Philodina

Song, Min Ok & Lee, Chang-Ho, 2017, A new and five rare bdelloids from Korea, Zootaxa 4242 (3), pp. 529-547 : 534-535

Key to the species of genus Philodina

1. Cerebral eyes absent.................................................................................. 2

- Cerebral eyes present................................................................................ 10

2. Dorsal toe pair always extended............................................................... P. duplicalcar

- Dorsal toe pair not always extended..................................................................... 3

3. Two pairs of spurs............................................................................. P. scabra

- One pair of spurs.................................................................................... 4

4. First foot pseudosegment with two small projections................................................... P. childi

- First food pseudosegment without any projections.......................................................... 5

5. Dental formula 4/4–5/5........................................................................ P. grandis

- Dental formula 2/2–3/3............................................................................... 6

6. Interspace between spurs narrower than spur base width..................................................... 7

- Interspace between spurs much wider than spur base width................................................... 8

7. Sulcus as wide as trochal disc width............................................................... P. rapida

- Sulcus much narrower than trochal disc width........................................................ P. plena

8. Interspace between spurs 2.5–3 times as wide as spur base width......................................... P. vorax

- Interspace between spurs much wider than 4 times of spur base width........................................... 9

9. Disc retractor V-shaped or bilobed medially........................................................ P. proterva

- Disc retractor slightly convex and trilobed medially............................................. P. koreana n. sp.

10. Trunk highly granulated; rostrum with collar-like protuberances proximoventrally; first foot pseudosegment with transverse ridge dorsally......................................................................... P. rugosa coriacea

- Trunk smooth...................................................................................... 11

11. Dorsal toe pair always extended a little or fully; upper lip concave medially....................... P. acuticornis odiosa

- Dorsal toe pair otherwise............................................................................. 12

12. Upper lip bilobed; spurs thumb-shaped and with small knob or sharp points at ends........................ P. flaviceps

- Upper lip arched and low; spurs conical, thin, long and curved outward.................................. P. roseola