elphidium williamsoni elphidium williamsoni elphidium williamsoni is a species of foraminiferans belonging to the family elphidiidae. elphidium williamsoni is found in abundance around the coasts of the uk, predominantly in the lower end of the coast. elphidium williamsoni scientific classification domain: eukaryota clade: diaphoretickes clade: sar phylum: retaria infraphylum: foraminifera class: globothalamea order: rotaliida family: elphidiinae genus: elphidium species: e. williamsoni binomial name elphidium williamsonihaynes, 1973 synonyms cribroelphidium williamsoni (haynes, 1973) elphidium excavatum subsp. williamsoni haynes, 1973 elphidium longipontis stschedrina, 1962