Hyloniscus riparius (C. Koch, 1838)

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 : 24

7. Hyloniscus riparius (C. Koch, 1838)

( Fig. 9 , Fig. 11 d , Map 8 , Table 10)

In Belgium, Hyloniscus riparius reaches its western border of its distribution in Europe. DE SMEDT et al. (2020a) conclude that the species has relatively recently appeared in Belgium, mostly based on its absence in museum collections ( DE SMEDT et al., 2018b). Therefore, the species may still be expanding its distribution in Belgium to the west. The species is also expanding its range on a European scale from its original distribution in Central and Eastern Europe ( SCHMALFUSS, 2003) to further west in France ( SÉCHET et al., 2012). In the east, H. riparius has reached Russia ( GONGALSKY et al., 2013).

The species is mostly found in forests and in anthropogenic habitats ( Table 10) but some observations were also made in open landscape. In the western part of Belgium, H. riparius is still rare, with an important number of observations in anthropogenic habitat, in contrast to the eastern part of Belgium where most records are from forests ( Map 8 ). H. riparius has a very high inundation resistance ( OOMS et al., 2020) and is frequently found close to water, however there is a large difference in its affinity to water based on habitat type. In forests, 65.3% of records were near water whereas in anthropogenic habitats this rate stands at only 24.1% ( Table 10).

H. riparius is in anthropogenic habitats mostly observed from September until December, with considerably lower numbers of records from January until August ( Fig. 9 ). In forests, the corrected number of records is highest in May–June followed by November–December but it is unclear why detection is so much higher compared to other months.

Figures

Map 8. Distribution map for Hyloniscus riparius.

Fig. 9. Corrected number of observations per two-month period for Hyloniscus riparius (N = 132).

Fig. 11. a, Ligidium hypnorum; b, Androniscus dentiger; c, Haplophthalmus mengii; d, Hyloniscus riparius; e, Metatrichoniscoides leydigii; f, Trichoniscoides albidus; g, Trichoniscoides helveticus; h, Trichoniscus provisorius.