1 Furcal knobs with 2+2 setae............................................................................. 2
- Furcal knobs with 3+3 setae............................................................................ 3
2 AIIIO with 5 guard setae; PAO vesicles divided; Abd. IV without ventral swellings; 5+5 cephalic pso........ P. bashkirica (Khanislamova, 1986); Russia, southern Urals
- AIIIO with 4 guard setae; PAO vesicles simple; Abd. IV with ventral swellings; 3+3 cephalic pso in МN position........ P. pseudopodis sp. nov. ; Russia, European part
3 Head with 3+3 pso.................................................................................... 4
- Head with 2+2 pso.................................................................................... 6
4 Cephalic pso in OR position............................................................................ 5
- Cephalic pso in MN position.................... P. altaica Weiner, Stebaeva & Kaprus’, 2019; Russia, southern Siberia
5 PAO vesicles compound; Abd. III without pso....... P. obesa (Mills, 1934); United States, Iowa, Wisconsin, and Missouri
- PAO vesicles simple or bilobed; lateral pso present on Abd. III............... P. silvestris sp. nov. ; Russia, European part
6 Cephalic pso in MN position..................................... P. ryozoyoshii Weiner & Najt, 2000; North Korea
- Position of cephalic pso different........................................................................ 7
7 Cephalic pso in BA position............................................................................ 8
- Cephalic pso in OR position............................................................................ 9
8 VT with 8(9)+8(9) setae; 2+2 pso on Abd. IV................... P. olga Babenko & Fjellberg, 2016; Russia, North-East
- VT with 7+7 setae; 1+1 pso on Abd. IV..................... P. martynovae (Stebaeva, 1985); Russia, southern Siberia
9 Unguiculus about as long as unguis..................................................................... 10
- Unguiculus shorter than unguis......................................................................... 11
10 Unguis without inner or lateral teeth.............. P. sensillifera (Martynova, 1981); Russia, Far East; northeastern China
- Unguis with clear lateral teeth......................................... P. jirisana Lee & Park, 2021; South Korea
11 PAO with 15–18 vesicles; dorsal sensory setae invisible............................... P. uenoi (Yosii, 1954); Japan
- PAO with 20–25 vesicles; dorsal sensory setae distinct...................................................... 12
12 VT with 5+5 setae; unguiculus as long as 0.8–0.9 of unguis............ P. jiangsuensis Yan, Huang & Chen, 2007; China
- VT with 7+7 setae; unguiculus as long as 0.5–0.6 of unguis........................... P. okafujii (Yosii, 1967); Japan