Guide to the Parasites of Fishes of Canada Part V: Nematoda Author Arai, Hisao P. Author Smith, John W. text Zootaxa 2016 4185 1 1 274 journal article 10.11646/zootaxa.4185.1.1 11620862-ddcf-4c01-b0d9-32867e03d74b 1175-5326 165530 0D054EDD-9CDC-4D16-A8B2-F1EBBDAD6E09 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