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Corresponding author: Pallieter De Smedt ( pallieter.desmedt@ugent.be ) Academic editor: Stefano Taiti
© 2018 Pallieter De Smedt, Pepijn Boeraeve, Gert Arijs, Stijn Segers.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
De Smedt P, Boerave P, Arijs G, Segers S (2018) Woodlice of Belgium: an annotated checklist and bibliography (Isopoda, Oniscidea). In: Hornung E, Taiti S, Szlavecz K (Eds) Isopods in a Changing World. ZooKeys 801: 265-304. https://doi.org/10.3897/zookeys.801.21894
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Woodlice are key organisms for nutrient cycling in many terrestrial ecosystems; however, knowledge on this invertebrate group is limited as for other soil fauna taxa. Here, we present an annotated checklist of the woodlice of Belgium, a small but densely populated country in Western Europe. We reviewed all 142 publications on Belgian woodlice, the oldest dating back to 1831 and re-identified all doubtful specimens from the Royal Belgian Institute of Natural Sciences (RBINS) collection. These data is complemented with observations from extensive field surveys dating from March 2014 until December 2017. We report 36 species of woodlice with free-living populations for Belgium. Nine species can be added compared to the latest checklist published in 2000 being Hyloniscus riparius (C. Koch, 1838), Miktoniscus patiencei Vandel, 1946, Trichoniscoides sarsi Patience, 1908, Haplophthalmus montivagus Verhoeff, 1941, Porcellio monticola Lereboullet, 1853, Metatrichoniscoides leydigii (Weber, 1880), Trichoniscus alemannicus Verhoeff, 1917, Eluma caelata (Miers, 1877) and Philoscia affinis Verhoeff, 1908. Two species are deleted from the checklist (Ligidium germanicum Verhoeff, 1901 and Armadillidium depressum Brandt, 1833) because records are doubtful and no material has been preserved. Additionally the data of the field surveys is used to determine a species status of occurrence in Belgium. For each species, a short overview of their first records is provided and their confirmation as part of the Belgian fauna, their current status, as well as a complete bibliography of the species in Belgium.
Belgium, macro-detritivores, species distribution, terrestrial isopods
Woodlice (Isopoda: Oniscidea) are amongst the largest representatives of the soil invertebrate community in European terrestrial ecosystems (
A complete overview of the history of woodlice research in Belgium is provided, by checking all existing literature on Belgian woodlice and re-identifying all doubtful or difficult to recognise species present in the collections from the Royal Belgian Institute of Natural Sciences (RBINS). These data are complemented with extensive field surveys carried out from March 2014 until December 2017 in order to produce a new checklist of Belgian woodlice. Additionally the data of the field surveys is used to determine a status of occurrence in Belgium for all species.
The oldest record of woodlice species in Belgium dates back to 1831 (
During the second half of the 19th century, there was a slow increase in the number of publications and recorded species with nine species in 1870 and the first checklist for Belgium (
From the 1910’s to the 1970’s, most woodlouse research in Belgium focused on caves (see e.g. all publications by Leruth in the 1930’s and Kersmaekers in the 1970’s).
At the start of the 21st century, there was a renewed interest in woodlouse research with the discovery of four new species for Belgium by K. Lock (Fig.
Belgium is a rather small country (ca. 30.500 km²) in Western Europe, but despite its small size, the country shows a rich geology (
Literature
All existing literature published or accepted about Belgian woodlice was reviewed if containing distribution data, descriptions, and ecology up to the end of 2017. Our search was based on old bibliographies from Belgium (
Museum collections
All individuals of 18 species present in the collections of the RBINS were re-identified. Armadillidium nasatum, A. opacum, A. pictum, A. pulchellum, Cylisticus convexus, Haplophthalmus danicus, H. mengii, Philoscia muscorum, Porcellium conspersum, Trachelipus rathkii, Trichoniscus pusillus, T. pygmaeus, and Trichoniscoides helveticus were checked because these species can easily be misidentified or because closely resembling species were only discovered many years later. Androniscus dentiger, Porcellio dilatatus, P. laevis, Porcellionides pruinosus, and Trichoniscoides albidus were checked because only very limited knowledge is available for these species on both the historical and current distribution and ecology. Records labelled with Armadillidium album and Trichoniscus provisorius were not present in the collections. Records of Ligia oceanica, Ligidium hypnorum, Oniscus asellus, Platyarthrus hoffmannseggii, Armadillidium vulgare, Porcellio scaber, and P. spinicornis are widespread and easy to recognise therefore they are expected to be correct. This re-identification enabled us to check the presence of all species and to verify literature references.
Field survey and status
Field surveys were carried out over a four-year period from March 2014 until December 2017 by the authors together with other volunteers from “Spinicornis”. During these surveys, firstly searches for all known Belgian species on locations of old records were carried out, a well as for species that could be expected to occur in Belgium based on their preferred habitat in neighbouring countries.
Secondly, systematic searches of squares of the UTM 10 × 10km grid were carried out in order to map species distribution patterns across Belgium. Main woodlice biotopes were visited in every square. The biotopes visited were (1) an (ancient) forest, (2) a wetland/rivers edge or swamp forest and (3) synantropic habitat (e.g., public park, garden, graveyard…) if present in the 10 km square. These three biotopes cover the habitat niches of most woodlouse species. Additionally, 10 km squares containing a shoreline were surveyed for coastal habitats (e.g., dunes) as well. In some regions, old farms or old quarries have also been visited when present. Woodlice were hand collected by turning stones/dead wood and by sieving the litter layer.
By the end of 2017, the field survey campaign has not been completed but enough data has already been collected to assess the current status of occurrence for all species. In order to give a first indication of the distribution pattern this status is not only determined for the complete territory but also for three different topographical regions. The three regions are roughly based on the Belgian topography with lowlands in the north, hilly landscape in the centre and uplands (up to 694 m) in the south (Fig.
Data of the field surveys were used to assess the status of all species but only observations made in sufficiently surveyed squares were withhold. The criterion for a square to be sufficiently surveyed was at least five species recorded in the square. In some parts of Belgium this is about the maximum number of species that can be found so a higher lower-limit would exclude well-searched squares in those parts of Belgium. Records from heated greenhouses and of specimens only identified to genus-level were removed from the dataset. The resulting dataset contains 5110 records from March 2014 until December 2017.
For every region, at least 59.6% of the squares have been sufficiently surveyed, with a total of 254 visited squares out of 381 (66.7%) (Table
The status was assessed based on the number of squares of the UTM 10×10 km grid in which the species was recorded compared to the number of squares that have been surveyed. Six different categories are distinguished from “not present” (0% of the squares) to “very common” (more than 31.5% of the squares) (Table
Number of squares of the UTM 10×10 km grid per region and number and percentage of squares surveyed between March 2014 and December 2017.
Region | squares in region | squares surveyed | |
# | % | ||
North | 127 | 89 | 70.1 |
Centre | 140 | 97 | 69.3 |
South | 114 | 68 | 59.6 |
Total | 381 | 254 | 66.7 |
Number of records per region and per three-month period, corresponding with the seasons of the year.
North | Centre | South | Total | |
December – February (Winter) | 525 | 617 | 174 | 1316 |
March – May (Spring) | 472 | 395 | 164 | 1031 |
June – August (Summer) | 237 | 469 | 428 | 1034 |
September – November (Autumn) | 727 | 624 | 378 | 1729 |
Total | 1961 | 2005 | 1144 | 5110 |
Since 1831, seven checklists have been published about Belgian woodlice (
Family Ligiidae
1. Ligia oceanica (Linnaeus, 1767)
2. Ligidium hypnorum (Cuvier, 1792)
Family Trichoniscidae
3. Androniscus dentiger Verhoeff, 1908
4. Haplophthalmus danicus Budde-Lund, 1880
5. Haplophthalmus mengii (Zaddach, 1844)
6. Haplophthalmus montivagus Verhoeff, 1941
7. Hyloniscus riparius (C. Koch, 1838)
8. Metatrichoniscoides leydigii (Weber, 1880)
9. Miktoniscus patiencei Vandel, 1946
10. Trichoniscoides albidus (Budde-Lund, 1880)
11. Trichoniscoides helveticus (Carl, 1908)
12. Trichoniscoides sarsi Patience, 1908
13. Trichoniscus alemannicus Verhoeff, 1917
14. Trichoniscus provisorius Racovitza, 1908
15. Trichoniscus pusillus Brandt, 1833
16. Trichoniscus pygmaeus Sars, 1898
Family Styloniscidae
* Cordioniscus stebbingi (Patience, 1907)
Family Oniscidae
17. Oniscus asellus Linnaeus, 1758
Family Philosciidae
18. Philoscia affinis Verhoeff, 1908
19. Philoscia muscorum (Scopoli, 1763)
Family Platyarthridae
20. Platyarthrus hoffmannseggii Brandt, 1833
* Trichorhina tomentosa (Budde-Lund, 1893)
Family Armadillidiidae
21. Armadillidium album Dollfus, 1877
22. Armadillidium nasatum Budde-Lund, 1885
23. Armadillidium opacum (C. Koch, 1841)
24. Armadillidium pictum Brandt, 1833
25. Armadillidium pulchellum (Zencker, 1798)
26. Armadillidium vulgare (Latreille, 1804)
27. Eluma caelata (Miers, 1877)
Family Armadillidae
* Reductoniscus costulatus Kesselyák, 1930
Family Cylisticidae
28. Cylisticus convexus (De Geer, 1778)
Family Porcellionidae
29. Porcellio dilatatus Brandt, 1833
30. Porcellio laevis Latreille, 1804
31. Porcellio monticola Lereboullet, 1853
32. Porcellio scaber Latreille, 1804
33. Porcellio spinicornis Say, 1818
34. Porcellionides pruinosus (Brandt, 1833)
Family Trachelipodidae
*Nagurus cristatus (Dollfus, 1889)
35. Porcellium conspersum (C. Koch, 1841)
36. Trachelipus rathkii (Brandt, 1833)
During the field surveys, 5110 records of woodlice in Belgium are collected between March 2014 and December 2017. For 35 of the 36 Belgian species there is at least one record in the database (Table
Status categories for the Belgian woodlice, together with the lower and upper limits for the percentage of squares where a species was recorded between March 2014 and December 2017 in a certain region.
Status | No. of squares | Rel. no. of squares |
---|---|---|
Not present | 0 | 0% |
Very rare | 1–5 | < 1.3% |
Rare | 6–15 | 1.3–3.9% |
Rather common | 16–40 | 3.9–10.5% |
Common | 41–120 | 10.5–31.5% |
Very common | > 120 | > 31.5% |
Number of visited squares where a certain species is recorded and their relative occurrence per region and countrywide.
Species | North | Centre | South | Belgium | ||||
---|---|---|---|---|---|---|---|---|
# | % | # | % | # | % | # | % | |
Androniscus dentiger | 9 | 10.1 | 44 | 45.4 | 18 | 26.5 | 71 | 28.0 |
Armadillidium album | 1 | 1.1 | 0 | 0.0 | 0 | 0.0 | 1 | 0.4 |
Armadillidium nasatum | 27 | 30.3 | 46 | 47.4 | 31 | 45.6 | 104 | 40.9 |
Armadillidium opacum | 0 | 0.0 | 7 | 7.2 | 22 | 32.4 | 29 | 11.4 |
Armadillidium pictum | 0 | 0.0 | 11 | 11.3 | 20 | 29.4 | 31 | 12.2 |
Armadillidium pulchellum | 2 | 2.2 | 13 | 13.4 | 12 | 17.6 | 27 | 10.6 |
Armadillidium vulgare | 62 | 69.7 | 53 | 54.6 | 16 | 23.5 | 131 | 51.6 |
Cylisticus convexus | 2 | 2.2 | 0 | 0.0 | 4 | 5.9 | 6 | 2.4 |
Eluma caelata | 3 | 3.4 | 0 | 0.0 | 0 | 0.0 | 3 | 1.2 |
Haplophthalmus danicus | 44 | 49.4 | 29 | 29.9 | 7 | 10.3 | 80 | 31.5 |
Haplophthalmus mengii | 30 | 33.7 | 15 | 15.5 | 4 | 5.9 | 49 | 19.3 |
Haplophthalmus montivagus | 1 | 1.1 | 34 | 35.1 | 37 | 54.4 | 72 | 28.3 |
Hyloniscus riparius | 11 | 12.4 | 26 | 26.8 | 10 | 14.7 | 47 | 18.5 |
Ligia oceanica | 2 | 2.2 | 0 | 0.0 | 0 | 0.0 | 2 | 0.8 |
Ligidium hypnorum | 37 | 41.6 | 63 | 64.9 | 63 | 92.6 | 163 | 64.2 |
Metatrichoniscoides leydigii | 9 | 10.1 | 2 | 2.1 | 0 | 0.0 | 11 | 4.3 |
Miktoniscus patiencei | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 | 0 | 0.0 |
Oniscus asellus | 89 | 100.0 | 92 | 94.8 | 68 | 100.0 | 249 | 98.0 |
Philoscia affinis | 3 | 3.4 | 34 | 35.1 | 10 | 14.7 | 47 | 18.5 |
Philoscia muscorum | 87 | 97.8 | 90 | 92.8 | 62 | 91.2 | 239 | 94.1 |
Platyarthrus hoffmannseggii | 38 | 42.7 | 26 | 26.8 | 18 | 26.5 | 82 | 32.3 |
Porcellio dilatatus | 2 | 2.2 | 4 | 4.1 | 0 | 0.0 | 6 | 2.4 |
Porcellio laevis | 0 | 0.0 | 1 | 1.0 | 0 | 0.0 | 1 | 0.4 |
Porcellio monticola | 0 | 0.0 | 0 | 0.0 | 3 | 4.4 | 3 | 1.2 |
Porcellio spinicornis | 88 | 98.9 | 93 | 95.9 | 65 | 95.6 | 246 | 96.9 |
Porcellio scaber | 65 | 73.0 | 77 | 79.4 | 62 | 91.2 | 204 | 80.3 |
Porcellionides pruinosus | 13 | 14.6 | 7 | 7.2 | 2 | 2.9 | 22 | 8.7 |
Porcellium conspersum | 0 | 0.0 | 4 | 4.1 | 29 | 42.6 | 33 | 13.0 |
Trachelipus rathkii | 37 | 41.6 | 29 | 29.9 | 8 | 11.8 | 74 | 29.1 |
Trichoniscoides albidus | 40 | 44.9 | 20 | 20.6 | 0 | 0.0 | 60 | 23.6 |
Trichoniscoides helveticus | 0 | 0.0 | 10 | 10.3 | 7 | 10.3 | 17 | 6.7 |
Trichoniscoides sarsi | 32 | 36.0 | 15 | 15.5 | 0 | 0.0 | 47 | 18.5 |
Trichoniscus alemannicus | 0 | 0.0 | 1 | 1.0 | 2 | 2.9 | 3 | 1.2 |
Trichoniscus provisorius | 55 | 61.8 | 36 | 37.1 | 7 | 10.3 | 98 | 38.6 |
Trichoniscus pusillus | 69 | 77.5 | 64 | 66.0 | 55 | 80.9 | 188 | 74.0 |
Trichoniscus pygmaeus | 23 | 25.8 | 39 | 40.2 | 14 | 20.6 | 76 | 29.9 |
Although many papers have been published on woodlice, many records remained doubtful and the reference collection at the RBINS contained a considerable number of identification errors. Additionally, the number of species recorded in Belgium was relatively low compared to neighbouring countries. This new checklist adds nine species to the last checklist published only 17 years ago (
Certain exotic species are in Belgium only recorded from greenhouses and do not have free-living populations. These species are discussed in a recent paper dedicated to greenhouse species in Belgium (
Status: Coastal species, rare in the north of the country.
Bibliography:
Status: Very common across the country.
Bibliography:
Expected to occur in Belgium by
Status: Very common in the centre of the country, common in the south and rather common in the north.
Bibliography:
First mentioned from greenhouses by
Status: Very common in het north and common to rather common in the rest of the country.
Bibliography:
First mentioned by
Status: Very common in het north and common to rather common in the rest of the country.
Bibliography: Mai
First reported record of the species was done by
Status: Very common in the centre and south of the country, very rare in the north.
Bibliography:
Discovered in Belgium through pitfall trap research in 1998 (
Status: Common across the country.
Bibliography:
Reported by
Status: Rather common in the north of the country, very rare in the centre and absent from the south.
Bibliography:
Only two sightings of this species are known in Belgium. After its discovery in 1999 (
Status: Coastal species, not recorded during the recent field surveys.
Bibliography:
Expected to occur in Belgium by
Status: Very common in the north of the country, common in the centre but absent from the south.
Bibliography:
First individuals identified by
Status: Absent in the north, rather common in the rest of the country.
Bibliography:
First recorded by
Status: Very common in the north of the country, common in the centre but absent from the south.
Bibliography:
Discovered in 2015 (
Status: Rare in the south of the country, very rare in the centre and absent from the north.
Bibliography: De Smedt et al. (2016b).
First recorded by
Status: Very common in the north and centre of the country, common in the south.
Bibliography:
First mentioned by
The bibliography presented below should be considered as a bibliography for the species complex T. alemannicus/pusillus/provisorius, except for references from 2015 onwards.
Status: Very common across the country.
Bibliography:
Status: Very common in the centre of the country, common in the north and the south.
Bibliography:
One of the first five species mentioned for the fauna of Belgium by
Status: Very common across the country.
Bibliography:
Expected to occur in Belgium by
Status: Very common in the centre of the country, common in the south and rare in the north.
Bibliography:
One of the five first species mentioned for the fauna of Belgium by
Status: Very common across the country.
Bibliography:
First recorded by Mac Leod (1880), and appeared to be common but undersampled (
Status: Very common in the north of the country, common in the centre and south.
Bibliography: Mac Leod (1880),
Discovered by
Status: Coastal species, very rare in the north of the country.
Bibliography:
Expected to occur in Belgium by
Status: Very common in the centre and the south of the country, common in the north.
Bibliography:
First mentioned by
Status: Very common in the south of the country, rather common in the centre and absent in the north.
Bibliography:
Mentioned for the first time for Belgium by
Status: Common in the centre and south of the country, absent from the north.
Bibliography:
Status: Common in the centre and south of the country, and rare in the north.
Bibliography: Preudhomme de Borre (
One of the five first species on the Belgian list (
Status: Very common in the north and the centre of the country, common in the south.
Bibliography:
Discovered for the first time in Belgium in 2016 (
Status: Rare in the north of the country, absent from the centre and the south.
Bibliography:
Expected to occur in Belgium by
Status: Rather common in the south of the country, rare in the north and absent from the centre.
Bibliography:
First mentioned by
Status: Rather common in the centre of the country, rare in the north and absent from the south.
Bibliography:
One of the first five species mentioned for the country by
Status: Very rare in the centre, absent from the rest of the country.
Bibliography:
Expected to occur in Belgium by
Status: Rather common in the south, absent from the rest of the country.
Bibliography:
One of the first five species mentioned for the fauna of Belgium by
Status: Very common across the country.
Bibliography:
First mentioned by
Status: Very common across the country.
Bibliography:
First observations from the 1870’s and first mentioned by
Status: Common in the north of the country, rather common in the centre, and rare in the south.
Bibliography:
First recorded by
Status: Very common in the south of the country, rather common in the centre and absent from the north.
Bibliography:
First mentioned by
Status: Very common in the north of the country, common in the centre and in the south.
Bibliography:
Six species were mentioned on at least one of the previous checklists, but are not present anymore on the current checklist. Most species appeared to be misidentifications or could not be confirmed because material was not preserved and literature citings are incomplete.
Androniscus roseus (C. Koch, 1838) was first mentioned by
Armadillidium depressum Brandt, 1833 was first mentioned by
Armadillidium sulcatum Milne-Edwards, 1840 is a species from northern Algeria (
Armadillidium triviale Schöbl, 1861 mentioned by
Ligidium germanicum Verhoeff, 1901 was mentioned by
Eoniscus simplicissimus Arcangeli was a specimen collected by Leruth (1937) and described as a new species to science in a new genus and family by
Literature on Belgian woodlice in greenhouses is very limited. Only five papers deal with inventories carried out in Belgian greenhouses and they are all from the northern part of the country. Up to date only four exotic species could be confirmed in Belgian greenhouses. They cannot be considered as part of the Belgian woodlice fauna, because of the lack of wild populations, and are not included in this checklist as Belgian species. However, they were included in previous checklists (see e.g.
The first exotic species recorded from Belgian greenhouses is Cordioniscus stebbingi (Patience, 1907) by Bagnall in 1908 from a greenhouse in Brussels.
Greenhouse literature:
Twenty-five percent of the Belgian woodlice species were added on this new checklist and all were discovered the last 20 years, therefore it is still possible that even more species can be discovered in Belgium. Below, some species recorded in neighbouring countries and relatively close to the Belgian border are listed:
– Porcellio gallicus Dollfus, 1904. This species is found to be abundant in small deciduous forest fragments in agricultural areas in the north of France (Landifay-et-Bertaignemont) only 45 km from the Belgian border (
– Porcellio montanus Budde-Lund, 1885. Found in Germany (Wiesbaden) around 100 km from the Belgian border (edaphobase.org). Also reported from Grand Duchy of Luxembourg (
– Androniscus roseus (C. Koch, 1838). A species closely resembling A. dentiger and recorded about 160 km from the Belgian border in Frankfurt (Germany) (edaphobase.org). There the species is reported from riparian habitat and forest fringe communities. The species could be overlooked since its close resemblance to A. dentiger and can be expected in the eastern part of the country.
– Trachelipus ratzeburgi (Brandt, 1833). Another species that could be overlooked in Belgium because of its close resemblance to T. rathkii. The species occurs in all kinds of woodland and the closest records are from Herborn in Germany at 140 km from the Belgian border (edaphobase.org). Therefore, the species could be expected in the east of the country.
– Chaetophiloscia cellaria (Dollfus, 1884). This species has recently been discovered in northern France at three localities of which two at 35 km from the Belgian border (
Three of the last five new species on the Belgian list are large to medium-sized and therefore it is possible that the above-mentioned species are present and awaiting discovery.
With 36 species Belgium now has a comparable amount of species, relative to its size, to neighbouring countries like the Netherlands (33 species see
We are grateful to Yves Samyn and Wouter Dekoninck for giving us access to the collections of the RBINS. Oliver Mechthold is thanked for the help with fieldwork.
The list below represents the bibliography of Belgian woodlice with other references used in the text: these other references not dealing directly with Belgian woodlice are indicated with an asterisk [*].