Flaxian
From Star Trek : Freedom's Wiki
Flaxians are a spacefaring species native to the Alpha or Beta Quadrant they are most often seen as merchants indicating that they have a well developed economic system.
Faxian assassins are known to employ Pheromonic Sensors in their explosives. These devices are capable of detonating only when a specific species gets close enough to trigger the sensor. One such device was used aboard DS9 in an assassination attempt.
The Romulan Tal Shiar is known to employ members of this species in this capacity. There are also indications that thre Cardassian Obsidian Order also make use of their service.