Listen to the salarian talking at the Apartments of the Presidium Commons, Citadel. He is standing outside of Apartment 90, discussing how the krogan would benefit if they had the currently extinct kakliosaurs to aid them in battle.
The Argos Rho cluster only becomes available after completing the Priority: Geth Dreadnought mission. Scan the planet Intai'sei in the Phoenix system of the Argos Rho cluster. After gaining the artifact, speak to the salarian War Strategist, who will be standing outside the apartment again.