Trichoniscoides sarsi Patience, 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 : 34

12. Trichoniscoides sarsi Patience, 1908

( Fig. 14 , Map 12 , Table 14)

Trichoniscoides sarsi is closely related and morphologically very similar to T. helveticus ( Fig. 11 g ) but its habitat and activity patterns resemble more T. albidus . It is common in coastal habitat and open landscape, with an important share of these records situated in the polders ecological region ( Map 12 ). As T. albidus , further inland the species is more frequently found in forests and anthropogenic habitats and it seems to avoid sandy soil types. However, in contrast to T. albidus , anthropogenic habitat and open landscape are more important for T. sarsi ( Table 14) while forests are more important for T. albidus . Compared to T. helveticus , T. sarsi is less bound to water in forest habitat (36.4% compared to 76.9% for T. helveticus ), but again comparable to T. albidus (42.4% of forest locations are near water). In anthropogenic habitat, the species is most frequently found in graveyards. There is very few overlap in the distribution of T. sarsi and T. helveticus in Belgium, which is observed in other countries as well (BERG, 2008). There is only one known location where both species co-occurred i.e. a graveyard in the centre of the country.

Trichoniscoides sarsi is mostly recorded from November until February in all habitat types ( Fig. 14 ). Like most small and drought-sensitive species it retreats deeper into the soil when soil moisture levels are lower in warmer months.

Figures

Map 12. Distribution map for Trichoniscoides sarsi.

Fig 14. Corrected number of observations per two-month period for Trichoniscoides sarsi (N = 79).

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.