Hysterothylacium gibsoni sp. nov. and H. tetrapteri (Bruce et Cannon, 1989) (Nematoda: Ascaridida) from the Chinese marine fishes
AbstractA new species of ascaridoid nematode, Hysterothylacium gibsoni sp. nov., is described based on specimens collected from the intestine of the slender lizardfish Saurida elongata (Temminck et Schlegel) (Aulopiformes: Synodontidae) in the Yellow Sea, China. The new species differs from its congeners by its small body size (12.8–13.2 mm), the absence of cervical alae, a very short intestinal caecum (representing 8.86–9.52% of oesophageal length) and a long ventricular appendix (intestinal caecum to ventricular appendix ratio 1:15.3–20.0), short spicules (0.38–0.41 mm, representing 2.97–3.11% of body length), the number and arrangement of the caudal papillae (25–28 pairs arranged as follows: 18–22 pairs precloacal, 3 pairs paracloacal, and 3–4 pairs postcloacal). In addition, Hysterothylacium tetrapteri (Bruce et Cannon, 1989) is also redescribed based on the material collected from the striped marlin Kajikia audax (Philippi) (Perciformes: Istiophoridae) in the South China Sea.