Taxonomic revision of genus Loxoconcha in Japan and Vietnam and its origin
Author affiliations
DOI:
https://doi.org/10.15625/1859-3097/20770Keywords:
Taxonomy, Loxoconcha, Bonnyannella, origin, SagmatocythereAbstract
In preceding the study, 30 species of the genus Loxoconcha, which were collected on reef slopes, reef flats, tidal beaches, and river mouths in Japan and Vietnam from 2012 to 2015, are reviewed taxonomically. Based on carapace characteristics, such as hinge, fulcral point, muscle scars, and frontal scars, the results show that 27 species still prove to be the genus Loxoconcha. However, two species are assigned to Bonnyannella and one to Sagmatocythere and re-described. In addition, this research also initially reveals the origin and distribution in the Atlantic Ocean of the genus Loxoconcha which is considered as one of the most diversified recent genera in marine ostracods. Fossil records of Loxoconcha species worldwide show that the origination of the genus Loxoconcha may be in Indo-West Pacific Region and by the Late Oligocene (possibly the Late Eocene). To this day, most fossil records of the genus Loxoconcha belong to group A. Among the three subgroups of group A, species subgroup A1 is distributed widely in Indo-West Pacific Region, and therefore, subgroup A1 may be an origin group of the genus Loxoconcha. The geographical distribution of subgroups A2 and A3 mainly restricted within European marine water, including the Mediterranean Sea, meanwhile subgroup A1 lives around the World except for the distributional areas of subgroups A2 and A3, suggesting that the Atlantic Ocean may be a barrier to dispersing subgroups A1 and A2 (and A3).
Downloads
Metrics
References
[1] G. O. Sars, “Oversigt af Norges marine ostracoder,” Det Norske Videnskaps-Akademi Forhandlingar, vol. 8, pp. 1–130, 1866.
[2] G. S. Brady and A. M. Norman, “A monograph of the marine and freshwater Ostracoda of the North Atlantic and of North-western Europe. Section I. Podocopa,” Scientific Transactions of the Royal Dublin Society, vol. 4, pp. 63–270, 1889.
[3] S. Fischer, “Beitrag zur Kenntnis der Ostracoden,” Abhandlungen der Mathematisch-Physikalischen Klasse der Königlich Bayerischen Akademie der Wissenschaften, vol. 7, pp. 635–666, 1855.
[4] S. N. Brandão, M. V. Angel, I. Karanovic, A. Parker, V. Perrier, B. Sames, and M. Yasuhara, "World Ostracoda Database," World Register of Marine Species, Apr. 27, 2015. [Online]. Available: http://www.ma-rinespecies.org/aphia.php?p=taxdetails&id=127643 [accessed: October 26, 2024].
[5] K. Ishizaki, “Ostracodes from Uranouchi Bay, Kochi Prefecture, Japan,” Science Reports of the Tohoku University, Second Series (Geology), vol. 40, no. 1, pp. 1–45, 1968.
[6] I. Okubo, “Taxonomic studies on Recent marine podocopid Ostracoda from the Inland Sea of Seto,” Publications of the Seto Marine Biological Laboratory, vol. 25, no. 5–6, pp. 389–443, 1980.
[7] T. Ishii, T. Kamiya, and A. Tsukagoshi, “Phylogeny and evolution of Loxoconcha (Ostracoda, Crustacea) species around Japan,” Hydrobiologia, vol. 538, pp. 81–94, Mar. 2005.
[8] H. Ozawa, T. Ishii, and Y. Nakao, “Pore distributional patterns of Loxoconcha ikeyai (Crustacea: Ostracoda: Loxoconchidae) from the Lower Pleistocene Kakio Formation in Kanagawa Prefecture, central Japan,” Bulletin of the National Museum of Nature and Science, Series C (Geology & Paleontology), vol. 40, pp. 1–9, 2014.
[9] L. D. Dung and A. Tsukagoshi, “Three new species of the genus Loxoconcha (Crustacea, Ostracoda, Podocopida) from the Okinawa Islands, southern Japan,” Zootaxa, vol. 3796, no. 1, pp. 147–165, 2014.
[10] D. D. Le and A. Tsukagoshi, “Species composition of Ostracoda in the Okinawa islands, and geographical distribution of the two genera Loxoconcha and Xestoleberis (Arthropoda: Crustacea) around Japan,” Vietnam Journal of Marine Science and Technology, vol. 23, no. 3, pp. 279–291, 2023.
[11] H. Ozawa and T. Ishii, “Taxonomy and sexual dimorphism of a new species of Loxoconcha (Podocopida: Ostracoda) from the Pleistocene of the Japan Sea,” Zoological Journal of the Linnean Society, vol. 153, no. 2, pp. 239–251, 2008.
[12] G. Tanaka, T. Komatsu, and N. D. Phong, “Recent ostracod assemblages from the northeastern coast of Vietnam and the biogeographical significance of the euryhaline species,” Micropaleontology, vol. 55, no. 4, pp. 365–382, 2009.
[13] L. D. Dung and A. Tsukagoshi, “First report on two ostracod genera Loxoconcha Sars, 1866 (Loxoconchidae) and Xestoleberis Sars, 1866 (Xestoleberididae) along the coast of Vietnam,” Academia Journal of Biology, vol. 41, no. 4, pp. 15–24, 2019.
[14] K. Yamada, “Spatial and temporal distribution of fossil ostracode assemblages and sedimentary facies in the Lower Miocene Arakida Formation, Tomikusa Group, Nagano Prefecture, central Japan,” Journal of the Geological Society of Japan, vol. 107, no. 1, pp. 1–13, 2001.
[15] T. Irizuki, K. Yamada, T. Maruyama, and H. Ito, “Paleoecology and taxonomy of Early Miocene Ostracoda and paleoenvironments of the eastern Setouchi Province, central Japan,” Micropaleontology, vol. 50, no. 2, pp. 105–147, 2004.
[16] J. Athersuch, “On Sagmatocythere napoliana (Puri),” A Stereo-Atlas of Ostracod Shells, vol. 3, no. 21, pp. 117–124, 1976.
[17] J. Athersuch, “On Bonnyannella robertsoni (Brady),” Stereo-Atlas of Ostracod Shells, vol. 9, no. 14, pp. 77–84, 1982.
[18] F. M. Swain and J. M. Gilby, “Marine Holocene Ostracoda from the Pacific coast of North and Central America,” Micropaleontology, vol. 20, no. 3, pp. 257–353, 1974.
[19] D. J. Horne and R. C. Whatley, “On Palmoconcha laevata (Norman),” Stereo-Atlas of Ostracod Shells, vol. 12, p. 158, 1985.
[20] J. Athersuch and D. J. Horne, “A review of some European genera of the Family Loxoconchidae (Crustacea: Ostracoda),” Zoological Journal of the Linnean Society, vol. 81, no. 1, pp. 1–22, 1984.
[21] J. Athersuch, D. J. Horne, and J. E. Whittaker, Marine and Brackish Water Ostracods (Superfamilies Cypridacea and Cytheracea): Keys and Notes for the Identification of the Species, vol. 43, Synopses of the British Fauna (New Series). Leiden, Netherlands: E.J. Brill, 1989.
[22] I. Yassini and B. G. Jones, “Foraminiferida and Ostracoda from estuarine and shelf environments on the southeastern coast of Australia,” Journal of Foraminiferal Research, vol. 26, no. 3, p. 273, 1996.
[23] D. D. Le, A. Tsukagoshi, and T. Hayato, “Ontogenetic changes of the maxillula in Loxoconcha (Crustacea, Ostracoda, Podocopida), with a description of a new species from the Okinawa Islands (Japan),” Zoologischer Anzeiger-A Journal of Comparative Zoology, vol. 262, pp. 43–56, 2016.
[24] H. Chung, “Studies on ostracod faunas from the Hengchun Limestone (Pleistocene), southern Taiwan,” Quarterly Journal of the Taiwan Museum, vol. 34, no. 1&2, pp. 61–93, Jun. 1981.
[25] D. D. Le and A. Tsukagoshi, “Three new species of the genera Loxoconcha and Xestoleberis (Crustacea, Ostracoda, Podocopida) from central and southern Vietnam,” Zootaxa, vol. 4472, no. 1, pp. 111–126, 2018.
[26] Y. Nakao and A. Tsukagoshi, “Brackish-water Ostracoda (Crustacea) from the Obitsu River Estuary, central Japan,” Species Diversity, vol. 7, no. 1, pp. 67–115, 2002.
[27] W. A. van den Bold, “Ostracoda of the La Boca Formation, Panama Canal Zone,” Micropaleontology, vol. 18, no. 4, pp. 410–442, 1972.
[28] K. Ishizaki, “Japanese Miocene ostracodes from the Sunakosaka member of the Yatsuo formation, east of Kanazawa city, Ishikawa Prefecture,” Japanese Journal of Geology and Geography, vol. 34, no. 1, pp. 19–34, 1963.
[29] S. Tsukawaki, H. Ozawa, H. Domitsu, Y. Tanaka, T. Kamiya, M. Kato, and M. Oda, “Preliminary results from the RV Tansei-maru Cruise KT97-15 in the eastern marginal part of the Japan Sea off Tsugaru Peninsula, northeast Japan—sediments, benthic and planktonic foraminifers, and ostracodes,” Bulletin of Japan Sea Research Institute, no. 30, pp. 99–140, 1999.
[30] G. S. Brady, A Monograph of the Recent British Ostracoda, vol. 26. London: Taylor & Francis, 1868.
[31] H. S. Puri, “Preliminary notes on the Ostracoda of the Gulf of Naples,” Experientia, vol. 19, no. 7, pp. 368–373, 1963.
[32] R. Tabuki, “Plio-Pleistocene Ostracoda from the Tsugaru Basin, North Honshu, Japan,” Bulletin of the Faculty of Education, University of the Ryukyus, vol. 29, pp. 27–160, 1986.
[33] B. Zhou, “Recent ostracode fauna in the Pacific off Southwest Japan,” Memoirs of the Faculty of Science, Kyoto University. Series of Geology and Mineralogy, vol. 57, no. 2, pp. 21–98, 1995.
[34] C.-H. Hu, “Ostracoda from the Maanshan Mudstone, Hengchun Peninsula, Southern Taiwan,” Petroleum Geology of Taiwan, vol. 19, pp. 149–178, 1983.
[35] H. V. Howe and J. Chambers, “Louisiana Jackson Eocene Ostracoda,” Louisiana Geological Survey Geological Bulletin, no. 5, pp. 1–65, 1935.
[36] J. E. Hazel, M. D. Mumma, and W. J. Huff, “Ostracode biostratigraphy of the lower Oligocene (Vicksburgian) of Mississippi and Alabama,” Gulf Coast Association of Geological Societies Transactions, vol. 30, pp. 361–401, 1980.
[37] K. G. McKenzie, R. A. Reyment, and E. R. Reyment, “Eocene-Oligocene Ostracoda from South Australia and Victoria, Australia,” Revista Española de Paleontología, vol. 6, no. 2, pp. 135–175, 1991.
[38] K. G. McKenzie, R. A. Reyment, and E. R. Reyment, “Eocene Ostracoda from the Browns Creek Clays at Browns Creek and Castle Cove, Victoria, Australia,” Revista Española de Paleontología, vol. 8, no. 1, pp. 75–116, 1993.
[39] T. M. Cronin and H. Khalifa, “Middle and late Eocene Ostracoda from Gebel El Mereir, Nile Valley, Egypt,” Micropaleontology, vol. 25, no. 4, pp. 397–411, 1979.
[40] M. Ahmad, J. W. Neale, and Q. A. Siddiqui, “Tertiary Ostracoda from the Lindi area, Tanzania,” Bulletin of the British Museum (Natural History), Geology, vol. 46, no. 2, pp. 175–270, 1991.
[41] A. J. Keij, Eocene and Oligocene Ostracoda of Belgium, vol. 136. Brussels, Belgium: Institut Royal des Sciences Naturelles de Belgique, 1957
[42] M. A. Ayress, “Late Eocene Ostracoda (Crustacea) from the Waihao District, South Canterbury, New Zealand,” Journal of Paleontology, vol. 69, no. 5, pp. 897–921, 1995.
[43] T. Ishii, Phylogeny and Evolution of the Genus Loxoconcha and Related Genera (Ostracoda, Crustacea), Ph.D. dissertation, Kanazawa Univ., Kanazawa, Japan, 2004, pp. 1–85.
[44] D. D. Le, “Variation of number of pores on the carapaces of Group A species of the genus Loxoconcha (Crustacea, Ostracoda) following the molting,” Zoodiversity, vol. 58, no. 1, pp. 69–78, 2024.
[45] J. C. Briggs, Global Biogeography, vol. 14. Elsevier, 1995, 451 p.
[46] J. M. Leis, “Larval fish dispersal and the East Pacific Barrier,” Océanographie Tropicale, vol. 19, no. 2, pp. 181–192, 1984.
[47] W. K. Emerson, “First records for Cynatium mundum (Gould) in the Eastern Pacific Ocean with comments on the zoogeography of the tropical trans-Pacific tonnacean and non-tonnacean prosobranch gastropods with Indo-Pacific faunal affinities in the West American waters,” The Nautilus, vol. 105, no. 2, pp. 62–80, 1991.
[48] A. Tsukagoshi, “Ontogenetic change of distributional patterns of pore systems in Cythere species and its phylogenetic significance,” Lethaia, vol. 23, no. 3, pp. 225–241, 1990.
[49] A. Tsukagoshi, “Ontogenetic change of distributional patterns of pore systems in Cythere species and its phylogenetic significance,” Lethaia, vol. 23, no. 3, pp. 225–241, 1990. [In Japanese].
[50] R. Titterton and R. C. Whatley, “The provincial distribution of shallow water Indo-Pacific marine Ostracoda: origins, antiquity, dispersal routes and mechanisms,” in Developments in Palaeontology and Stratigraphy, vol. 11, P. J. F. Brenchley, (Ed.). Amsterdam, Netherlands: Elsevier, 1988, pp. 759–786.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2025 Vietnam Academy of Science and Technology

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.