Revision of Hypermastus Pilsbry, 1899 and Turveria Berry, 1956 (Gastropoda: Prosobranchia: Eulimidae), two genera parasitic on sand dollars
Nine new eulimid gastropods belonging to the genera Hypermastus Pilsbry, 1899 and Turveria Berry, 1956 are described. Fifteen more eulimids, previously mainly classified in Eulima Risso, 1826 and without known hosts are transfered to Hypermastus based on shell characters. The species with known hosts are parasitic exclusively on clypeasteroid sea urchins (sand dollars) and parasitise the hosts by penetrating the test with their proboscis and ingesting fluid from the vascular system or the gonads of the host. The snails live on their hosts for periods of a few days and dwell in the sediment most of the time.