A new Middle Eocene Baltic amber Exechiini (Diptera: Mycetophilidae) supports the likely rapid radiation of the tribe

Here, we describe a Brachypeza sg. Ristocordyla sp. undetermined from the Eocene Baltic amber, as the first fossil representative of its subgenus, otherwise known from one extant Palaearctic species. We avoid naming it because it is based on a female specimen, hardly comparable to the extant species and to future fossils from the Baltic amber, because the species differences are mainly based on the male genitalia. As other recently described amber species, the new fossil supports a likely rapid radiation of the tribe Exechiini followed by an evolutionary stasis at the genus level.