Genus Dioctria Meigen

Dioctria Meigen, 1803: 270 . Type species: Asilus oelandicus Linnaeus, 1758 .

Species of the genus Dioctria are characterized by their relatively small size (7–20 mm.), comparatively slen- der, sometimes clavate abdomen (Hull, 1962), and long antenna (longer than the height of the eye, situated high near the vertex of the head, with a “spoon-shaped” apical segment). The South Korean species are externally similar in appearance, and each species with a wide range of interspecific variation in characters (wing pigmentation, abdominal markings and hair color). The male’s epandria are undivided and our four South Korean species all share medially grooved hypandria (Fig. 12) and stout, truncated aedeagi with 2 slender endoaedeagi (Figs 15, 16). The gonopods with their 3 lobed processes are unique within species and are useful characters for determination. The female genitalia lack spines on the short terminal segment, and are externally generalized and indistinct between species. Hence, they are not illustrated in this study. The following key covers the South Korean species of Dioctria only, and does not apply to other areas.