Cosmocephalus

Mutafchiev, Yasen, Halajian, Ali & Georgiev, Boyko B., 2010, Two new nematode species of the genus Cosmocephalus Molin, 1858 (Spirurida: Acuariidae), with an amended generic diagnosis and an identification key to Cosmocephalus spp., Zootaxa 2349, pp. 1-20 : 18

Key to the species of Cosmocephalus

1a. Anterior loops of cordons reach between one quarter and one third of the length of cordons ......................... C. faridi

1b. Anterior loops of cordons markedly shorter, do not exceed one quarter of the length of cordons.............................. 2

2a. Lateral alae absent ........................................................................................................................................ C. pelecani

2b. Lateral alae present ....................................................................................................................................................... 3

3a. Deirids bicuspid ........................................................................................................................................................... 4

3b. Deirids tricuspid........................................................................................................................................................... 6

4a. Cordons with both descending and ascending arms scalloped ..................................................................................... 5

4b. Cordons with descending arm scalloped, ascending arm not scalloped ...................................................... C. podicipis

5a. Cordons shorter than 450 µm in males and than 550 µm in females, rarely longer; distal end of left spicule with sub- terminal projection ...................................................................................................................................... C. obvelatus

5b. Cordons 450–470 µm long in males and 540–650 µm long in females; tip of left spicule pointed, without projection ................................................................................................................................................................... C. imperialis

6a. Cordons with well-expressed scalloped structure; inner row of plates 38 µm wide in males; left spicule more than 600 µm long .................................................................................................................................................. C. jaenschi

6b. Cordons not scalloped, width 25 in female and 20 in males; left spicule less than 400 µm long .............. C. capellae