Sphere Terra

Shortly after Terrans began visiting other star systems, Terran scientists introduced a new rank to the taxonomic system above that of kingdom: Sphere (from 'biosphere'), which indicated the world where the kingdom evolved. I.e., if an organism evolved on Earth, it would belong to Sphere Terra; if it evolved on Vland, it would belong to Sphere Vland; if it evolved on Terra and was transported to Vland 300,000 years ago, it would belong to Sphere Terra; and so on. In the decades and centuries after achieving jump travel, Terran scientists would note that Sphere Terra, often called Terragens, had been widely distributed (to 'over a hundred worlds' by the Ancients and many more by the Vilani).