Key to the Korean species of Elasmostethus

1 Mediotergites of abdominal segments V–VII entirely dark; posterior margin of pygophore with a pair of pigmented denticles (Figs. 41–42)......................................................................................... 2

- Mediotergites of abdominal segments V–VII at least partly pale; posterior margin of pygophore without paired pigmented denticles (a median projection might be present on ventral infolding)................................................ 3

2 Posterolateral angles of segment VII produced slightly beyond posterior margin of pygophore (Fig. 29); pigmented denticles on pygophore (Fig. 41: ld) situated far from submedian setal tufts, almost in middle of the lateral margin; posterior margins of abdominal segment VIII of female enclosing an obtuse angle, weakly protruding posteriad in the middle (Fig. 30)........................................................................................... E. brevis Lindberg, 1934

- Posterolateral angles of segment VII produced far beyond posterior margin of pygophore (Fig. 31); pigmented denticles on pygophore (Fig. 42: ld) situated immediately laterad of submedian setal tufts; posterior margin of abdominal segment VIII of the female slightly emarginate in the middle (Fig. 32)............................... E. interstinctus (Linnaeus, 1758)

3 Mediotergites of abdominal segments V–VII entirely pale; pygophore with setal tuft at middle of ventral margin (Figs. 43, 44); posterior margin of abdominal segment VIII of female convex at two sides, emarginate medially (Figs. 34, 36)........... 4

- Mediotergites of abdominal segments V–VII partly pale; pygophore without setal tufts (Figs. 45, 46); female genital segment with posterior margin forming approximately a single arc, not emarginate medially (Figs. 38, 40)...................... 5

4 Ventral margin of pygophore with a single median setal tuft, its infolding with a long, dorsocaudally directed, sclerotized and pigmented projection (Figs. 44, 47); paramere with bisinuate lateral margin (Fig. 51); posterior margin of abdominal segment VIII of female deeply excised medially........................................... E. yunnanus Hsiao & Liu, 1977

- Ventral margin of pygophore with two (an upper and a lower) submedian pairs of setal tufts, without sclerotized median projection (Fig. 43); paramere with simple, nearly straight lateral margin (Fig. 50); posterior margin abdominal segment VIII of female slightly emarginate medially................................................. E. humeralis Jakovlev, 1883

5 Posterolateral angles of abdominal segment VII more strongly produced, sharp in both sexes (Figs. 37, 38); pronotum with more or less rectangular humeri; pygophore with rounded posterior margin provided with dense setae in ventral view (Fig. 37); paramere with obtuse outer apical angle (Fig. 52)......................................... E. nubilus (Dallas, 1852)

- Posterolateral angles of abdominal segment VII less strongly produced, obtuse in both sexes (Figs. 39, 40); pronotum with obtuse humeri; male genital segment with nearly straight posterior margin provided with sparse setae (Fig. 39); paramere with rounded outer apical angle (Fig. 53)................................................ E. rotundus Yamamoto, 2003