Georissa
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| Georissa | |
|---|---|
 | |
| Georissa shikokuensis | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Order: | Cycloneritida |
| Family: | Hydrocenidae |
| Genus: | Georissa Blanford, 1864[1] |
| Synonyms | |
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Georissa is a genus of minute land snails, terrestrial gastropod mollusks in the family Hydrocenidae.[2]
(Original description in Latin) The shell is imperforate or scarcely perforate. It is very small, and conical, displaying an amber-colored or reddish hue. It is usually spirally grooved or striated.
The operculum appears semi-oval, lacking any trace of spiral structure, and presents eccentric striations. It is testaceous (shell-like) and transparent.
The animal is small and is equipped with hemispherical lobes in place of tentacles. Its eyes are normal, and its foot is short and rounded.[3]
Distribution
Although the species are best known for living on the surface of limestone rocks, they are often also found in and on the vegetation and on non-calcareous rocks. One species, Georissa filiasaulae, is cavernicolous. It is only known from two caves in the Sepulut area of Sabah, Malaysian Borneo, where its above-ground sister species, Georissa saulae, inhabits the rocks outside of the cave, and is connected to the cave snail via narrow zones of hybridization at the cave entrances. Possibly, G. filiasaulae has evolved without ever having been fully separated from its ancestor, a process known as speciation-with-gene-flow.[4][5]
