Key to species of the genus Neodiplopeltula gen. nov. (see Table 6 for additional diagnostic characters)

1. Refractive periamphideal plates absent ............... N. intermedia (Gerlach, 1954) gen. et comb. nov.

– Refractive periamphideal plates present ........................................................................................... 2

2. Refractive periamphideal plates connect on dorsal and ventral body sides ..................................... 3

– Refractive periamphideal plates do not connect ............................................................................... 4

3. Oral opening subdorsal; amphid 32–44 µm long ........ N. onusta (Wieser, 1956) gen. et comb. nov.

– Oral opening terminal; amphid 16–17 µm long ................................................................................. ................. N. obesa (Nguyen Vu Thahn, Nguyen Thahn Hien & Gagarin, 2012) gen. et comb. nov.

4. Oral opening terminal ................................................... N. indica (Gerlach 1962) gen. et comb. nov.

– Oral opening subdorsal ..................................................................................................................... 5

5. Oral opening at level with or posterior to cephalic setae bases, 6–16 µm from anterior end ............. ................................................................................ N. bathmanni (Jensen, 1991) gen. et comb. nov.

– Oral opening anterior to cephalic setae bases, 1–3 µm from anterior end ....................................... 6

6. Refractive periamphideal plates with incised margins; cephalic setae more than 8 µm long ............ .................................................................................... N. incisa (Southern, 1914) gen. et comb. nov.

– Refractive periamphideal plates oval in shape; cephalic setae less than 8 µm long ........................... .................................................................................... N. barentsi (Steiner, 1916) gen. et comb. nov.