Cercus

In the stem-species pattern of the Chloropidae family-group the cerci are not fused. In the Chloropidae the cerci are fused posteromedially. In the Acartophthalmidae there is a kind of narrow lip on the outer margin of the cerci, which is neither sclerotised nor covered with setae.
In the Milichiidae the cerci can vary in size. In Desmometopa they are nearly as large as the epandrium in lateral view, while they are very small in Leptometopa and Neophyllomyza among others. Setae can be found mainly on the outer margin, one or two very large ones being apical. The cerci can be sclerotised to a varying extent. However, in species with lightly sclerotised cerci the ventral margin is often more strongly sclerotised. Several Milichiidae show some kind of lip on the outer margin of the cerci, which is neither sclerotised nor covered with setae. In Desmometopa, Litometopa, Phyllomyza, and Stomosis, this lip is particularly strongly developed. In many genera the lip is scarcely or not at all visible.
The lips on the cerci could be an apomorphy for the Milichiidae. In this case the lip was secondarily reduced several times within the family. But the character is difficult to evaluate, because the lip is often narrow or difficult to see. Among these narrow forms in particular, differences between species of the same genus occur. For the exact evaluation of this character, the stem-species pattern of each genus has to be studied first. (ex Brake 2000)