The taxonomic and conservation status of Thyasira gouldi (Philippi, 1844), the northern hatchet shell, in British waters

Thyasira gouldi is shown to have a wider British distribution than previously thought. It is confirmed to range along the west coast of Scotland from Loch Sween in the south to Loch Etive, Loch Eil and "Cape Wrath" in the north. Additionally it is a frequent component of the fauna of Sullom Voe, Shetland and has recently been found on the east coast of Scotland in the Firth of Forth. T. gouldi is not recorded from the open North Sea and appears to be confined to inlets and sea lochs The discrimination of T. gouldi and T. flexuosa is reviewed and the prodissoconch size is considered to be the most reliable character. Variation and growth changes in T. gouldi are illustrated. The conservation status is reviewed but any change is not recommended until there is a greater understanding of the ecology and population genetics.