Portlandia ( Megayoldia ) gratiosa (Yokoyama)
| 1957. | Portlandia (Megayoldia) gratiosa (Yokoyama) Syntype Makiyama, J. 1957 pl. 6, fig. 5a, b |
| 1923. | Yoldia gratiosa Yokoyama, 1923 Syntype Yokoyama, M. 1923c p. 8, pl. 2, fig. 5 |
| Condition: | Missing |
| Taxonomy: | Mollusca: Bivalvia: Yoldiidae: |
| Geologic Time: | Cenozoic: |
| Makiyama, J., 1957: Matajiro Yokoyama's Tertiary fossils from various localities in Japan. Part 1. Palaeontological Society of Japan, Special Papers, no. 3, pp. 1–4, pls. 1–24. (Reference No. 0367) |
| Yokoyama, M., 1923c: On some fossil Mollusca from the Neogene of Izumo. Japanese Journal of Geology and Geography, vol. 2, no. 1, pp. 1–9, pls. 1–2. (Reference No. 0469) |
| Ichikawa, T., 1983, no. 9, p. 45. |
| Ichikawa, T., 1983, no. 9, p. 293. |
