Ammonia maruhasii (Kuwano)

Hanagata, S & Nobuhara, T, 2015, Illustrated guide to Pliocene foraminifera from Miyakojima, Ryukyu Island Arc, with comments on biostratigraph, Palaeontologia Electronica (Cambridge, England) 33 (8), pp. 1-142 : 118-119

Ammonia maruhasii (Kuwano)

Figure 35.3-35.6

1950 Rotalia maruhasii Kuwano , pp. 314, 315, text-figs. 2, 8.

1968 Ammonia ketienziensis angulata (Kuwano) — Huang, p. 55, pl. 12, figs. 8a, b (non Streblus ketienziensis Ishizaki, 1948 ).

1988 Ammonia maruhasii (Kuwano) — Wang, Zhang, Zhao, Min, Bian, Zheng, Cheng, and Chen, pp. 166, 167, pl. 26, figs. 14, 15, pl. 27, fig. 11.

Remarks. High trochospiral variation is included in this species. This species is distinguished from Rotalia ketienziensis Ishizaki in the lesser number of chambers, radial sutures, and less developed umbilical ornament. It also distinguished from Rotalia ketienziensis angulata Kuwano in having a more rounded periphery and radial sutures. It might be a Pliocene ancestral form of these modern Ammonia species.

Occurrence. Abundant in the Oura and Onogoshi formations, common in the Yonahama and Minebari formations.

Figures

FIGURE 35. Family Rotaliidae. All scale bars = 0.1mm, unless otherwise indicated. 1, 2. Pararotalia cf. nipponica (Asano), 1: MPC-26407, 2: MPC-26408, both from sample MK02B (Minebari Formation, PL5). 3—6. Ammonia maruhasii (Kuwano), 3: MPC-26112 from sample 18 (Oura F.,?PL1); 4: MPC-26113 from sample MK02B (Minebari F., PL5); 5: MPC-26114 from sample 3-2-up-sand (Onogoshi F., PL1); 6: MPC-26115 from sample MK01 (Yonahama F., PL2); 5 and 6, high trochospiral variety. 7, 8. Ammonia parkinsoniana (d'Orbigny), 7: MPC-26116 from sample 14 (Yonahama F., PL4); 8: MPC-26117 from sample 14-2 (Yonahama F., PL4). 9, 10. Asterorotalia pulchella (d'Orbigny), 9: MPC-26134 from sample 10 (Onogoshi F., PL2); 10: MPC-26135 from sample 18 (Oura F.,?PL1). 11, 12. Rotalinoides compressiuscula (Brady), 11: MPC-26466 from sample 5-2 (Minebari F., PL5); 12: MPC-26467 from sample 18 (Oura F.,?PL1).