Key to species of Plonaphacarus reported from China

1 Anterodorsal part of notogaster protrudent, covering posterior part of prodorsum...................................2

- Anterodorsal part of notogaster normal, not covering posterior part of prodorsum................................... 4

2 Frontal part of notogaster not concave in dorsal view; setae c1 not much more longer than other notogastral setae......... 3

- Frontal part of notogaster concave in dorsal view; setae c1 much more longer than other notogastral setae. P. concavus sp. nov.

3 Most notogastral setae short and bacilliform; prodorsum without lateral carina and posterior furrow... P. hainanensis sp. nov.

- Most notogastral setae long and setiform; prodorsum with lateral carinae and posterior furrows........ P. protrusus sp. nov.

4 Prodorsum with four dorsal carinae....................................................................... 5

- Prodorsum with less than four dorsal carinae................................................................ 6

5 Sensilli long with narrow pedicel and fusiform head; lateral carinae long.......................... P. scrupeus Niedbała

- Sensilli short with narrow pedicel and round head; lateral carinae absent........................... P. rotundus sp. nov.

6 Prodorsum without dorsal carina.......................................................................... 7

- Prodorsum with dorsal carinae............................................................................ 8

7 Lateral carinae of prodorsum long, extending beyond sinus; sensilli long; rostral setae semi-erect.......... P. kugohi (Aoki)

- Lateral carinae of prodorsum short, not beyond sinus; sensilli short; rostral setae procumbent......... P. foveolatus sp. nov.

8 Prodorsum with two low dorsal carinae.................................................................... 9

- Prodorsum with one very strong crown-like crista............................................. P. cristatus sp. nov.

9 Prodorsum with two dorsal carinae; exobothridial setae vestigial............................... P. lanceolatus sp. nov.

- Prodorsum without dorsal carina; exobothridial setae not vestigial.............................. P. bicarinatus sp. nov.