Key to species of Marphysa currently accepted as occurring in China (following Liu et al. 2017 and Glasby et al. 2016)

1 Margins of prostomium rounded margins, without sulcus............................. Marphysa sinensis Monro, 1934

- Margins of prostomium rounded, with median sulcus......................................................... 2

2(1) Two types of compound chaetae present, falcigers and spinigers................................................. 3

- Only compound spinigers present......................................................................... 4

3(2) Pectinate chaetae start from chaetiger 3.......................................... Marphysa maxidenticulata n. sp.

- Pectinate chaetae start from chaetiger 193..................................... Marphysa orientalis Treadwell, 1936

4(2) Compound spinigers present along entire body.............................. Marphysa digitibranchia Hoagland, 1921

- Compound spinigers restricted to posterior chaetigers......................................................... 5

5(4) Three types of pectinate chaetae present.................................................................... 6

- Two or four types of pectinate chaetae present............................................................... 7

6(5) Pectinate chaetae from first few chaetigers, branchiae with up to 5 filaments present from chaetigers 29–36.................................................................................................. Marphysa bulla n. sp.

- Pectinate chaetae present from chaetiger 20, branchaie with 2–3 filaments present from chaetigers 16–26.......................................................................... Marphysa tribranchiata Liu, Hutchings & Sun, 2017

7 (4) Two types of pectinate chaetae present from anterior chaetigers, 6–8 branchial filaments per chaetiger............................................................................... Marphysa tripectinata Liu, Hutchings & Sun, 2017

- Four types of pectinate chaetae present from chaetiger 70, 3–5 branchial filaments per chaetiger.................................................................................. Marphysa multipectinata Liu, Hutchings & Sun, 2017