Key to species of Folsomotoma

1 1+1 eyes............................................................................................. 6

- more than 1+1 eyes.................................................................................... 2

2 2+2 eyes............................................................................................. 3

- more than 2+2 eyes.................................................................................... 4

3 Corpus of retinacle with 1 long stout seta; PAO twice as long as broad; AOIII consisting of 2 sensory rods behind cuticle fold................................................................................. F. minuta (Salmon 1949)

- Corpus of retinacle with 2 long curved setae; PAO three times as long as broad; AOIII consisting of 2 sensory rods fully exposed........................................................................ F. anomala (Salmon 1948)

4 3+3 eyes..................................................................... F. bioculata (Womersley 1906)

- 4+4 eyes............................................................................................. 5

5 manubrium with 2+2 ampoule setae; ventrally with 30 setae; Abd. III with 1 dorsal accp seta; Abd IV with 2 accp setae and 1 as seta..................................................................... F. kerguelensis (Enderlein 1903)

- manubrium with 3+3 spine–like setae; ventrally with 40 setae; Abd III with 1 lateral accp seta; Abd IV with 3 accp setae................................................................................. F. octooculata (Willem 1901)

6 length of body> 1.4 mm; corpus of retinacle with 8–12 setae; manubrium with 2+2 ampoule setae..................... 7

- length of body <1.4 mm; corpus of retinacle with 5–7 setae; manubrium with 1+1 ampoule setae...................... 8

7 Abd. IV with 3+3 accp setae, 1+1 as, 1+1 al.......................................... F. boerneri (Enderlein 1903)

- Abd. IV with 3+3 accp setae, without as and al setae...................................... F. subflava (Salmon 1949)

8 Body chaetotaxy plurichaetose; posterior edge of Abd. IV with three ordinary setae between the dorsal internal accp setae............................................................................. F. marionensis (Deharveng 1981)

- Body chaetotaxy paurochaetose; posterior edge of Abd. IV with one ordinary setae between the dorsal internal accp setae.................................................................................. F. punctata (Wahlgren 1939)