In 1975, a report appeared that heralded the discovery of a new virus that was isolated from Ornithodoros capensis ticks collected from abandoned nests of brown pelicans (Pelecanus occidentalis) on coastal islands off southern Texas. Tests on this novel virus, designated Aransas Bay Virus, revealed a relationship with Upolu Virus, known only from Australia.
It was not immediately clear in which family of viruses Aransas Bay Virus should reside. In the end both Upolu Virus and Aransas Bay Virus were tentatively placed in the family Bunyaviridae as two species not assigned to one of the genera of this family.
Thogoto and Dhori viruses.
One possible reason for the extensive distribution of viruses associated with Ornithodoros capensis ticks is the fact that many of its primary hosts, such as terns migrate over vast distances. Also, the warmer climate in the area where Ornithodoros capensis ticks would be deposited by migrating birds would tend to favour tick survival.
I expect more unknown viruses belonging to the family Orthomyxoviridae will be discovered in the near future.
 Yunker et al: Aransas Bay Virus, A New Arbovirus of the Upulo Serogroup from Ornithodorod Capesis (Acari: Argasidae) in Coastal Texas in Journal of Medical Enthomology - 1979
 Briese et al: Upolu virus and Aransas Bay virus, two presumptive bunyaviruses, are novel members of the family Orthomyxoviridae in Journal of Virology - 2014
[3[ Arctic and Tropical Arboviruses: Edited by Edouard Kurstak - 1979