Inventory of the terrestrial isopods in Belgium (2011-2020)

Study Extent

Inventory of the terrestrial isopods in Belgium (2011-2020) is an initiative of Spinicornis (Terrestrial Isopod Research Group of Belgium) with cooperation of the Research Institute of Nature and Forest (INBO) & Natuurpunt Studie. The project started in 2014 and stated as goal to survey every 10km X 10km square of the UTM (Universal Transverse Mercator Projection) grid in Belgium. The observations made within this project are complemented with citizen science data (point data) from the nature observation websites http://www.waarnemingen.be and https://www.observations.be from 2011 until 2020. All observations were validated based on pictures by the members of Spinicornis. Additional data was collected by identifying specimens from multiple surveys between 2011 and 2020 where pitfall traps or other trap types had been used.

Sampling

In every Belgian UTM 10km square, three different habitats (if present) were checked for terrestrial isopods: a deciduous forest, a river or stream side and an anthropogenic habitat (garden, park, graveyard, etc.). Disused stone quarries or coastal habitats were also visited if present. The vast majority of the observations originate from field observations where terrestrial isopods were collected by hand or photographed. A minority comes from pitfall traps or other trap types (e.g. sugar bait traps). The project of Spinicornis was finished at the beginning of 2020 and resulted in an ecological atlas of the terrestrial isopods of Belgium (De Smedt et al. 2020). The majority of the data are presence-only data (absence data are not included in this dataset).

Quality Control

Records were collected by both terrestrial isopod experts and volunteers. Observations by volunteers were only included in the database after being validated by experts of Spinicornis based on photographs of their observations.

Method steps

1. Spinicornis members sampled different habitats in all squares of the UTM 10 x 10 km² grid in Belgium and entered the observations in waarnemingen.be / observations.be. These portals are managed by Natuurpunt Studie and Natagora respectively, but use the same underlying database system.
2. Spinicornis members identified specimens observed and collected. The data records were subsequently imported in the waarnemingen.be database.
3. Spinicornis also validated observations entered by volunteers in waarnemingen.be and observations.be between 2011 and 2020.
4. A custom SQL view is created in the database to map the original data to Darwin Core as an occurrence core.
5. A delimited file was created and exported from the waarnemingen database.
6. The generated Darwin Core file was imported in the INBO IPT and documented with metadata.
7. The dataset is published and registered with GBIF.

The dataset covers data from 35 native species of terrestrial isopods (Order Isopoda, Suborder Oniscidea) found in Belgium between 2011 and 2020. Also included are records for 3 multispecies for which identification was not possible based on photographs or for samples lacking males.

1. Animalia
   common name: animals rank: kingdom
2. Arthropoda
   rank: phylum
3. Malacostraca
   rank: class
4. Isopoda
   common name: isopods rank: order
5. Oniscidea
   rank: suborder
6. Crustacea
   rank: subphylum
7. Ligiidae
   rank: family
8. Trichoniscidae
   rank: family
9. Styloniscidae
   rank: family
10. Oniscidae
    rank: family
11. Philosciidae
    rank: family
12. Platyarthrus
    rank: family
13. Armadillidiidae
    rank: family
14. Armadiliidae
    rank: family
15. Cylisticidae
    rank: family
16. Porcellionidae
    rank: family
17. Trachelipodidae
    rank: family
18. Androniscus dentiger
    rank: species
19. Armadillidium album
    rank: species
20. Armadillidium nasatum
    rank: species
21. Armadillidium opacum
    rank: species
22. Armadillidium pictum
    rank: species
23. Armadillidium pulchellum
    rank: species
24. Armadillidium vulgare
    rank: species
25. Cylisticus convexus
    rank: species
26. Eluma caelata
    rank: species
27. Haplophthalmus danicus
    rank: species
28. Haplophthalmus mengii
    rank: species
29. Haplophthalmus montivagus
    rank: species
30. Hyloniscus riparius
    rank: species
31. Ligia oceanica
    rank: species
32. Ligidium hypnorum
    rank: species
33. Metatrichoniscoides leydigii
    rank: species
34. Oniscus asellus
    rank: species
35. Philoscia affinis
    rank: species
36. Philoscia muscorum
    rank: species
37. Platyarthrus hoffmannseggii
    rank: species
38. Porcellio dilatatus
    rank: species
39. Porcellio laevis
    rank: species
40. Porcellio monticola
    rank: species
41. Porcellio scaber
    rank: species
42. Porcellio spinicornis
    rank: species
43. Porcellionides pruinosus
    rank: species
44. Porcellium conspersum
    rank: species
45. Trachelipus rathkii
    rank: species
46. Trichoniscoides albidus
    rank: species
47. Trichoniscoides helveticus
    rank: species
48. Trichoniscoides sarsi
    rank: species
49. Trichoniscus alemannicus
    rank: species
50. Trichoniscus provisorius
    rank: species
51. Trichoniscus pusillus
    rank: species
52. Trichoniscus pygmaeus
    rank: species
53. Haplophthalmus danicus/mengii/montivagus
    rank: unranked
54. Trichoniscus pusillus/provisorius/alemannicus
    rank: unranked
55. Trichoniscoides sarsi/helveticus
    rank: unranked

Belgium is a small country (ca. 30.500 km²) in Western Europe. It has a short shoreline (approx. 65 km) along the North Sea. The country is part of two European biogeographical regions, namely the Atlantic and the Continental region. The Atlantic region is largely covered by agricultural land and urban areas. The Continental region is less covered by agricultural land and urban areas and is instead more forested. Despite its small size, Belgium has a rich geology going from a flat Atlantic region in the west consisting of Holocene and Pleistocene deposits to a Continental hilly landscape with Mesozoic and Pleistocene deposits in the east and the south. The Atlantic region has clay loam and heavy clay soils in the northwest, and loam and sandy loam soils in the middle with a relatively high terrestrial isopod diversity. On the sandy soils in the northeast of the Atlantic region, terrestrial isopod diversity is rather low. The Continental region contains two bands of soils with calcareous outcrops, with a high species richness of terrestrial isopods. In between these chalky soil bands and in the east of the country, the land is covered by slate and sandstone soils, some with large areas of peatlands, which are more species poor.