“Cirriformia tentaculata” is considered to be distributed throughout Japanese waters and is used as an indicator species of organic pollution in coastal regions. However, previous studies indicated that “C. tentaculata” from Japan contained cryptic or sibling species. In order to solve this taxonomic problem, we collected specimens of Cirriformia Hartman, 1936 from throughout Japan and conducted taxonomic analyses. Molecular phylogenetic analyses showed that the Cirriformia worms collected could be divided into twelve phylogroups. We conducted detailed morphological analyses of each phylogroup and found morphological differences between each. Ten species were considered new to science, and the remaining two had the morphology according to the original description of C. tentaculata (Montagu, 1808). Physio-chemical characteristics of their habitats were not identical between each species, which suggested that the so-called “C. tentaculata” in Japanese waters is not adequate as a pollutant indicator.

A new species of the genus Nesometra Virgili, Poliseno, Fujita, Pratama, Fernández-Silva, and Reimer, 2023 is described based on the specimens collected from the Amami Islands and Ogasawara Islands, Japan and Cunningham Island, Australia. Nesometra integra n. sp. is distinguished from its single congener, N. sesokonis (Obuchi, Kogo, and Fujita, 2009), by having complete proximal pinnulation and cirri with reduced medial constriction on its distal part.

Acanthocephalans in the polymorphid genus Bolbosoma Porta, 1908 utilize marine mammals and seabirds as the definitive host, and marine fish as the paratenic host. As in many other groups of acanthocephalans, morphology-based species identification at the cystacanth stage of Bolbosoma is challenging; at present, DNA barcoding is the most reliable approach for larval identification. However, sequence data currently available for Bolbosoma are scarce. In this study, we report the morphology and DNA sequence information (cytochrome c oxidase subunit I and 18S rRNA genes) of Bolbosoma cystacanths from six marine fish species collected in Japan.