An agent pathogenic for laboratory albino Swiss mice was isolated from a pool of Haemaphysalis punctata ticks collected from cattle on a farm located in Alcácer do Sal county, southern Portugal. The isolated virus was shown to be distinct from but serologically related to virus members of the Bhanja antigenic group. This new virus in the family Bunyaviridae was named Palma for the farm where ticks have been collected for several studies.