Key to species of Parastenhelia Thompson & Scott, 1903

1. P4 enp-1 without inner seta, enp-3 with three spines/setae (no inner setae); P2 endopod ♂ with armature formula 0.121............................................................................. P. oligochaeta Wells & Rao, 1987 .

– P4 enp-1 with inner seta, enp-3 with five spines/setae (two inner setae); P2 endopod ♂ with armature formula 1.221.......2.

2. Antennule ♀ 8-segmented; P3–P4 exp-1 without inner seta; P5 exopod ♂ 2-segmented.......... P. willemvervoorti sp. nov.

– Antennule ♀ 9-segmented 1; P3–P4 exp-1 with inner seta 2; P5 exopod ♂ 1- or 3-segmented..........................3.

3. P1 enp-1 about six times length of enp-2; P5 exopod ♀ with straight or slightly convex inner margin............................................................................................ P. similis Thompson & Scott, 1903 .

– P1 enp-1 at least seven times length of enp-2; P5 exopod ♀ with slightly concave inner margin........................4.

4. P5 exopod ♀ about three times as long as maximum width; P5 exopod ♂ 3-segmented.. P. hornelli Thompson & Scott, 1903 .

– P5 exopod ♀ about as 2.3 times as long as maximum width; P5 exopod ♂ 1-segmented... P. hornelli sensu Apostolov (1973) .