Sarcophagodes duodecima Naya &amp; Mizuno 2021, sp. nov.
Creators: name: Naya, Tomonori
name: Mizuno, Kiyohide
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Chromista
Ochrophyta
Bacillariophyceae
Fragilariales
Fragilariaceae
Sarcophagodes
Sarcophagodes duodecima

description: <i>Sarcophagodes duodecima</i> Naya <i>sp. nov.</i> (LM: Figs 3–18, SEM: Figs 19–35) <b>Description</b>:—In LM, frustule rectangular in girdle view with round corners (Figs 17, 18), attached at valve face by interlocking spines (Fig.17). The larger valves are heteroplar clavate (Figs 4, 5, 7, 9, 10) or isopolar elliptic (Figs 3, 6, 8) and the smaller valves isopolar elliptic (Figs 11–16). Sternum widely lanceolate (Figs 12, 19). Striae alternate and robust (Fig. 12). Length 3–16 µm, width 2.5–3 µm, and striae density 8–10 in 10 µm. In SEM, striae uniseriate, composed of up to three areolae on the valve face and two to four on the mantle (Figs 19–22, 25–30). Areolae apically reniform at the ends of each stria, otherwise rectangular with rounded corners (Figs 20, 25–27, 29), occluded by one or multiple profusely branched volae with stalk-like rod extending from vimines (Figs 21, 26, 27, 30, 35). Marginal spines solid, spatulate (Fig. 19) or conical (Fig. 22), interrupting the striae on the thickened vimen at valve face-mantle junction (Figs 19, 25–30). Apical pore field present at both poles, consisting of multiple round pores present at both poles (Figs 30, 34, 35). Cingulum formed of up to eight wide open copulae (Figs 20, 29, 30). Valvocopula wider than other copulae. Edge of pars interior of valvocopula undulate (Fig. 23). Fringed structure observed at the end of copula (Fig. 21). Mantle plaques present (Figs 20, 29). No rimoportulae. <b>Type</b>:— JAPAN. Higashiomi, Oita Prefecture: Himeshima village, from siliceous silt of the Lower to Middle Pleistocene Karato Formation, sample 180327–2 D3, 33°43′30.0″ N, 131°40′20.1″ E, <i>T. Naya and Y. Horiuchi 27 March 2018</i> (holotype: slide MPC-44141= Fig. 12, Micropaleontology Collection, National Museum of Nature and Science, Tsukuba, Japan, England Finder M 35/0) <b>Etymology</b>:—Duodecim, Latin = twelfth, after a myth of Himeshima Island, where the type locality is situated. According to the Kojiki, the oldest extant chronicle in Japan (Kurano 1963), Himeshima Island was the twelfth island in the Japanese archipelago to be created. <b>Observation</b>:—The isopolar valves are observed in the entire size range of the species, whereas the heteropolar valves are recognized in only approximately half of the larger valves (&gt;10 µm). However, due to the small proportion of the larger valves, few heteropolar valves occurred in the analyzed samples (Figs 4, 5, 7, 9, 10, 23, 30). Vimines are thickened at the valve-face mantle junction (Figs 26–27). Each thickened vimen can be observed as a distinct bar crossing the middle of the stria in internal view under SEM (Figs 24, 32, 33); the vimines are also visible vaguely under LM (Figs 5, 6, 11). A reduced apical pore field is observed at both poles, consisting of multiple round pores. In most specimens, the apical pore field could not be observed in external view, and could be seen only at the foot pole of the heteropolar valve (Fig. 30). Mantle plaques are arranged along the external rim of the mantle (Figs. 20, 29). <b>Distribution and geologic age</b>:—Thus far, <i>S. duodecima</i> has been found at two localities in Japan. The type locality of the species is in the Karato Formation on Himeshima Island, western Japan. The age of these sediments is inferred to be ca. 0.78 Ma. The other locality is in the Lower Pleistocene Bushi Formation in Iruma City, Saitama Prefecture, central Japan (Fig. 1). <i>S. duodecima</i> occurs in the M1 and M2 marine beds in the Bushi Formation (Figs 36–45); the age of these beds is estimated to be 2.5–2.4 Ma (Naya and Mizuno 2020).
description: Published as part of <i>Naya, Tomonori &amp; Mizuno, Kiyohide, 2021, Sarcophagodes duodecima sp. nov., a new small araphid fossil diatom (Bacillariophyceae) from Lower to Middle Pleistocene sediments of Japan, pp. 85-96 in Phytotaxa 505 (1)</i> on pages 88-91, DOI: 10.11646/phytotaxa.505.1.6, http://zenodo.org/record/5425268
description: {"references": ["Kurano, K. (revision and annotation). (1963) Kojiki. Iwanami Shoten Publishers, Tokyo, 382 pp. [in Japanese]", "Naya, T. &amp; Mizuno, K. (2020) A re-examination of stratigraphy and age of the Lower Pleistocene Bushi Formation in the Kaji Hills, western Kanto Plain, central Japan. The Journal of the Geological Society of Japan 126: 183 - 204. [in Japanese with English abstract] https: // doi. org / 10.5575 / geosoc. 2020.0005"]}