Genus Merodon Meigen, 1803

Diagnosis of the Merodon aureus lineage

Mid coxa with long pile posteriorly (Fig. 2A); anterior anepisternum below postpronotum with many long pile (Fig. 2B); species with stocky abdomen (Fig. 2C); lateral sclerites of the aedeagus very small or absent (Fig. 3A: marked with arrow).

Diagnosis of the Merodon bombiformis group

Pedicel elongated, approximately as long as basoflagellomere (Fig. 4); abdomen broad (Fig. 5); metafemur with less serrated apicoventral triangular lamina, usually only the apical dens is distinct (Fig. 6); metatrochanter of males smooth, without calcar (Fig. 6); male genitalia with posterior surstyle lobe usually bent (as on Fig. 7A, D: pl), and hypandrium narrowed medially (as on Fig. 7C: marked with arrow); distribution: Afrotropical Region (Fig. 1).

The Merodon bombiformis group and M. funestus (Fabricius, 1794) differ from other species and groups among the aureus lineage by an elongated pedicel, approximately as long or even longer than basoflagellomere (Fig. 4) and small lateral sclerite of the aedeagus (as on Fig. 3B, D: s) (absent in other species and groups of the aureus lineage, on Fig. 3A: marked with arrow). Morphologically, the M. bombiformis group can be distinguished from M. funestus by the absence of a calcar on metatrochanter in males (present in M. funestus, on Fig. 8A), less dentate apicoventral triangular lamina on the metafemur, but usually with a distinct apical dens (Fig. 8B) (clearly dentate in M. funestus, on Fig. 8A) and by the shape of the posterior lobe of the surstylus: tip rounded in bombiformis group (as on Fig. 13A, D: pl), but tapering in M. funestus (Fig. 19A: pl).