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Bicornucythere concentrica sp. nov. (Figs 4 A���I and 6) Type material. Holotype, UMUT-CA 31128, carapace; paratype, UMUT-CA 31129, right valve, UMUT-CA 31130, left valve, UMUT-CA 31131, carapace. Diagnosis. A species of Bicornucythere characterized by a medium-sized carapace and concentric reticulation with polygonal fossae and sharp muri. Description. Carapace robust and medium in size (length, 569���654 ��m). Left valve slightly larger than right. In external view: lateral outline subrectangular; anterior margin rounded; posterior margin bluntly angular; dorsal margins slightly sinuated; ventral margin curved. Maximum length along middle of carapace; maximum height through anterodorsal point; maximum width across carapace, one-third of the distance from posterior to anterior ends. Surface ornamented with concentric reticulation formed by polygonal fossae and sharp muri. Polygonal fossae present on upper half of carapace; elongated fossae exist on lower half. Muri parallel to anterior and ventral margins in both anterior and ventral areas. Spine projecting in posteroventral area. Marginal denticles present along anterior margin. Eye tubercle present below anterodorsal point. In dorsal view: anterior margin narrow at one-sixth the distance from anterior to posterior ends, and tapering toward anterior end; posterior margin bluntly angular; lateral margins broadly curved with weakly indented near middle of margin. On hingement of right valve, triangular teeth present in both anterior and posterior elements. In anterior view: ovate outline; angular dorsal margin, forming apex; ventral margin angular, flattened on bottom; lateral margins gently curved. In internal view: anterior marginal infold broad; hingement amphidont-type. In right valve of hingement: anterior element with colonial tooth and a socket behind the tooth; posterior element with colonial tooth. Measurements. UMUT-CA 31128, holotype, L = 569 ��m, H = 326 ��m; UMUT-CA 31129, paratype, L = 654 ��m, H = 353 ��m; UMUT-CA 31130, paratype, L = 651 ��m, H = 325 ��m; UMUT-CA 31131, paratype, L = 580 ��m, H = 349 ��m. Type locality. The horizon of sample 69 - 1 is 464 m above the base of the Yaw Formation in the Kyauktakha section, Myanmar (21 �� 26.693 ���N, 94 �� 18.853 ���E) (Figs 1 and 2). Etymology. ���Concentric��� in Latin. Named after its concentric reticulation, which is a diagnostic trait for this species. Remarks. We identified A, A- 1, and A- 2 instars based on our measurements of 110 values of B. bisanensis (Fig. 5). During molting from the A- 1 to the A stage, the mean L and mean H of B. bisanensis increased 1.31 and 1.16 times, respectively, corresponding to an increase in the valve area of 1.52 times (the product of 1.31 and 1.16). The 95 % CI of the WM/L ratio in the A stage is 9.3 �� 10 ��� 2 to 10 �� 10 ��� 2, and in the A- 1 stage is 4.5 �� 10 ��� 2 to 4.9 �� 10 ��� 2. The permutation test indicates that the WM/L ratios of adults and juveniles are significantly different (see Appendix). Specimens UMUT-CA 31129 and UMUT-CA 31130 are both considered adults. The WM/L ratios of specimens UMUT-CA 31129 and UMUT-CA 31130 are 8.7 �� 10 ��� 2 and 9.7 �� 10 ��� 2, respectively; the ratios are almost within the 95 % CI of adult B. bisanensis (Fig. 5 C). The holotype is smaller than specimen UMUT-CA 31129, suggesting that the holotype may be a juvenile. However we consider the holotype to be an adult, because the difference in valve size between the paratype and the holotype is smaller than the size difference between instars. According to Kesling (1953), who proposed a method to identify instars of fossil ostracodes, ostracodes increase their valve area by ~ 1.59 times after molting. In our measurement of B. bisanensis, the valve area of the A is 1.52 times that of the A- 1 instar. Specimen UMUT-CA 31129 is 1.15 times longer and 1.09 times taller than the holotype and has a valve area 1.25 times larger than the holotype. Thus, the differences in size between the type specimens are considered to represent size variations within an instar stage. A carapace ornamented with reticulation and posteroventral spines is present in Ruggieria Keij, 1957, Keijella Ruggieri, 1967, Bicornucythere Schornikov & Shaitarov, 1979, Borneocythere Mostafawi, 1992, and Venericythere Mostafawi, 1992 (Table 2). These genera are reported from modern marine sediments in Asia (e.g., Whatley & Zhao 1988; Mostafawi 1992). The lateral outline of the new taxon is different from that of Venericythere. The absence of a ventral longitudinal carina in the new species distinguishes it from Ruggieria. Because Keijella and Borneocythere have a swelled tooth and two teeth in the anterior hinge element of the right valve, the new species cannot be assigned to either of these genera. The new taxon possesses a posterior margin without marginal denticles, as in Bicornucythere bisanensis. Hence, we identified the genus of the new taxon as Bicornucythere. A subrectangular carapace with concentric reticulation is present in Pistocythereis Gou in Gou et al. 1983, which is also distributed in Asia (Table 2). However, Pistocythereis possesses marginal denticles on the posterior margin and lacks postero-ventral spines. Genus Ruggieria Keij, 1957 Keijella Ruggieri, 1967 Bicornucythere Schornikov & Staitarov, 1979 continued. Genus Pistocythereis Gou, 1983 Borneocythere Mostafawi, 1992 Venericythere Mostafawi, 1992 Type species Echinocythereis bradyi Keijiella paucipunctata Whatley Cythere darwini Brady, 1868 Ishizaki, 1968 & Zhao, 1988 Bicornucythere concentrica sp. nov. differs from B. secedens (Lubimova & Guha in Lubimova et al. 1960) in having concentrically arranged fossae in lateral view and a narrow anterior margin one-sixth of the distance from the anterior end in dorsal view. Bicornucythere secedens was originally described as a species of Cytheretta M��ller, 1894, based on specimens from lower Miocene deposits of Kutch, western India. This new species is different from B. bisanensis (Okubo, 1975) and the Bicornucythere sp. of Yasuhara & Irizuki (2001) in having a smaller carapace and reticulation with polygonal fossae and sharper muri. These species are commonly found in Japanese enclosed bays (e.g., Irizuki et al. 2009). Bicornucythere concentrica sp. nov. is similar to Keijella mutata (Lubimova & Guha, 1960 in Lubimova et al. 1960), Keijella reticulata Whatley & Zhao, 1988, and Borneocythere papuensis (Brady, 1880) in the shape of the lateral outline and the distinctive reticulation. The new species is distinguished from these taxa by having a smaller carapace covered with concentric reticulation, reticulation with narrower muri and polygonal fossae, while the described taxon possesses reticulation with distinct longitudinal muri and rectangle fossae. Keijella mutata was originally described from lower Miocene deposits in Kutch. Keijella reticulata and Boreocythere papuensis are found in modern sediments in Southeast Asia, such as in Papua and Borneo (e.g., Whatley & Zhao 1988; Mostafawi 1992)., Published as part of Yamaguchi, Tatsuhiko, Suzuki, Hisashi, Soe, Aung-Naing, Htike, Thaung, Nomura, Ritsuo & Takai, Masanaru, 2015, A new late Eocene Bicornucythere species (Ostracoda, Crustacea) from Myanmar, and its significance for the evolutionary history of the genus, pp. 306-326 in Zootaxa 3919 (2) on pages 312-316, DOI: 10.11646/zootaxa.3919.2.4, http://zenodo.org/record/237794, {"references":["Kesling, R. V. (1953) A slide rule for the determination of instars in ostracod species. Contributions from the Museum of Paleontology University of Michigan, 11, 97 - 109.","Keij, A. J. (1957) Eocene and Oligocene Ostracoda of Belgium. Memoires, Institut Royal des Sciences Naturelles de Belgique, 136, 1 - 210.","Ruggieri, G. (1967) Due ostracofaune del Miocene alloctono della Val Marecchia (Appennino Settentrionale). Rivista italiana di paleontologia, 73, 351 - 384.","Schornikov, E. I. & Shaitarov, S. V. (1979) A new genus of ostracods from Ear-eastern seas. Biologija Morija, 2, 41 - 47. [Russian with English abstract]","Mostafawi, N. (1992) Rezente Ostacoden aus dem Mittleren Sunda-Schelf zwischen der Malaiischen Halbinsel und Borneo. Senckenbergiana Lethaea, 72, 129 - 168.","Whatley, R. & Zhao, Q. (1988) Recent Ostracoda of the Malacca straits part II. Revista Espanola de Micropaleontologia, 20, 5 - 37.","Gou, Y. S., Zheng, S. Y. & Huang, B. R. (1983) Pliocene ostracode fauna of Leizhou Peninsula and northern Hainan Island, Guangdong Province. Palaeontologia Sinica, New Series B, 18, 1 - 134.","Brady, G. S. (1868) Chapitre XV: Abords de l'ile North-Watcher. In: De Folin, L. & Perier, L. (Eds.), Les Fonds de la Mer. Etude sur les particularites nouvelles des regions sous-marines, Tome Premier, Savy, Paris, pp. 70 - 72.","Ishizaki, K. (1968) Ostracodes from Uranouchi Bay, Kochi Prefecture, Japan. Science Report of the Tohoku University, Sendai, Japan Second Series (Geology), 40, 1 - 45.","Muller, G. W. (1894) Die Ostracoden des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. Fauna und Flora des Golfes von Neapel und der angrenzenden Meeres-Abschnitte. Herausgegeben von der Zoologischen Station zu Neapel, Monographie, 21, 1 - 404.","Okubo, I. (1975) Callistocythere pumila Hanai, 1957 and Leguminocythereis bisanensis sp. nov. in the inland sea, Japan (Ostracoda). Proceedings of the Japanese Society of Systematic Zoology, 11, 23 - 31.","Yasuhara, M. & Irizuki, T. (2001) Recent Ostracoda from the northwestern part of Osaka Bay, southwestern Japan. Journal of Geosciences Osaka City University, 44, 57 - 95.","Lubimuva, P. S., Guha, D. K. & Mohan, M. (1960) Ostracoda of Jurassic and Tertiary deposits from Kutsch and Raajasthahan (Jaisalmer), India. Bulletin of the Geological, Mining and Metallurgical Society of India, 22, 1 - 61.","Brady, G. S. (1880) Report on the Ostracoda dredged by H. M. S. Challenger during the years 1873 - 1876. Report on Scientific Result of the voyage of H. M. S. Challenger during the years 1873 - 76 Zoology, 1, 1 - 184."]}

Yamaguchi, Tatsuhiko, Suzuki, Hisashi, Soe, Aung-Naing, Htike, Thaung, Nomura, Ritsuo, Takai, Masanaru (2015): A new late Eocene Bicornucythere species (Ostracoda, Crustacea) from Myanmar, and its significance for the evolutionary history of the genus. Zootaxa 3919 (2): 306-326, DOI: http://dx.doi.org/10.11646/zootaxa.3919.2.4

金沢大学国際基幹教育院GS教育系, 島根半島に分布する中部中新統古江層より，介形虫化石群を報告した．本群集はMacrocypris sp., Palmoconcha saboyamensis, Falsobuntonia hayamiiおよびPalmenella limicolaで特徴づけられる．同様なMacrocypris属が卓越する群集は，現在の島根半島沖の寒冷な下部陸棚域に認められる．このことから，本化石群は下部陸棚の環境を示唆すると考えられる．, This report provides the first description of ostracod assemblages from the Middle Miocene Furue Formation, Shimane Peninsula, Southwest Japan. The assemblage consists mainly of Macrocypris sp., Palmoconcha saboyamensis, Falsobuntonia hayamii and Palmenella limicola. Based on a comparison among Recent ostracod assemblages, the reported fossil assemblage indicates a cool lower-shelf environment similar to the Recent off Shimane Peninsula.

In the last 15 years from 1982 to 1997, Japanese foraminiferologists have made a significant contribution to the ecological researches of recent benthic foraminifera around the Japanese Islands. Nine genera and 36 species have been proposed within this period of time This is an alphabetic list of benthic foraminiferal taxa reported after the publication of Nomura (1982,1983).