Field collections reveal that Sao Tome is the Afrotropical island with the highest diversity of drosophilid flies (Diptera: Drosophilidae)

The Drosophilid fauna has been less investigated in the Atlantic Afrotropical islands than in the Indian Ocean. Located about 250 km from the continent, the volcanic island of Sao Tome has been colonized mostly by natural means, probably by the wind, since the emergence of the island about 15 million years ago, and presumably also by anthropogenic transportation of invasive and domestic species. To date, 37 different Drosophilid species have been mentioned from Sao Tome. The present work extends this list to 80 species. The genera Zygothrica, Phorticella and Hypselothyrea are newly recorded from the island. Among these 80 species, only 12 are putatively introduced by human activities, suggesting the preponderance of natural arrivals. Compared to other islands, Sao Tome harbours a high diversity of drosophilids. At least 14 species are supposed to be endemic. Future molecular comparisons between the island flies and their continental relatives will probably help to identify other endemic species. The high diversity observed in Sao Tome is certainly due to the large size of the island, and to the presence of vast natural altitudinal forests offering a variety of possible habitats. Further collections are likely to lead to an increase of the species list. From now, Sao Tome island appears as an excellent laboratory for studying the ecology and evolution of the Drosophila model.