Haplophthalmus montivagus Verhoeff, 1941

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 : 22

6. Haplophthalmus montivagus Verhoeff, 1941

( Fig. 8 , Map 7 , Table 9)

Haplophthalmus montivagus closely resembles H. mengii ( Fig. 11 c ) and was only discovered for the first time in Belgium in 2006 ( LOCK, 2007). Despite the close resemblance to H. mengii , it has a very different habitat use. It has a more southern distribution than H. mengii and is more frequently found in anthropogenic habitat. It is less confined to forests and open landscapes compared to H. mengii . In anthropogenic habitat, only 10.6% of locations were close to water but in forests H. montivagus is clearly bound to water, with 67.9% of records made at ditches and stream and river banks ( Table 9). This is higher than for H. mengii (42.5%).

For the anthropogenic habitat, the lowest number of records was in January–February, followed by the highest number in March–April ( Fig. 8 ). In May–June H. montivagus was slightly less observed than in the months July until December. This is a similar pattern compared with Androniscus dentiger , a species with a very similar number of observations in anthropogenic habitats and graveyards in particular (92 records and 68.5% in graveyards). In forests, the lowest corrected number of records is for the months January–February, which can probably be attributed to low temperatures and higher amount of frosty days in those months in southern Belgium. For September–October, it is less clear why the corrected number of records is rather low in forests.

Figures

Map 7. Distribution map for Haplophthalmus montivagus.

Fig. 8. Corrected number of observations per two-month period for Haplophthalmus montivagus (N = 157).

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.