Key to the known species of the genus Fissicepheus .

1. Co.ag absent........................................................ F. ( Psammocepheus .) amabilis Aoki, 1970

- Co.ag present........................................................................................ 2

2. Ten pairs of notogastral setae............................................................................ 3

- Fourteen pairs of notogastral setae....................................................................... 23

3. Anterior end of lamella conspicuously widened, petal-shaped................................................... 4

- Anterior end of lamella not widened....................................................................... 5

4. Notogastral setae with fine tips......................................... F. ( Fissicepheus .) mitratus Mahunka, 1971

- Notogastral setae dilated......................................................... F. (F.) coronarius Aoki, 1967

5. Developed tubercles present behind prodorsal condyles.............................. F. (F.) thaiensis Mahunka, 2008

- No tubercles present behind prodorsal condyles.............................................................. 6

6. Co.nm present........................................................................................ 7

- Co.nm absent........................................................................................ 18

7. Notogastral setae bifid apically........................................... F. (F.) elegans Balogh et Mahunka, 1967

- Notogastral setae not bifid apically........................................................................ 8

8. Co.nm connected with each other......................................................................... 9

- Co.nm separated from each other........................................................................ 11

9. Spa.l fused to each other to form a brim-like structure..................................... F. (F.) vicinus Aoki, 1986

- Spa.l not fused to each other............................................................................ 10

10. Seta le inserted at tip of lamella........................................................ F. (F.) wangae sp. nov.

- Seta le inserted far from tip of lamella.............................................. F. (F.) combicondylus sp. nov.

11. Apical part of ss with strong spines...................................................................... 12

- Ss with relatively smooth margin........................................................................ 13

12. Notogastral setae strongly barbed in distal third............................................... F. (F.) aokii sp. nov.

- Notogastral setae minutely barbed uniformly........................................ F. (F.) corniculatus Aoki, 2009

13. Spa.l fused to each other to form a brim-like structure........................................................ 14

- Spa.l not fused to each other............................................................................ 16

14. Surface of femora I–IV and trochanters III–IV densely granulated.......................... F. (F.) confragosus sp. nov.

- Surfaces of legs without granules........................................................................ 15

15. Co.pm small, connected by a transverse ridge........................................... F. (F.) gracilis Aoki, 2006

- Co.pm well developed, transverse ridge absent........................................ F. (F.) clavatus (Aoki, 1959)

16. Interlamellar, notogastral and ano-adanal setae dilated in medial part......... F. (F.) striganovae Ermilov et Anichkin, 2014

- Interlamellar, notogastral and ano-adanal setae with fine tips.................................................. 17

17. Notogaster without a chitinous transversal band anterior to seta h 2.................... F. (F.) subclavatus Mahunka, 1971

- Notogaster with a chitinous transversal band anterior to seta h 2............ F. (F.) takenouchiensis Fujikawa et Nishi, 2013

18. All notogastral setae dilated and leaf-like............................................... F. (F.) nakanei Aoki, 1986

- Notogastral setae not leaf-like.......................................................................... 19

19. Co.pm absent........................................................................................ 20

- Co.pm present....................................................................................... 22

20. Rostral apex deeply U-shaped incised........................................... F. (F.) steinmanni Mahunka, 1971

- Rostral apex not excised............................................................................... 21

21. Head of ss with strong spines........................................................ F. (F.) defectus Aoki, 2006

- Ss with a finely roughened head, without spines......................................... F. (F.) haradai Choi, 1986

22. Ss clavate; genital plate with 1or 2 longitudinal striae....................................... F. (F.) mitis Aoki, 1970

- Ss with a rounded head; genital plate without striae...................................... F. (F.) chinensis Wen, 1993

23. Co.pm and co.nm absent....................................................... F. (F.) claviopsis Mahunka, 1971

- Co.pm and co.nm present.............................................................................. 24

24. Seta le inserted at tip of lamella................................................ F. (F.) sitnikovae Sergienko, 1976

- Seta le inserted behind tip of lamella..................................................................... 25

25. Notogastral setae long and strongly curved....................................... F. (F.) curvisetosus Kubota, 2001

- Notogastral setae short and almost straight...................................... F. (F.) ornithorrhynchus Wen, 1993