Syngnathinema californiense n. gen., n. sp. (Nematoda: Dracunculoidea) from the circulatory system of the bay pipefish Syngnathus leptorhynchus in California.

A new dracunculoid nematode Syngnathinema californiense, n. gen., n. sp., is described from gravid female parasites found inside the heart of wild-caught Bay pipefish Syngnathus leptorhynchus; histologically it was recorded from different sites of the host circulatory system (sinus venosus, atrium, and renal and hepatic veins). The new genus is characterized by the structure of the cephalic end (large oral aperture with a narrow peribuccal ring surrounded by 10 papillae in 2 circles, large circular amphids), division of the esophagus into muscular and glandular portions, location of the well-developed vulva posterior to the esophagus, monodelphic female reproductive organs, and the sharply pointed tail. Because males remain unknown, the genus is provisionally assigned to the Daniconematidae.