Assiminea grayana

Assiminea grayana, common name the "dun sentinel", is a species of very small (4–6 mm.) salt marsh snail, a terrestrial (or marine gastropod mollusk in the family Assimineidae.^[1]

This species lives in habitats that are intermediate between land and saltwater: in estuaries and salt marshes, at, or right above, the high tide level.^[2]

The 5 mm high x 3 mm. wide shell is semi-transparent and conical, with six or seven flat-sided or slightly swollen whorls and a sharp apex. It bears fine irregular growth lines and faint spiral lines but appears smooth . The oval or ear-shaped aperture is small and has a thickened peristome. The inner lip is reflexed over the base of the last whorl. There is no umbilicus. The colour is horn or tan, often with a broad reddish band on the last whorl.

This small snail lives in Western Europe, primarily on the southern part of the North Sea coasts, in countries and islands including:

• Great Britain
• Ireland
• The Netherlands

This species reproduces sexually. The male has a penis in the middle, or at least close to the middle, of his head. The female has a series of translucent glands the lead to a seminal receptacle, where an egg waits for the semen.^[3]

• Rowson, B., Powell, H., Willing, M., Dobson, M. & Shaw, H. (2021). Freshwater Snails of Britain and Ireland. FSC Publications, Telford, UK
• Maris, T., O. Beauchard, S. Van Damme, E. Van den Bergh, S. Wijnhoven & P. Meire. (2013). Referentiematrices en Ecotoopoppervlaktes Annex bij de Evaluatiemethodiek Schelde-estuarium Studie naar “Ecotoopoppervlaktes en intactness index”. [Reference matrices and Ecotope areas Annex to the Evaluation methodology Scheldt estuary Study on “Ecotope areas and intactness index”. Monitor Taskforce Publication Series, 2013-01. NIOZ: Yerseke. 35 pp.
• Backeljau, T. (1986). Lijst van de recente mariene mollusken van België [List of the recent marine molluscs of Belgium]. Koninklijk Belgisch Instituut voor Natuurwetenschappen: Brussels, Belgium. 106 pp.
• Fortuin, A. W., de Wolf, L. & Borghouts-Biersteker, C. (1981). The population structure of Assiminea grayana, Fleming, 1828 (Gastropoda, Assimineidae), in the south-west Netherlands. Basteria. 45(4-5): 73-78.

• Fleming, J. (1828). A history of British animals, exhibiting the descriptive characters and systematical arrangement of the genera and species of quadrupeds, birds, reptiles, fishes, Mollusca, and Radiata of the United Kingdom; including the indigenous, extirpated, and extinct kinds, together with periodical and occasional visitants. Edinburgh: Bell & Bradfute / London, James Duncan. Retrieved 23 November 2025.
• Bavay, A. (1920). "Un mollusque nouveau de France". Journal de Conchyliologie. 65: 161–162.
• Gofas, S.; Le Renard, J.; Bouchet, P. (2001). "Mollusca. in: Costello, M.J. et al. (eds), European Register of Marine Species: a check-list of the marine species in Europe and a bibliography of guides to their identification" (PDF). Patrimoines Naturels. 50.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• Shin, Cho Rong, Park, Bia, Choi, Eun Hwa and Hwang, Ui Wook. (2024). "A newly recorded species of Assiminea grayana J. Fleming, 1828 (Gastropoda: Assimineidae) from the Korean Peninsula". Korean Journal of Malacology. 40 (2): 59–66.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• van Aartsen, J.J. (2008). "The Assimineidae of the Atlantic-Mediterranean seashores". Basteria. 72 (4 /6): 172–173. Retrieved 23 November 2025.
• Assiminea grayana at Animalbase
• Assiminea grayana Species account and photograph at Mollusc Ireland.

Media related to Assiminea grayana at Wikimedia Commons