The Affini Compact has encountered (and domesticated!) far more species than can be listed here! So feel free to come up with new species of sophonts under the vines of the Compact across the many galaxies it's in. The Affini Compact is also ever expanding! (imperialism is bad but we'll ignore that because plants hot) That means that more and more species are being added to the Compact all the time, like terrans.
The Terran Accord on the other hand had only officially discovered the Rinans prior to the Affini Compact. They had on the other hand received long distance communications from the Spectrum Jellies, their other nearby species, but the Accord never realized what the signals were due to language differences.
Cyn - Bovine creatures with three horns—the third upon their noses—who came to a similar conclusion on domestication for the betterment of the universe prior to first contact with the affini. It didn't take them much to realize that the Compact had perfected the art. (Affini Domestication Guide)
Furool - Not usually found in the Milky Way, but known for having a problem with gambling in their pre-domestication era.
Hurkín - Not usually found in the Milky Way, but known for their genetic engineering capabilities prior to domestication.
Hrulians - Highly advanced authoritarian and militaristic civilization encountered by the affini approximately 126,000 years after Human Domestication. One of the few civilizations whose military technology posed any real trouble to the Affini Compact. (For a Better Universe)
Independent Probe Units (Beepers) - Von Neumann probes that out lived their progenitor species. (Divaricated)
Lumari - Feathered reptilians known for their colorful aesthetics.
Mielyu - Fully-aquatic species of sophonts who live among jungles of seaweed and coral. They are sleek creatures with heads like that of a catfish and long tails that end in fins as well as arms sprouting from the sides of their bodies to allow them fine manipulation. Kinda like catfish mermaids! (Flotsam Heart)
Myrmex, a species of ant-like xenos that are known to enjoy chewing on plant matter. (Petals and Vines)
Quinoth - Insectoid a with semi crystalline carapace from a high gravity world. Pretty & durable. Had more advanced biotech than humanity when the affini encountered them around 100 Terran years ago; still lost!
Rinans - Small nocturnal mammalians who were the first xenosophont species encountered by the Accord.
Spectrum Jellies - Jellyfish people, xenophilic, slightly outside of the Terran Accord sphere prior to the affini showing up. Willingly surrendered to the affini. Communicate via bioluminescence. Genetically engineered 12? humanoid forms after receiving a Terran SETI signal but didn't think that the Terrans might not communicate via bioluminescence. Affini upstaged them by being cool shapeshifters. (Abscission)
Tigrasi - A tiger-like species that lean heavily on advanced prosthetics and translator drones to handle fine motor control, on account of their big useless bappy paws and the fact that they moo and growl like a big cat with those huge dumb cute toofs. (Abscission (first referenced); Be My Valentine (named and properly introduced).