Zospeum tholussum

Zospeum tholussum
The shells of living specimens of Zospeum tholussum are translucent
Conservation status
Near Threatened  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Heterobranchia
Order:	Ellobiida
Family:	Ellobiidae
Genus:	Zospeum
Species:	Z. tholussum
Binomial name
Zospeum tholussum Weigand, 2013

Zospeum tholussum or the domed land snail,^[2] is a cave-dwelling species of air-breathing land snails in the family Ellobiidae. It is a very small species, with a shell height of less than 2 mm (0.08 in) and a shell width of around 1 mm (0.04 in). Z. tholussum individuals are completely blind and possess translucent shells with five to six whorls. The second whorl of their shells has a characteristic dome-like shape. They are also extremely slow-moving and may depend on passive transportation through running water or larger animals for dispersal.

Zospeum tholussum was discovered at depths of 743 to 1,392 m (2,438 to 4,567 ft) in the Lukina jama–Trojama cave system in Croatia in 2012, during a caving expedition. It was formally described as a new species in 2013 by the taxonomist Dr. Alexander M. Weigand.

On 22 May 2014 International Institute for Species Exploration declared the snail as one of the "Top 10 New Species of 2014" among species discovered in 2013. The reason for its selection is its habitat in complete darkness of a cave some 900 meters below the surface. It lacks eyes and its shell is transparent giving it a ghost-like appearance.^[3][4]