Philoscia affinis Verhoeff, 1908

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 : 48

18. Philoscia affinis Verhoeff, 1908

( Fig. 19 b , Fig. 22 , Map 18 , Table 20)

Discovered for the first time in Belgium in 2014 ( BOERAEVE et al., 2017), since then Philoscia affinis has been recorded in most parts of the country ( Map 18 ). Almost exclusively found in deciduous forests ( Table 20). In the northern part of the country, the species is a good indicator of ancient forests ( DE SMEDT & VANDEKERKHOVE, 2020) and it was categorized as a species with a strong affinity to closed forest habitat ( DE SMEDT et al., 2020b). Most of the records are from forests dominated by Oak trees ( Quercus petraea /robur), sometimes mixed with beech ( Fagus sylvatica ) and hornbeam ( Carpinus betulus ) ( BOERAEVE et al., 2017). It is only found twice in Black Alder ( Alnus glutinosa ) dominated forest ( BOERAEVE et al., 2017). Besides the records in forest habitat, the species has been recorded twice from gardens. However, both gardens were bordering forest habitat.

Despite being considered of Mediterranean origin ( VANDEL 1962), P. affinis is more often recorded during winter months ( Fig. 22 ). It is a rather drought-sensitive species (unpublished data) and this could possibly explain the observed pattern since the species retreat deeper in the litter layer (or soil) when temperatures are high.

Figures

Map 18. Distribution map for Philoscia affinis.

Fig. 19. a, Oniscus asellus; b, Philoscia affinis; c, Philoscia muscorum; d, Platyarthrus hoffmannseggii; e, Armadillidium album; f, Armadillidium nasatum; g, Armadillidium opacum; h, Armadillidium pulchellum.

Fig. 22. Corrected number of observations per two-month period for Philoscia affinis (N = 81).