A new species of fortuyniid mite, Alismobates keniaensis sp. nov., from the coast of Kenya is described and an assessment of the biogeographic distribution pattern of marine associated ameronothroid mites occurring on African coasts is provided. Alismobates keniaensis sp. nov. represents the first record of the genus Alismobates from Africa and this species can be easily distinguished from its congeners by the position of notogastral seta C₁ on the lenticulus, fifteen pairs of notogastral setae, relatively long interlamellar setae and drop-shaped granular cavities next to acetabula IV. A further intertidal species, the selenoribatid Schusteria melanomerus, was also found on Kenyan shores indicating that this species shows a continuous distribution along the eastern African coast from Kenya to Mozambique. Basically, the subtropical and tropical Fortuyniidae and Selenoribatidae are concentrated along the south-eastern shoreline of Africa whereas the cold-adapted Ameronothridae mainly occur at the south-western tip of the African continent. This distribution pattern coincides with the prevalence of the warm Agulhas current off the east coast and the cold Benguela current off the west coast of southern Africa. In sum thirteen species from three ameronothroid families can be found on this continent, of which eight are endemic to Africa. However, more than half of the whole African coastline has not been investigated so far and therefore present biogeographic knowledge on these mites of this region should be regarded as only preliminary data.