Discovery of Two New European Tree Trunk-Dwelling Medetera Species (Diptera: Dolichopodidae)

Two new European species in Medetera (Diptera: Dolichopodidae) are described here. Medetera demirae sp. nov.—named after the Flemish minister for Justice and Enforcement, Environment, Energy and Tourism (2019–2024)—has been discovered at three localities in the eastern province of Limburg (Flanders, Belgium) and is thus far only known from this area. It can be easily recognized by a dentate hypandrium and phallus, a unique character not found in any other known Medetera species. M. nigrohalteralis sp. nov. had long been regarded as Medetera takagii Negrobov, 1970 by European dolichopodid workers but ultimately proved to represent a separate species. This species seems widespread in northwestern and central Europe. Morphologically, it is very similar to M. takagii and M. tristis (Zetterstedt, 1838) and shares an infuscate halter with both species. It differs from both by the shape of its hypandrium and surstylus. M. demirae sp. nov., large numbers of M. nigrohalteralis sp. nov., and other rarely seen Medetera species were collected in Belgium using a new type of tree trunk eclector. A widespread application of this trap might considerably change our view on the occurrence and rarity of tree trunk-dwelling invertebrates.