Santa Clara-based Palo Alto Networks, a developer of cybersecurity software, said today that it has acquired stealthy security company Morta Networks. Financial terms of the buy were not disclosed. Palo Alto Networks said the acquisition will help improve its threat detection and prevention capabilities. Morta Security was headed by Raj Shah. Morta was backed by Andreessen Horowitz, Greylock Partners, Norwest Venture Partners, and Data Collective.