Key to valid species of Halaphanolaimus

1 Number of precloacal supplements 6 or more............................................................... 2

- Number of precloacal supplements below 6................................................................. 3

2 6–7 precloacal supplements, body length 1.4–1.5 mm,.. spicule length 47–52 µm, diameter of labial region 8 µm, a =33–41, b =6.0–6.6, c =10.7–12.7........................................................... H. pellucidus Southern, 1914

- 12–14 precloacal supplements, body length 0.9–1.2 mm, spicule length 68–70 µm, diameter of labial region 6 µm or less, a =21–25.6, b =4.7–5.4, c =9.9–11.0......................................................... H. sergeevae n. sp.

3 Cervical and somatic setae absent......................................................................... 4

- Cervical and somatic setae present........................................................................ 5

4 Spicule length 35 µm, stoma length 8 µm, c ’=4.0–4.5...................................... H. luridus (Timm, 1963)

- Spicule length 16–18 µm, stoma length 14–18 µm, c ’=5.0–8.1.................. H. cangionensis Gagarin & Thanh, 2007

5 Spicule length 27–28 µm, diameter of labial region 5.5–6.0 µm....................... H. rivalis Gagarin & Thanh, 2007

- Spicule length 15–16 µm............................................................................... 6

6 Body length 0.43 mm – 0.52 mm, a =26–35, b =3.8–4.5............................. H. harpaga Boucher & Bovee, 1972

- Body length more than 0.6 mm, a =40–45, b =5.3–6.1............................ H. lorenzeni Boucher & Bovee, 1972