The long-legged flies (Dolichopodidae) of the island of Montserrat in the Lesser Antilles have been surveyed and include 63 species in 27 genera. The following eleven new species are described and illustrated: Amblypsilopus marskeae sp. nov., Medetera iviei sp. nov., Medetera montserratensis sp. nov., Systenus ladonnae sp. nov., Thrypticus mediofuscus sp. nov., Chrysotus antillensis sp. nov., Chrysotus callichromoides sp. nov., Chrysotus interfrons sp. nov., Chrysotus montserratensis sp. nov., Diaphorus robinsoni sp. nov., and Sympycnus montserratensis sp. nov. Six species have only been found on Montserrat (ca. 10% endemicity). Keys are provided to the genera and species on Montserrat, their known distribution summarized, and additional new island records provided for many species. Asyndetus wirthi Robinson is synonymized with A. interruptus (Loew) and Achradocera apicalis (Aldrich) is removed from synonymy with A. barbata (Loew). Diaphorus flavipes Aldrich is transferred to Chrysotus as a new combination. A new replacement name, Chrysotus milvadu nom. nov., is provided for the Nearctic Chrysotus parvulus Van Duzee. Lectotypes are designated for Achradocera apicalis (Aldrich) and Asyndetus fratellus Aldrich. The fauna of Montserrat is summarized and compared with that of Dominica. Collecting methods are compared and threats to the dolichopodid fauna of Montserrat discussed.
Keywords: Biodiversity; Caribbean; Lesser Antilles; West Indies; checklist; inventory; new species.