Planet: name unspecified. This wrinkly-skinned alien species famed as information merchants was known to the Vulcans before humans, at least in the altered but impermanent future during Archer's multiphasic parasite infection--where Yerdrin Koss is first met by Tucker and Reed in the Ceti Alpha system in 2165.

Later, the species is apparently thought to be extinct until the middle 2360s, when Cmdr. Rudy Ransom renewed first contact sometime before 2369. Other natives include Jaglom Shrek, Yranac, Yog, and the destroyer crew who sold the secrets of Galen's DNA puzzle to the Cardassians as a new energy source — in transmissions overheard by the Romulans. They are empathetically sensable, unlike Ferengi, Breen, and Dopterians. Natives use disrupters as sidearms.

During the early crisis in the Demilitarized Zone, Commander Sisko erroneously refers to these traditional information-brokers as the go-betweens for arms deliveries between Cardassia and The Circle on Bajor some months before; he meant the Kressari. Not surprisingly, at the time his tailor shop is bombed Garak owed money to a Yridian. Constable Odo later took a Yridian smuggler into custody and confiscated a bottle of an unspecified beverage from him as evidence.