Redescription and genetic characterization of Hysterothylacium thalassini Bruce, 1990 (Nematoda: Anisakidae) from marine fishes in the South China Sea.

Hysterothylacium thalassini Bruce, 1990, was redescribed using light microscopy and, for the first time, scanning electron microscopy based on newly collected specimens from the marine fishes Priacanthus tayenus Richardson and Pricanthus macracanthus Cuvier (Perciformes: Priacanthidae) in the South China Sea. Previously unreported or inaccurately described morphological features of taxonomic significance are described, including the number and morphology of paracloacal and postcloacal papillae, the morphology of the vulva, and the presence of small phasmids in the both sexes. Moreover, specimens of H. thalassini collected from the 2 hosts were characterized by sequencing and analyzing the internal transcribed spacer (ITS) of the ribosomal DNA. The ITS region of H. thalassini was compared with Hysterothylacium spp. in GenBank, and the results seem to support the validity of the incompletely known species.