Georissa

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Georissa
Georissa shikokuensis 001.jpg
Georissa shikokuensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Neritimorpha
Order: Cycloneritida
Family: Hydrocenidae
Genus: Georissa
Blanford, 1864 [1]
Synonyms
  • ChondrellaPease, 1871 (original rank)
  • Georissa (Chondrella)Pease, 1871 alternative representation
  • Georissa (Georissa)W. T. Blanford, 1864 alternative representation
  • Georissa (Georissopsis)Pilsbry & Hirase, 1908 alternative representation
  • Hydrocena (Georissa)W. T. Blanford, 1864
  • OmphalorissaWenz, 1938
  • PetrorissaHabe, 1958

Georissa is a genus of minute land snails, terrestrial gastropod mollusks in the family Hydrocenidae. [2]

Contents

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. [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]

Species

Species within the genus Georissa include:

References

  1. ↑ Blanford W. T. (1864). "On the Classification of the Cyclostomacea of Eastern Asia". Annals and Magazine of Natural History (3)13: 441-465, page 463.
  2. ↑ 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
  3. ↑ Blanford, W.T. (1864). "On the classification of the Cyclostomacea of eastern Asia". nnals and Magazine of Natural History. 3 (13 (78)): 463. Retrieved 21 April 2025.PD-icon.svg This article incorporates text from this source, which is in the public domain .
  4. ↑ 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.x
  5. ↑ Schilthuizen M., Cabanban A. S. & Haase M. (2005). "Possible speciation with gene-flow in tropical cave snails". Journal of Zoological Systematics 43: 133-138. doi : 10.1111/j.1439-0469.2004.00289.133–138.
  6. 1 2 3 4 5 6 Khalik, Mohd Zacaery; Hendriks, Kasper; Vermeulen, Jaap J.; Schilthuizen, Menno (9 July 2018). "A molecular and conchological dissection of the "scaly" Georissa of Malaysian Borneo (Gastropoda, Neritimorpha, Hydrocenidae)". ZooKeys (773): 1–55. Bibcode:2018ZooK..773....1K. doi: 10.3897/zookeys.773.24878 . PMC   6048177 . PMID   30026659.
  7. 1 2 Haase M. & Schilthuizen M. (2007). "A new Georissa (Gastropoda: Neritopsina: Hydrocenidae) from a limestone cave in Malaysian Borneo". Journal of Molluscan Studies73(3): 215-221. doi : 10.1093/mollus/eym020.
  8. ↑ Noseworthy 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.
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