The illustrious shell of the “Imperial Harp”, with its elegantly ornamentation of numerous ribs, is arguably one of the most fascinating and elegant of all molluscs. Though it is a classic rarity chosen by S. Peter Dance as one of his fifty “Rare Shells” (1969), it was only truly rare before the early 1900s when its provenance was revealed in Mauritius.

Today we know its distribution is indeed a very restricted one in the Mascarene Basin, ranging from Mauritius to Reunion to eastern Madagascar; vast majority of specimens originate from Mauritius, where it is probably best described as locally uncommon. However, as there are legal restrictions to collecting in Mauritius and the fact that high quality specimens are scarce, its price remains high and continues to be one of the most sought-after species in Harpidae.

Like other Harpa species it is a carnivorous and predatory gastropod feeding on small crustaceans, mainly crabs, and it inhabits sandy bottoms of shallow water down to about -15m deep. Typical shell length around 65mm, though the largest specimen known reaches a staggering size of 111mm.

Though it is an unmistakable, instantly recognisable species with a little-varied general form, the width and frequency of ribs vary greatly. This led to a form with widely spaced ribs being described as Harpa laetifica Melvill, 1916, and a form with very dense ribs was given the name Harpa multicostata Sowerby I, 1822; both are now considered to be synonyms.

Another well-known synonym is Harpa imperialis Lamarck, 1822, from which its common name originate. Furthermore, a local form from southeast Madagascar with supposedly stronger-than-usual yellow colouration in the aperture was recently named Harpa costata f. lutea Bozzetti, 2012; but this was described as a form and thus carries no taxonomic validity under the current International Code of Zoological Nomenclature. – Description with thanks from Chong Chen.