Porcellio laevis Latreille, 1804

Boeraeve, Pepijn, Arijs, Gert, Segers, Stijn, Smedt, Pallieter De, Spinicornis & Utm, Belgium. Every grid cell of the, 1908, Habitat and seasonal activity patterns of the terrestrial isopods (Isopoda: Oniscidea) of Belgium, Belgian Journal of Entomology 116, pp. 1-95 : 72

30. Porcellio laevis Latreille, 1804

( Fig. 2 h , Fig. 34 , Map 30 , Table 32)

Recent records of Porcellio laevis in Belgium are restricted to old farms. It has a much narrower niche compared to P. dilatatus . The two only recent records are from active horse stables. The species was recorded underneath hay, stones and dung in a corner of the stable. When a resurvey of old locations from the early 1990’s ( BOON et al., 1993) was undertaken, it turned out that in most locations the species was not present anymore, but also the farms were not active anymore. Probably, as a thermophilic species, it needs the constant warmer temperatures caused by livestock like cows and horses. It is one of the rarest species in Belgium and according to DE SMEDT et al. (2020a) it risks disappearing in Belgium, a trend that is also reported from the UK ( HARDING, 2016).

The two recent records are from May 2015 and November 2019. Like P. dilatatus , P. laevis is probably year-round active in (horse) stables with livestock but because of the few observations, no conclusions can be drawn from the phenology diagram ( Fig. 34 ).

Figures

Map 30. Distribution map for Porcellio laevis.

Fig. 2. a, Ligia oceanica; b, Haplophthalmus danicus; c, Miktoniscus patience; d, Trichoniscus pygmaeus; e, Armadillidium pictum; f, Armadillidium vulgare; g, Porcellio dilatatus; h, Porcellio laevis.

Fig. 34. Corrected number of observations per two-month period for Porcellio laevis (N = 2).