Planorbarius metidjensis

Planorbarius metidjensis is a freshwater lung snail.

Experiments confirmed it to be a host of the Schistosoma parasites, while the Bulinus truncatus freshwater snail has been known much longer as a carrier of schistosomiasis.

Description
The snail measures 8 mm x 16 to 18 mm. The shell is light yellowish, while the periostracum is brown, reddish or greenish. The body is nearly black with a grey foot and tentacles.

Schistosomiasis transmission
While P. metidjensis has been successfully infected with Schistosoma haematobium in the laboratory, in Morocco, no free-living infected snails have been found during a survey. Likewise, in the laboratory, snail specimens from Portugal and Salamanca were found to be very susceptible to infections by Schistosoma bovis strains gathered from the Salamanca region, but the 1977 study urged a prevalence survey of free-living snails.

In some areas, there are ''S. haematobium/S. bovis'' hybrids. P. metidjensis is immune to experimental infection with hybrid parasites collected in Corsica that contain 23% genetical material from S. bovis.

Distribution and habitat
The snail occurs in southwestern Morocco as well as in Algarve (Portugal) and Salamanca (Spain).

In a 2007 study carried out in Morocco, the snail was found in larger altitudes, and not in man-made water bodies like canals and artificial lakes. It tolerated a wide range of electrical conductivities (120 to 3650 microsieverts/cm) and up to 1.1 grams of chlorides per liter. It was often found together with Ancylus fluviatilis river snails.