Redescription of Philometra pellucida (Jägerskiöld, 1893) (Nematoda: Philometridae) parasitic in the abdominal cavity of the blackspotted puffer Arothron nigropunctatus (Bloch & Schneider) (Teleostei: Tetraodontidae) off Australia and Japan.

The nematode Philometra pellucida (Jägerskiöld, 1893) (Philometridae) is redescribed from female specimens obtained from the abdominal cavity of the marine tetraodontiform fish (blackspotted puffer) Arothron nigropunctatus (Bloch & Schneider) (Tetraodontidae) off Lizard Island, Australia and off Okinawa, Japan. This is just the second record of this parasite since its description 125 years ago. Light and scanning electron microscopical examination of these nematodes revealed some taxonomically important, previously unreported morphological features, such as the number and arrangement of cephalic papillae, presence of the oesophageal cell nucleus and the size of first-stage larvae in the uterus. This new report of P. pellucida infecting A. nigropunctatus off Australia and Japan represents new host and geographical records. A key to the species of Philometra Costa, 1845 parasitising tetraodontiform fishes is provided.