The work presents molecular genetic analysis and data on the ecology and distribution of the symbiotic polychaete genus Cheilonereis Benham, 1916 (Polychaeta: Phyllodocida: Nereididae), which is associated with hermit crabs in the southern part of Primorye (mainly in the Peter the Great and Posyet Bays of the Sea of Japan).
Comparison of mtDNA COI gene marker sequences between specimens of the nereidid polychaete genus Cheilonereis from the east coast of Korea and C. cyclurus from British Columbia, Canada, revealed interspecific genetic differences of approximately 17% (p-distance – 0.173). According to our analysis, specimens collected from the Russian coast of the Sea of Japan differ genetically from the C. cyclurus specimen from British Columbia by approximately 14.7% (p-distances – 0.147), while the genetic divergence with the Korean specimens is approximately 1.4% (p-distances – 0.014). Thus, the species from the northeastern Pacific Ocean should be considered a separate species, which was previously described as Cheilonereis shishidoi (Izuka, 1912).
“The calculated intraspecific genetic divergence within the studied population of Cheilonereis shishidoi (n=11) living along the Russian coast of the Sea of Japan is about 1.9% (p-distances – 0.019) and about 0.5% (p-distances – 0.005), respectively, in the Korean population (n=4). These results indicate that the genetic differences between the Russian and Korean populations can be considered as intraspecific,” says the author of the study, an employee of the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, PhD Ivan Marin.
The species described above is not the only species of nereidid polychaetes associated with hermit crabs. Thus, Cheilonereis cyclurus (Harrington, 1897) is known as a commensal of the shallow-water hermit crabs Pagurus aleuticus (Benedict, 1892), P. ochotensis, Pagurus armatus (Dana, 1851), Paguristes turgidus (Stimpson, 1857) and Elassochirus tenuimanus (Dana, 1851) (Decapoda: Paguridae) along the American coast from the Gulf of Alaska to California.
Cheilonereis peristomialis Benham, 1916 is a commensal of the hermit crab Pagurus edwardsii (Dana, 1852) (= Eupagurus edwardsii) from Tasmania and South Australia (Young, 1923).
Neanthes fucata (Savigny, 1822) lives in empty gastropod shells inhabited by the hermit crabs Pagurus prideaux Leach, 1815 and Pagurus bernhardus (Linnaeus, 1758) in the northeastern Atlantic Ocean, the North Sea and the Mediterranean Sea.
The work was published in the journal: Marin I.N. 2024. Cheilonereis shishidoi (Izuka, 1912) is the correct taxonomic name for the nereidid polychaete species associated with hermit crabs along the Russian coast of the Sea of Japan // Invert. Zool. Vol.21. No.4: 495–501.