Omphiscola glabra

Omphiscola glabra, commonly known as the pond mud snail,^[3] is a species of small to medium-size, air-breathing, freshwater snail, an aquatic pulmonate gastropod mollusk in the family Lymnaeidae.^[4] Omphiscola glabra is the type species of the genus Omphiscola.^[5]

Omphiscola glabra
A live individual of Omphiscola glabra on a paper grid, scale bar 1 cm
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Superorder:	Hygrophila
Family:	Lymnaeidae
Genus:	Omphiscola
Species:	O. glabra
Binomial name
Omphiscola glabra (Müller, 1774)[1]
Synonyms
Buccinum glabrum[2] Lymnaea glabra[2] Stagnicola glaber[2]

Distribution

This European snail can be found from southern Scandinavia (61° N) to southern Spain.^[6]

• endangered in Germany. Critically endangered in Western Germany (Rheinland-Pfalz, Saarland, Nordrhein-Westfalen, Hessen). Extinct in Bavaria.^[6]
• Netherlands
• one site in the south east of Ireland was found in 2009, but it is listed as extinct on the local Red List (2009).^[7]
• vulnerable in Great Britain^[6]

The distribution of Omphiscola glabra is very scattered and rare.^[6] It is seriously threatened, and has become locally extinct in many places.^[6] It is threatened by continuing habitat destruction because of drainage and intensive farming.^[6] Acriculturally induced eutrophication is also a threat. Omphiscola glabra has disappeared widely from urbanized areas such as London.^[6]

Drawing of the shell.

Shell description

The shell is strongly cylindrical, horny, often with a brownish or blackish surface, the apex is blunt, 7–8 moderately convex whorls, with last whorl being twice as high as the narrow aperture, and with aperture often with white lip.^[6]

The height of the shell is 9–12 mm,^[6] up to 15 mm^[8] or up to 20 mm.^[6] The width of the shell is 3–4 mm,^[6] up to 5.5 mm.^[8]

Five shells of Omphiscola glabra

Habitat

This snail lives in places such as swampy meadows and ditches.^[9]

Omphiscola glabra is said to occur in small areas of standing water that have a lot of vegetation such as swamps, and also in standing forest waters with leaf litter, often in water with organic iron contents and low calcium contents.^{[6][clarification needed]}

In Central France, the populations of Omphiscola glabra are currently declining because its habitat is threatened by modern agricultural practices.^[10]

In Britain however, this species occurs in small standing waters that are low in nutrients, with poor aquatic flora, often in waters drying out periodically.^[6] They usually do not occur in habitats with high molluscan diversity, and usually in habitats on uncultivated land.^[6] They are calciphile and have a pH tolerance of 5.4–8.8.^{[6][clarification needed]}

Reproduction begins in May.^[6] Juveniles hatch after 15–25 days.^[6] Omphiscola glabra has two generations per year.^[6]

Parasites

Omphiscola glabra can serve as an intermediate host for several digenean trematodes. In France, Omphiscola glabra is naturally infected with Fasciola hepatica,^[11] Calicophoron daubneyi,^[12] and Haplometra cylindracea;^[13] in all, seven digenean species parasitize O. glabra in the Brenne Regional Natural Park, central France.^[14] Moreover, a report suggests that the species is also susceptible to Fascioloides magna infection.^[15]