Fortuyniidae

Biogeography of Fortuyniidae

Schuster (1983, 1989) already supposed a transoceanic distribution of the family Fortuyniidae and several years later his assumption was finally confirmed when F. atlantica from the coasts of Bermuda was officially described (Krisper & Schuster 2008). Adding this last Atlantic record to the other known occurrences on coasts of the Indian and Pacific Ocean (Schuster 1989; Bayartogtokh et al. 2009), the diverse genus Fortuynia now exhibits a worldwide pan- and subtropic distribution. (Figure 21)

The less species rich genus Alismobates and the monotypic Circellobates, on the other hand, were found only in a very limited geographic range of the East China Sea, with records of A. rotundus and C. venustus from Hong Kong (Luxton 1992) and A. reticulatus from Hong Kong (Luxton 1992) and the Japanese Ryukyu Islands (Karasawa & Hiji 2004; Karasawa & Aoki 2005). The present discovery of a third Alismobates species on the shores of the Atlantic archipelago of Bermuda expands the geographic distribution of this genus enormously but leaves a large gap in the eastern part of the Pacific Ocean. Quite possibly further islands of the Pacific region, the Pacific as well as the Atlantic coastline of Central America and several Caribbean Islands may have been successfully colonized by this taxon but insufficient sampling within these areas may be responsible for the apparently discontinuous distribution pattern.

At present the new species A. inexpectatus was only recorded from the archipelago of Bermuda, but here it can be found at many localities along the coastline (Figure 22) inhabiting predominantly mats of the alga Bostrychia tenella growing on rocks in the littoral zone.

Although this species, as well as F. atlantica, may be restricted to Bermuda, their endemic status should only be regarded as provisional until the intertidal mite fauna of Central American coasts and the Caribbean Sea are investigated in a more comprehensive way and further distributions of these species can be definitely excluded.

(A sampling excursion to some of these areas will be performed by one of the authors in the near future and is supposed to give further insights into the distribution of these taxa)