Trichoniscoides helveticus (Carl, 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 : 32

11. Trichoniscoides helveticus (Carl, 1908)

( Fig. 11 g , Fig. 13 , Map 11 , Table 13)

A small, soil-dwelling species with only a scarce number of records in Belgium. The species is nearly absent in open landscape. Forests are an important habitat for T. helveticus and most (76.9%) records in forests are made near ditches and along streams ( Table 13). Not surprising since this species has, together with the next species, one of the lowest desiccation resistance values of all native species ( DIAS et al., 2013). The anthropogenic habitat is of equal importance to forests with 51.7% of the records (44.8% for forest). In anthropogenic habitat, the species is less dependent on the proximity of water, with only 13.3% of the records near water in anthropogenic habitat.

Trichoniscoides helveticus is, similar to most soil-dwelling and drought-sensitive species, more observed during winter months ( Fig. 13 ). In forest habitat, the most important months are from November until April but in anthropogenic habitat most records are from September through February. Due to the limited number of records, it is uncertain whether this represents a true shift.

Figures

Map 11. Distribution map for Trichoniscoides helveticus.

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.

Fig. 13. Corrected number of observations per two-month period for Trichoniscoides helveticus (N = 32).