I would welcome help with identification of this small acalypterate, which emerged from decaying horse chestnut wood. The most striking features are the shape of the wings, with almost square ends, and the lack of bristles on the frons apart from one front-orbital.
John and Barbara Ismay have helpfully suggested that this fly may belong to the genus Leiomyza. Indeed it does: L. scatophagina. The wings must be deformed! Rob