Paramonohystera, Steiner, 1916

Zhai, Hongxiu, Geng, Chunxiao & Sun, Jun, 2022, Two new species of Xyalidae (Nematoda: Monhysterida) from intertidal zone of the Bohai Sea, China, Zootaxa 5222 (2), pp. 133-144 : 138-139

Updated key for valid species of Paramonohystera (based on Yu & Xu, 2015)

1. Spicules equal or shorter than 40 µm long (s′<2.1)........................................................... 2

- Spicules more than 50 µm long (s′>2.1).................................................................... 3

2. a=36–46, cervical setae absent, spicules 26–27 µm long............................................ P. brevicaudata

- a=20–22, cervical setae 13–15µm long, spicules 38–40 µm long......................................... P. biforma

3. Spicules shorter than 60µm long......................................................................... 4

- Spicules more than 60µm long........................................................................... 6

4. a=21.9, c′=7.2............................................................................ P. parabutschlii

- a>50, c′=7–15 ........................................................................................ 5

5. Tail conico-cylindrical, c′<12, spicules present dilation distally......................................... P. riemanni

- Tail filiform, c′>14, spicules do not present dilation distally..................................... P. gracilis sp. nov.

6. Spicules shorter than 100µm long........................................................................ 7 - Spicules more than 100µm long......................................................................... 11

7. Cephalic setae segmented, s′=2.8................................................................. P. concinna

- Cephalic setae not segmented............................................................................ 8

8. Head diameter smaller than 10 µm long, s′=2.1........................................................ P. zizichi

- Head diameter more than 10 µm long, s′=2.7–4.4............................................................ 9

9. Head diameter 27–35 µm long, s′=2.7........................................................... P. weihaiensis

- Head diameter smaller than 20 µm long.................................................................. 10

10. 12 cephalic setae, s′=4.0–4.4...................................................................... P. sinica

- 10 cephalic setae, s′=3.4......................................................................... P. levicula

11. 12 cephalic setae, s′<3................................................................................ 12

- 10 cephalic setae, s′>3................................................................................ 14

12. Head diameter 9–12 µm, spicules 105–113 µm long................................................... P. halerba

- Head diameter more than 30 µm long.................................................................... 13

13. Spicules 113 µm long, gubernaculum with distal hooks.............................................. P. buetschlii

- Spicules 167 µm long, gubernaculum without distal hooks............................................... P. pilosa

14. Head diameter more than 24 µm long, s′<4................................................................ 15

- Head diameter smaller than 20 µm long, s′>5.............................................................. 16

15. Spicules more than 140 µm long, precloacal supplements present................................... P. eurycephalus

- Spicules shorter than 130 µm long, precloacal supplements absent....................................... P. proteus

16. Precloacal supplements present, spicules 108–116 µm long............................................. P. geraerti

- Precloacal supplements absent, spicules more than 190 µm long.................................... P. megacephala