Hysterothylacium

Arai, Hisao P. & Smith, John W., 2016, Guide to the Parasites of Fishes of Canada Part V: Nematoda, Zootaxa 4185 (1), pp. 1-274 : 137-138

Key to species of Hysterothylacium from marine fishes

1 Deep interlabial grooves present; spicules 2.6–8.7 long, ratio 1: 0.9–1.0; cuticle with enlarged and modified annules on ventral surface of males near cloaca; tail tip usually lacking spines.......................................... H. incurvum

- Interlabial grooves absent.............................................................................. 2

2 Tail tip lacking spines; spicules 1.2–2.6 long, ratio about equal...................................... H. corrugatum

- Tail tip with spines................................................................................... 3

3 Tail tip multispinous; spicules 1.7–2.4 long, ratio variable............................................ H. reliquens

- Tail tip with few spines; spicules 2.0–4.65, ratio equal............................................... H. aduncum