Abstract

Black fly adults are minute insects with marked structural homogeneity. This is problematic for the study of fossils, wherein only external structural characters are available for study, thus impeding taxonomic studies and phyloge- netic inference. This paper provides a template for future paleontological research on small, structurally homogene- ous, organisms such as black flies, by using cutting-edge tools including large-scale digital microscopy, 3D images derived from micro-CT scanning and geometric morphometrics. These tools reveal difficult-to-observe structures and provide a more objective means for the analysis of character states. We used this approach to study ‘giant’ black flies preserved in Baltic amber of Eocene age. We describe, for the first time, a male plus five additional female specimens of giant black flies from Baltic amber. We discuss the relationships of these fossil flies to each other and to extant (i.e. North American) members of the genus Ectemnia. The male and all females in this study, except Ectemnia lithuanica Yankovsky & Bernotiene, 2005, are confirmed as morphologically consistent with Ectemnia. We further speculate about possible host preferences, way of life and propose best practices for future taxonomic studies on amber fossils.