Gyroidinoides sp. A

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 : 116

Gyroidinoides sp. A

Figures 34.5, 34.6

Description. Test small for the genus; plano-convex; umbilical side more convex; umbilicus almost closed but depressed; chambers slightly inflated; sutures slightly depressed, and those of dorsal side strongly curved backwards and those of umbilical side radiating; aperture at interio-marginal slit extending from periphery to umbilicus; surface smooth and very finely perforated.

Remarks. This species is distinguished from congeners in having strongly curved sutures on the dorsal side; however, its small size suggests that this species might represent the juvenile stage of another species of Gyroidinoides .

Occurrence. Sporadic in the Onogoshi, Yonahama, and Minebari formations.

Figures

FIGURE 34. Family Gavelinellidae. All scale bars = 0.1mm. 1, 2. Gyroidinoides aff. gemmus (Bandy), 1: MPC-26304 from sample 17 (Yonahama Formation, PL2); 2: MPC-26305 from sample MK01 (Yonahama F., PL2). 3, 4. Gyroidinoides soldanii (d'Orbigny), 3: MPC-26306 from sample 3-2-low-silt (Onogoshi F., PL1); 4: MPC-26307 from sample MK01 (Yonahama F., PL2). 5, 6. Gyroidinoides sp.A, 5: MPC-26308 from sample 3-2-low-silt (Onogoshi F., PL1); 6: MPC-26309 from sample 8 (Yonahama F., PL4). 7, 8. Gyroidina nipponica Ishizaki, 7: MPC-26296 from sample 11 (Onogoshi F.,?PL1); 8: MPC-26297 from sample MK02B (Minebari F., PL5). 9, 10. Gyroidina sp.A, 9: MPC-26298 from sample 15 (Yonahama F., PL3); 10: MPC-26299 from sample MK02A-2 (Minebari F., PL5). 11, 12. Hanzawaia asterizana (Fichtel and Moll), 11: MPC-26310 from sample 2 (Minebari F., PL5); 12: MPC-26311 from sample MK02A (Minebari F., PL5). 13. Hanzawaia cf. coronata (Heron-Allen and Earland), MPC-26312 from sample MK01 (Yonahama F., PL2). 14, 15. Hanzawaia nipponica Asano, 14: MPC-26313 from sample 4 (Minebari F., PL5); 15: MPC- 26314 from sample 18 (Oura F.,?PL1).