The branchiobdellidan species Holtodrilus truncatus (Liang, 1963) is reported for the first time in Korea. The genus Holtodrilus Gelder and Brinkhurst, 1990 is monotypic within the family Xironodrilidae, and the genus and family of this species are also new to the Korean fauna. The branchiobdellidan specimens were collected from the exoskeletons of the freshwater atyid shrimp, Neocaridina sp., sampled from the ‘Andeok Valley’, Jeju-do Province, South Korea. Holtodrilus truncatus is characterized by its terete body form, 7/7 dental formula (with a large medial tooth and three pairs of smaller lateral teeth), and no trunk appendages. In addition, we determined a partial sequence of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene as a DNA barcode marker for H. truncatus. The present study is the first record of the branchiobdellidan occurrence on a non-crayfish host (shrimp) in Korea. To date, seven species (four genera in three families) of branchiobdellidans have been reported in the Korean fauna.
Folmer, O., M. Black, W. Hoeh, R. Lutz and R. Vrijenhoek. 1994. DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates. Molecular Marine Biology and Biotechnology 3: 294-299.
Fujita, Y., T. Kawahara, N. Niwa and S. Shokita. 2010. First record of Holtodrilus truncatus (Liang, 1963) (Annelida, Clitellata: Branchiobdellidae) from the Ryukyu Islands. The Biological Magazine Okinawa 48: 25-33.
Gelder, S. and R. Brinkhurst. 1990. An assessment of the phylogeny of the Branchiobdellida (Annelida: Clitellata), using PAUP. Canadian Journal of Zoology 68: 1318-1326.
Gelder, S.R. 1999. Zoogeography of branchiobdellidans (Annelida) and temnocephalidans (Platyhelminthes) ectosymbiotic on freshwater crustaceans, and their reactions to one another in vitro. Hydrobiologia 406: 21-31.
Gelder, S.R. 2010. Re-description of the Branchiobdellidan Hidejiodrilus koreanus (PIERANTONI, 1912), (Annelida: Clitellata), from the Republic of Korea, and the Designation of a Neotype and Paraneotype Specimens. Acta Zoologica Bulgarica 62: 21-26.
Lee, J.H., T.W. Kim and J.C. Choe. 2009. Commensalism or mutualism: conditional outcomes in a branchiobdellid-crayfish symbiosis. Oecologia 159: 217-224.
Liang, Y.-L. 1963. Studies on the aquatic Oligochaeta of China. I. Descriptions of new naids and branchiobdellids. Acta Zoologica Sinica 15: 560-570.
Liu, S.-C. 1984. Descriptions of two new species of the genus Stephanodrilus from northeast china and notes on St. truncatus Liang from Guangdong Province. Acta Zootaxonomica Sinica 9: 351-355.
Niwa, N., M. Archdale, T. Matsuoka, A. Kawamoto and H. Nishiyama. 2014. Microhabitat distribution and behaviour of Branchiobdellidan Holtodrilus truncatus found on the freshwater shrimp Neocaridina spp. from the Sugo River, Japan. Open Life Sciences 9: 80-85.
Niwa, N. and A. Ohtaka. 2006. Accidental introduction of symbionts with imported freshwater shrimps. In: F. Koike, M.N. Clout, M. Kawamichi, M. De Poorter and K. Iwatsuki (eds.), Assessment and Control of Biological Invasion Risks, Gland, Shoukadoh Book Sellers, Kyoto, Japan and IUCN. pp. 182-186.
Niwa, N., J. Ohtomi, A. Ohtaka and S.R. Gelder. 2005. The first record of the ectosymbiotic branchiobdellidan Holtodrilus truncatus (Annelida, Clitellata) and on the fresh-water shrimp Neocaridina denticulata denticulata (Caridea, Atyidae) in Japan. Fisheries Science 71: 685-687.
Ohtaka, A. 2007. Distribution of exotic branchiobdellidans (Annelida, Clitellata) in Japan. Japanese Journal of Limnology 68: 483-489.
Ohtaka, A. and R.-T. Chen. 2010. New records of a branchiobdellidan and four microdrile oligochaetes (Annelida: Clitellata) from inland waters of Taiwan. Taiwan Journal of Biodiversity 12: 97-110.
Ohtaka, A., S. Gelder, M. Nishino, M. Ikeda, H. Toyama, Y.-D. Cui, X.-B. He, H.-Z. Wang, R.-B. Chen and Z.-Y. Wang. 2012. Distributions of two ectosymbionts, branchiobdellidans (Annelida: Clitellata) and scutariellids (Platyhelminthes: “Turbellaria”: Temnocephalida), on atyid shrimp (Arthropoda: Crustacea) in southeast China. Journal of Natural History 46: 1547-1556.
Subchev, M., L.S. Stanimirova and T. Tomek. 1991. Distribution of branchiobdellidans (Annelida, Clitellata) on the Korean Peninsula. Acta Zoologica Bulgarica 41: 12-17.
Tanaka, K., K. Wada and K. Hamasaki. 2016. Distribution of Holtodrilus truncatus, a Branchiobdellidan Ectosymbiotic on Atyid Shrimps in the Kii Peninsula, Western Japan, with Reference to Salinity Tolerance and Host Preference. Zoological Science 33: 154-161.
Yamaguchi, H. 1934. Studies on Japanese branchiobdellidae with some revisions on the classification. Journal of The Faculty of Science Hokkaido Imperial University Series VI. Zoology 3: 177-219.