Fourth planet (of eight) in the system 12 822 Pegasus, a system of eight planets and a single G-class yellow dwarf star. Meridian is a Terra-alpha class planet, most of its surface is covered by oceans, dark green in color, with a single large continental landmass. Meridian was charted by the Pathfinder Ship Pegasus in the Sapphirean Year AS 7300. (Book 1: Meridian )
At the time of its rediscovery, Meridian had been invaded, sort of, by a collective hive-mind insectoid species subsequently identified as the tkelektetl. The aliens did not invade the planet directly, but rather sent out a large, sophisticated space probe that was programmed to seek out worlds with a central intelligence and take it over for their own purpose. Meridian's people were governed by such an artificial intelligence -- the Integrated Planetary Management System -- that made them uniquely vulnerable to an invasion of this type. The aliens seized control of the system and used it to begin transforming the planet into a replica of its own civilization. It gathered all the people into concentrated urban arcologies and then began a gradual process of evolutionary genetic manipulation resulting in each successive generation becoming more insect-like.
The intervention of the Pathfinder Ship Pegasus interrupted the alien efforts to transform the planet by destroying the central intelligence systems of the planet. In the aftermath, many but not all of the transfigured human people died off. They continued to live and evolve side by side with the surviving remnants of the human population.