Haplophthalmus mengii (Zaddach, 1844)

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 : 20

5. Haplophthalmus mengii (Zaddach, 1844)

( Fig. 7 , Fig. 11 c , Map 6 , Table 8)

Similar to the other Haplophthalmus -species H. mengii is found in a wide variety of landscapes and habitats. Compared to H. danicus and H. montivagus , the species was less frequently observed in graveyards, parks and gardens. Since the species is only occasionally found in anthropogenic habitats and the records are not clustered in a certain geographic region, we cannot consider the species a synanthropic species, as in the Netherlands ( BERG et al., 2008). Depending on the habitat type the species is more or less bound to water. In anthropogenic habitats only 12.5% of the observations were near streams, rivers and canals ( Table 8). In forest habitat, this rate rises to 42.5% and in open landscapes even to 76%. Records in open landscape are mostly limited to the polder and sand-loam ecological region ( Map 6 ). In Southern Belgium, the species is mostly found in forests and categorized as a species with strong forest affinity ( DE SMEDT et al., 2020b).

The number of observations of H. mengii in forest habitat throughout the year is more or less constant ( Fig. 7 ), possibly due to the more stable moisture conditions in forest habitat. The number of observations is however strongly reduced during summer months in open landscapes. In open habitat types the species is mostly found near water and so during summer months they probably crawl deeper into the soil because of lower soil humidity.

Figures

Map 6. Distribution map for Haplophthalmus mengii.

Figure 7. Corrected number of observations per two-month period for Haplophthalmus mengii (N = 87).

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.