This species can usually by distinguished from Asellus aquaticus by the continuous pale band along the posterior margin of the head. However, care is needed since head pigmentation can vary and the two species are frequently confused. The shape of the male first pereopod is diagnostic.
Distribution and Habitat
P. meridianus occurs throughout the British Isles, but in many areas it is much less frequently recorded than A. aquaticus.
Although found in similar places to A. aquaticus, it is rarely found in garden ponds, and is much less tolerant of pollution.
This summary is based on the detailed account in Gregory (2009).