1	Chaeta O of tubercle Fr absent	2
–	Chaeta O of tubercle Fr present	6
2	Tubercle Dl of Th. II–III with 5 (4+s) chaetae (besides of ms)	P. erawan (Thailand)
–	Tubercle Dl of Th. II–III with 4 (3+s) chaetae (besides of ms)	3
3	Tubercle Di of Th. II–III only with 1 chaeta, tubercle Oc on head only with Ocm chaeta	P. selangorica (Malaysia)
–	Tubercle Di of Th. II–III with 2–3 chaetae, tubercle Oc on head with 2–3 chaetae	4
4	Tubercle Di of Th. II–III with 2 chaetae	P. penangensis (Malaysia)
–	Tubercle Di of Th. II–III with 3 chaetae	5
5	Abd. I–III: tubercle De with 5 (4+s) chaetae, tubercle Dl with 3 chaetae; mandible complicated, totally with 16 teeth in two rows	P. apsala (Thailand)
–	Abd. I–III: tubercle De with 4 (3+s) chaetae, tubercle Dl with 2 chaetae; mandible relatively simple, with 5 or 6 teeth in one row	P. kinabaluensis (Malaysia)
6	Tubercle De of Th. II–III with 4 (s+3) chaetae, VT with 3+3 chaetae	P. sabahna (Malaysia)
–	Tubercle De of Th. II–III with 5 (s+4) chaetae, VT with 4(5)+4(5) chaetae	7
7	Tubercle Di, De, DL of Th. I respectively with 2, 2, 1 chaetae	8
–	Tubercle Di, De, DL of Th. I respectively with 1, 2, 1 chaetae	9
8	Tubercle Dl of Th. II–III with 4 (3+s) chaetae, tubercle Dl of Abd. IV with 6 (5+s) chaetae	P. khaochongensis (Thailand)
–	Tubercle Dl of Th. II–III with 5 (4+s) chaetae, tubercle Dl of Abd. IV with 3 (2+s) chaetae	P. paraperfusa (Philippines)
9	Tubercle De and Dl of Abd. V fused, body tricolour	P. orousseti (Philippines)
–	Tubercle De and Dl of Abd. V separate, body red color	10
10	Mandible with 20 teeth	P. palustris (China)
–	Mandible with less than 8 teeth	11
11	Mandible with 6 teeth, tubercle L of Abd. II-III with 6 (5+s) chaetae	P. breviseta (China)
–	Mandible with 7 teeth, tubercle L of Abd. II-III with 4 (3+s) or 7 (6+s) chaetae	12
12	Tubercle Di of Th. II–III with 2 chaetae, tubercle L of Abd. II-III with 4 (3+s) chaetae, mandibular basal tooth much larger than the second tooth	P. perfusa (Indochina)
–	Tubercle Di of Th. II–III with 3 chaetae, tubercle L of Abd. II-III with 7 (6+s) chaetae, mandibular basal tooth slightly larger than the second one	P. tianmuna sp. n.