KEY TO EXTINCT SPECIES OF PALAEOMEDETERUS (MALES)
Incompletely described Palaeomedeterus tertiarius is not included in this key. The characters of the antenna and genitalia are crucial for the species identification.
| 1. Arista-like stylus apical or strictly subapical | 2 | |
| - Arista-like stylus dorsal, at most inserted in small notch of postpedicel | 5 | |
| 2. Postpedicel reniform, distinctly wider than long | 3 | |
| - Postpedicel longer than wide, with one or two drawn-out apices 4 | ||
| 3. Arista-like stylus less than 3 times longer than antennomeres combined (Meunier, 1908: figure 70); hypopygium is “salient”; body length 1.75-2.25 mm; wing length 1.75-2 mm | ||
| P. lentus | ||
| - Arista-like stylus nearly 5 times longer than antennomeres combined (Figure 3B); hypopygium rather small (about 0.6 mm); body length 3.8 mm; wing length 3.1 mm | ||
| P. sublentus sp. nov. | ||
| 4. Arista-like stylus apical, inserted in deep slit of postpedicel (Meunier, 1908: figure 81; Grichanov and Negrobov, 2018: figure 3); body length 2-2.25 mm; wing length 1.9-2 mm | ||
| P. bifurcatus | ||
| - Arista-like stylus strictly subapical; postpedicel with one drawn-out (male; Figure 1B) or angular (female; Figure 1F) apex; body length 1.7 mm; wing length 1.7 mm | ||
| P. manukyani sp. nov. | ||
| 5. First two segments of hind tarsus subequal in length (Meunier, 1908: figure 61; Grimaldi and Cumming, 1999: Pl. 5d); body length 3-3.5 mm; wing length 2-2.7 mm | ||
| P. horridus | ||
| - Hind basitarsus distinctly shorter than next segment | 6 | |
| 6. Postpedicel sub-reniform, with pointed apex (Meunier, 1908: figure 59); body and wing length 1 mm (male) | ||
| P. praeconcinnus | ||
| - Postpedicel sub-triangular or conoid; if postpedicel sub-reniform, then body longer, 1.5-3 mm long | 7 | |
| 7. Cercus with several long cilia at apex; surstylus lanceolate; phallus long and cylindrical; body length 2 mm; wing length 1.5 mm (Meunier, 1908: 54) | ||
| P. languidus | ||
| - Another combination of characters; cercus with short hairs at apex | 8 | |
| 8. Cercus stalk-like, much shorter than surstylus; surstylus narrow, straight almost to apex (Meunier, 1908: figure 65); body length 3 mm; wing length 2.25-2.5 mm | ||
| P. hirsutus | ||
| - Cercus about as long as surstylus | 9 | |
| 9. Cercus rounded-ovate, flat, slightly longer than wide, with long ventral and dorsal marginal setae, with short hairs at apex (Figure 2D); body length 2.4 mm; wing length 2.2 mm | ||
| P. subignavus sp. nov. | ||
| - Cercus much longer than wide, with short setae | 10 | |
| 10. Cercus swollen at base, narrow distally, with flattened and slightly enlarged apex (Meunier, 1908: figure 80; Grichanov and Negrobov, 2018: figure 15); postgonite projected, rhomboid, nearly half as long as cercus; body length 1.5-1.75 mm; wing length 1-1.65 mm | ||
| P. lassatus | ||
| - Cercus ribbon-like, with rounded apex (Meunier, 1908: figure 80; Grichanov and Negrobov, 2018: figure 20); postgonite strongly projected, with hooked pointed lobes, slightly longer than cercus; body length 2.5-3 mm; wing length 2-2.3 mm | ||
| P. ignavus | ||
