x1 is an elephant shrew/jumping shrew/sengi (member of Afrotherian mammal order: Macroscelidea) of subtaxon/type/genus/species/variety/breed x2
Does not include shrews, nor rabbits/pikas. Rodents (including rats and mice) are in a completely different order of mammals (although they belong to the same infraclass) and therefore cannot be appropriately referred to by this word. See also: carfu, ratcu, smacu, ractu.