consensus among zoogeographers how to circumscribe “Central Europe“ in scientific terms.
There are numerous ways to visualise geographic distributions, partly due to the fact that there are several possibilities to project the earth surface on a plane map (see, e.g.
We decided to present our results finally as grid maps with fields of size 30‘ east to west and 20‘ north to south. This provides the opportunity to include records of which we do not have precise geographic data but know definitely to which grid cell they belong. Our rectangle contains 1380 cells in total, 1291 include land, at least partly, and 1126 grid cells lie at least partly over a focus country. The grid cells differ somewhat in size. Their N-S extension is 37.12 km, but the length of their E-W axis and consequently their surface area varies, e.g. between 31.80 km (= 1180.42 km²) at 55°N, 35.77 km (= 1327.78 km²) at 50°N, or 39.21 km (= 1456.59 km²) at 45°N.
The members of the working group chose the larger grid cell size as compared to that used in Great Britain (10 × 10 km,
There are 787 species of
Records were taken into the CHRYFAUN database from (1) the notes of Adolf Horion, forwarded by Dieter Siede, (2) the collections of Zoologisches Forschungsmuseum Alexander Koenig – ZFMK, Bonn (Germany) and Zoologisches Institut und Museum of Ernst-Moritz-Arndt-Universität – EMAU, Greifswald (Germany), and (3) the private collections of Ron Beenen, Manfred Döberl, Uwe Heinig, Horst Kippenberg, “Theo” Michael Schmitt, Matthias Schoeller, Dieter Siede (see above for locations), and Klaus Renner (Bielefeld, Germany). Literature data were taken from the reports published in Fragmenta faunistica 1932-1998 (Adamczewski, Bartoszynski, Bartowska, Bielawski, Brischke, Burakowski, Ciszkiewicz, Enderlein, Glazek, Goljan, Kapuscinski, Karpinski, Karpowicz, Kinel, Krzeminski, Kulczinski, Nunberg, Maczynski, Makolski, Markowski, Mazurowa, Mroczkowski, Ogloblina, Pawlowski, Pisarski, Podoski, Popek, Raabe, Stobiecki, Szymczakowski, Tenenbaum, Wasowska, Wegrzecki, Wierzbicki), Mitteilungen der Arbeitsgemeinschaft rheinischer Koleopterologen (Baumann, Böhme, Brenner, Eisinger, Franzen, Höhner, Junker, Katschak, Koch, Köhler, Matern, Müller, Siede, Stüben, Stumpf, Wagner, Wenzel, Wunderle), Mitteilungen des Entomologischen Vereins Stuttgart (Bense, Braun, Bretzendorfer, Büche, Dynort, Frank, Gladitsch, Hemmann, Kless, Knapp, Konzelmann, Kostenbader, Krell, Lange, Malzacher, Maus, Reibnitz, Rheinheimer, Roppel, Ulbrich, Weber, Wolf-Schwenninger, Ziegler), Geiser (2001),
“Record” means a single collection act for a species, as documented on the label(s) on the pin(s) of the voucher specimen(s), or the equivalent information in a publication. We used only such data which allowed for relating a record to a certain grid cell, and which offered a time specification of “before 1900”, “between 1899 and 1950”, and “after 1949”, or more exact. If there were several specimens on a single pin or a series of several specimens with exactly the same label data, we opened only one “record” and entered the number of specimens in a “remarks” field. The geographical coordinates of the localities were entered exact to the minute when possible. Where we could only assign a locality to a certain grid cell of 20’ × 30’, we used the centre of the grid cell as a dummy in generating distribution maps. In such a record, the assignment of coordinates to the locality was labelled “artificial” in the database.
Our database CHRYFAUN was developed by the first author and was housed at ZFMK until 2009. Since then, the master database is ministered by the first author at EMAU, copies are distributed among the members of the working group. The database software CHRYFAUN is programmed by Hicosoft (Joachim Hilgers, Düsseldorf, Germany) on a MS Visual FoxPro® platform. Distribution maps are produced using DMAP® (by Alan Morton, Penrhynoch, Aberystwyth, Ceredigion, UK).
In the maps produced, grid cells in light yellow indicate those for which we have data. Consequently, we can only speculate on blank areas. As even most common species are not necessarily reported for all covered grid cells, we plot the distribution of the species of interest using red diamonds against the sampled records of all species of the same genus (or a genus with similarly looking species, in case of monotypic genera). The rationale behind this procedure is that collectors would hardly look for a single species and discard specimens of the remaining species of the same genus. Also, we hope to avoid confusing occurrence gaps with report gaps.
Maps were generated for all of the 647 species under study. Of these, 115 were discarded because they were based on less than 10 records. The other maps were compared by eye according to superficial similarity. The maps could be grouped to certain easily circumscribable types, and there were only few intermediates. Afterwards, the types were described as detailed and objective as possible. For this purpose, also the frequency maps of all species were considered. This allowed us to assign each species unequivocally to one of the distribution types.
The 63,136 records for the 647 target species are not distributed equally over the 737 grid cells of which we have data at all.
Frequency distribution map, based on 63,136 records of 647 species over 737 grid cells of 20 × 30 geographic minutes. Blank areas mean no records.
The highest number of records lie in areas (brown squares) where either amateur coleopterists clubs (Rhineland, Baden-Württemberg) or individual collectors (e.g., The Netherlands: Utrecht, Germany: Berlin) are very active, or at touristically and faunistically attractive sites, e. g. Lake Neusiedl in Austria and Hungary.
Species for which we have less than 10 records in the database (114) were only included in the calculations if the records coincide with the zoogeographic information given by
Ninety seven (97) species in our database are reported from all German federal states (Saarland as the smallest state - 2568.7 km² - only facultatively) and additionally from at least four other Central European countries.
Not surprisingly, as an example of a “common” species we present the distribution data of the Cereal Leaf Beetle,
We present this map in spite of the difficult species identification because there is no other species in the database represented by more records. Thus, these records give the clearest picture of a “widespread” species that is deemed to be “common everywhere” in the literature and illustrates the importance of accurate identifications. (See
Distribution map of
The distribution of 103 species has a northern border between 50°N and 53°N approximately parallel to the latitude. As an example we present the map of the flea beetle
Thirty seven (37) of our 50 records have been either originally identified or later verified by experts on Central European flea beetles (Manfred Döberl, Uwe Heinig, Karl-Heinz Mohr, Dieter Siede). Therefore, we chose this species as an example although it belongs to a group of species in the genus
Distribution map of
Fifty two (52) species had their northern boundary between 51°N and 55°N, stretching from South-West to North-East. As an example we present the map of
Distribution map of
Twelve species are found only in the south-western part of the study area. Their range extended north between 50° and 54°, while the boundary stretches from North-West to South-East.
Distribution map of
Eight of the listed species are distributed north of 49°N or the abundance of which decreases remarkably between 53°N and 49°N. An example of these species is
Distribution map of
Of the 647 species analysed, 16 had a western distribution boundary between 10°E and 14°E. As an example we present the distribution map of
Distribution map of
52 species occurred only in areas south of 51°N and east of 10°E. The Five-spotted Asparagus Beetle
Distribution map of
Only five species were reported exclusively from areas south of 51°N and west of 10°E. One of them is the seed beetle
Distribution map of
Of the studied species, 37 showed a surprising distribution pattern. These species are reported from all over Central Europe, but have a remarkable gap, in most cases in Central Germany, Southeast Germany and/or the Alpine region. These gaps cannot plausibly be explained by selective collecting, as congeneric species are reported from these gaps. An example of such a pattern is
Distribution map of
Eighteen (18) species are distributed in montane areas, i. e. between 200 m and 1500 m a. s. l. As an example we present the distribution map of
Distribution map of
Distributions restricted to alpine areas, i. e. regions comprising peaks of more than 1500 m a. s. l., were characteristic of 28 species. The example chosen here is
Distribution map of
As “scattered” we define a pattern of few (less than 25) records which are seemingly distributed at random over the map. This is the case in 53 species,
Distribution map of
Fifty (50) species show a distribution with a marked pattern, which can, however, not plausibly be explained by referring to known patterns. In
Distribution map of
The types of geographic distributions we distinguish are represented by remarkably different numbers of species, which is shown in
Relative frequency of distribution types of Chrysomelidae in Central Europe.
A first, and unexpected, result of the present study was that the distribution patterns of those 532 species of which we have more than 10 records in our file are not all different or all similar but can easily be grouped into eleven distinct types (widely distributed, southern, south-eastern, south-western, northern, eastern, south-east quarter, south-west quarter, fragmented, montane, and alpine, plus two less distinct forms: irregular and scattered). As it is normal for patterns in nature, there are cases in which the geographical limits are less sharp than the circumscription of the “types” could suggest. But even in these cases, the frequency maps allow for clear assignment of a species pattern to a distribution type, which means that only few records from the edge of a presumed distribution area lie beyond the defining borders.
A second and also remarkable result is that the eleven rather distinct types correspond to zoogeographic patterns described in literature, e.g. in
Although in numerous cases it is tempting to regard our results as true reflections of real distribution patterns, several caveats must be considered:
(1) As our target area comprises 1291 or at least 1126 grid cells, and we aim at judging on the geographical distribution of 647 species (or ideally 787), it is entirely clear that 63.000 records are definitely too few to allow for justified conclusions. A rough estimate shows that for coverage of 100 records per grid cell and species we would need more than 83 million records. Even if we assume that not all species occur in all grid cells and that less than 100 records would be sufficient, more than 10 million records is a sound estimate for a database meeting all our desires.
(2) Collecting activity of private and professional entomologists is strongly influenced – and was so even more in the past – by political borders and (restricted) freedom to travel. This factor can easily lead to erroneous conclusions on beetle distribution in Central Europe.
(3) An unknown but possibly considerable number of specimens in private and museum collections may be incorrectly determined. This applies more to museum collections than to private ones, since museum curators and collection managers are normally not taxonomic experts of all the taxa they are responsible for. Thus, as many museum specimens come from donations of uncertain taxonomic reliability, or from samples from student projects in the field etc., there are countless causes of mis-identification. These could be detected by the taxonomic specialists in our group in a limited number of cases only. In case of a doubtful record voucher specimens were revised when it was possible. Despite to our effort, a certain degree of uncertainty remains.
(4) There is some arbitrariness in the assignment of a “distribution type”. Although we tried to define these types as clear as possible, we had to cope with cases in which all records but one or extremely few fit into one of our types, and in which we decided to ignore these “aberrant” records (as e.g., with
(5) Similar as above, additional records may lead to a distribution type different from the one we assigned. This was already the case when 9656 additional records were entered into the database after one of us (T.R.) had completed his diploma thesis in 2008 (“Historisch-zoogeographische Analyse der rezenten Verbreitung der Blattkäfer (
(6) Data density varies extremely with respect to species and areas, as can be seen from
For the purpose of the present paper the only relevant aspect of the records labelled “
Despite these limitations, of which most have been discussed by
The fact that so many species (34.8 %) are distributed in the southern part of our study area (
The distribution data of most species fit remarkably well to the faunistic literature. For some cases, however, we have no plausible explanation at hand, other cases differ from published statements.
As stated above, more data are needed. However, except for few special cases, no additional collecting in the field is necessary. Our experience in the course of the present study is that private and museum collections harbour enough data to backfill our database up to the intended amount. Thus, we are confident that we can retrieve this buried treasure of knowledge with joint effort.
The present paper is based on the diploma thesis of the second author. We thank all those colleagues who handed in their records, several helpers who entered additional data into the database and an anonymous referee for linguistic and substantial improvement of our manuscript.
List of species, assigned to the distribution types.
Species of which we have less than 10 records (116):
Widely distributed species (97):
Southern distribution (103):
South-Eastern (52):
South-Western (12):
Northern (8):
Eastern (16):
South-East quarter (52):
South-West quarter (5):
Fragmented (37):
Montane (18):
Alpine (28):
Scattered (53):
Unusual (50):