Clavatorella aff. suturanii Giannelli and Salvatorini

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 : 42

Clavatorella aff. suturanii Giannelli and Salvatorini

Figures 15.3, 15.4

Compared with:

1976 Clavatorella suturanii Giannelli and Salvatorini , p. 168, pl. 1, fig. 1.

1985 Clavatorella suturanii Giannelli and Salvatorini — Bolli and Saunders, 1985, p. 255, fig. 45.3.

2004 Clavatorella sp. 1 — Hanagata, pl. 3, fig. 9.

Diagnosis. Small species with four to four and a half, slightly elongated chambers in the final whorl, moderately perforated smooth surface without ornament, aperture small interiomarginal U-shaped opening from umbilicus to near the periphery. Outer margin of chambers is lobulate and occasionally apiculate.

Remarks. This form is distinguishable from C. suturanii in having less inflated and less lobulate chambers. Kadar (1975, pl. 8, fig. 59) illustrated a morphotype of Clavatorella (Clavatorella) bermudezi (Bolli) that is somewhat similar to the present form, but differs in having more elongated chambers and an umbilicus-oriented aperture. Clavatorella suturanii and C. bermudezi have both been recorded from the Miocene; thus the present form is probably a descendant.

Occurrence. Common in the Yonahama Formation, sporadic in the Minebari Formation.

Figures

FIGURE 15. Family Epistominidae and Globorotaliidae. All scale bars = 0.1mm, unless otherwise indicated. 1, 2. Hoeglundina elegans (d'Orbigny) large form, 1: MPC-26324 from sample 2-2 (Minebari Formation, PL5); 2: MPC- 26325 from sample 4 (Minebari F., PL5). 3, 4. Clavatorella aff. suturanii Giannelli and Salvatorini, 3: MPC-25930 from sample 5 (Minebari F., PL5); 4: MPC-25931 from sample MK01 (Yonahama F., PL2). 5, 6. Globorotalia conoidea Walters, 5: MPC-25968 from sample 7 (Yonahama F., PL4); 6: MPC-25969 from sample 8-2 (Yonahama F., PL4). 7, 8. Globorotalia conomiozea Kennett, 7: MPC-25970 from sample 3 (Onogoshi F., PL1); 8: MPC-25971 from sample 6 (Yonahama F., PL2). 9, 10. Globorotalia crassaformis (Galloway and Wissler), 9: MPC-25972 from sample MK02A (Minebari F., PL5); 10: MPC-25973 from sample MK02B (Minebari F., PL5). 11, 12. Globorotalia cultrata (d'Orbigny), 11: MPC-25974 from sample MK01 (Yonahama F., PL2); 12: MPC-25975 from sample MK02A (Minebari F., PL5).