Key to all species examined of the mutabilis group

1. Palpus dark brown, sexually dimorphic (large, with 2, 3 thin setae in female; slender, with 1 row of 5–7 setae in male) (Figs 2A, 2B, 5 A); proclinate orbital seta (Orb1) close to ocellar triangle (Figs 2A, 2B, 5 A); cercus with 10 long setae near posterior margin (Fig. 5 B, 6–11A)................................................................ mutabilis group...2

- Palpus yellow to brownish, slender in male and female; proclinate orbital seta not close to ocellar triangle; cercus with numer- ous, long or short setae............................................................ other Leucophenga species

2. Wing brown along anterodistal portion, with brown longitudinal stripe from bm-cu vein to r-m vein (Fig. 2 C, 2D)........ 3

- Wing hyaline....................................................................................... 4

3. Abdominal tergites brown to black (Fig. 4 M); scutellum brown (Fig. 3 E); pleura yellow, with brown patches (Fig. 3 F)............................................................................................... L. striatipennis

- Abdominal tergites nearly black (Fig. 3 M, 3N); scutellum yellow, yellowish along margin (Fig. 3 G); pleura yellowish (Fig. 3 H)..................................................................................... L. taiwanensis

4. Mesonotum yellow, with 3 brown longitudinal stripes medially and sublaterally (Fig. 2 I); pleura yellow, with multiple, dark brown to black patches (Fig. 2 J)............................................................. L. magnipalpis

- Mesonotum lacking brown longitudinal stripes; pleura lacking dark brown to black patches........................... 5

5. Mesonotum brownish yellow, brown before scutellum (Fig. 2 E); abdominal tergites usually black (Fig. 4 A, 4M); aedeagus slender, with pubescence apically (Fig. 5 C)......................................................... L. angusta

- Mesonotum nearly yellow; abdominal tergites yellow, with brown patterns; aedeagus with pubescence on distal 1/3....... 6

6. Second abdominal tergite entirely yellow (Fig. 4 D, 4E)................................................ L. bellula

- Second abdominal tergite with brown to black patch medially (Fig. 4 J–L)........................................ 7

7. Scutellum brown along basal margin, brownish yellow medially, pale along distal margin (Fig. 3 A); pleura yellow, with brown patches above (Fig. 3 B)..................................................................... L. nigripalpis

- Scutellum yellow, with brown margin (Fig. 3 C); pleura nearly yellow (Fig. 3 D)........................... L. orientalis