Georissa is a genus of minute land snails, terrestrial gastropod mollusks in the family Hydrocenidae.MolluscaBase eds. (2025). MolluscaBase. Georissa W. T. Blanford, 1864. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=818273 on 2025-04-21
Description (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.
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.Schilthuizen M., Rutten E. J. M. & Haase M. (2012). "Small-scale genetic structuring in a tropical cave snail and admixture with its above-ground sister species". Biological Journal of the Linnean Society 105: 727-740. doi:10.1111/j.1095-8312.2011.01835.xSchilthuizen M., Cabanban A. S. & Haase M. (2005). "Possible speciation with gene-flow in tropical cave snails". Journal of Zoological Systematics 43: 133-138. .
Species Species within the genus Georissa include:
Georissa anyiensis Khalik, Hendriks, Vermeulen & Schilthuizen, 2018 Georissa bangueyensis E. A. Smith, 1895 Georissa bauensis Khalik, Hendriks, Vermeulen & Schilthuizen, 2018 Georissa biangulata Quadras & Möllendorff, 1894 Georissa borneensis E. A. Smith, 1895 Georissa elegans Quadras & Möllendorff, 1894 Georissa everetti E. A. Smith, 1895 Georissa filiasaulae Haase & Schilthuizen, 2007Haase M. & Schilthuizen M. (2007). "A new Georissa (Gastropoda: Neritopsina: Hydrocenidae) from a limestone cave in Malaysian Borneo". Journal of Molluscan Studies 73(3): 215-221. . Georissa gomantongensis E.A. Smith, 1894 Georissa hadra Thompson & Dance, 1983 Georissa hosei Godwin-Austen, 1889 Georissa japonica Pilsbry, 1900Noseworthy R. G., Lim N.-R. & Choi K.-S. (2007). "A Catalogue of the Mollusks of Jeju Island, South Korea". Korean Journal of Malacology 23(1): 65-104. PDF. Georissa kinabatanganensis Khalik, Hendriks, Vermeulen & Schilthuizen, 2018 Georissa kobelti Gredler, 1902 Georissa laevigata Quadras & Möllendorff, 1894 Georissa laseroni (Iredale, 1937) Georissa mawsmaiensis Das & Aravind, 2021 Georissa monterosatiana Godwin-Austen & Neville, 1879 Georissa muluensis Khalik, Hendriks, Vermeulen & Schilthuizen, 2018 Georissa niahensis Godwin-Austen, 1889 Georissa pachysoma Vermeulen & Junau, 2007 Georissa purchasi Georissa pyrrhoderma Thompson & Dance 1983 Georissa pyxis (Benson, 1856) - type species of the genus Georissa Georissa rufula von Möllendorf, 1900 Georissa saulae (van Benthem-Jutting, 1966) Georissa scalinella (van Benthem-Jutting, 1966) Georissa semisculpta Georissa sepulutensis Khalik, Hendriks, Vermeulen & Schilthuizen, 2018 Georissa shikokuensis Amano, 1939 Georissa silaburensis Khalik, Hendriks, Vermeulen & Schilthuizen, 2018 Georissa similis E.A. Smith, 1894 Georissa vesta Thompson & Dance, 1983 Georissa williamsi Godwin-Austen, 1889 (including Georissa hungerfordi)
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