Cycas taitungensis C.F.Shen, K.D.Hill, C.H.Tsou & C.J.Chen had been synonymized under Cycas revoluta Thunb. based on both morphological and genetic evidence.

Chang, J. T., Chao, C. T., Nakamura, K., Liu, H. L., Luo, M. X., & Liao, P. C. (2022). Divergence With Gene Flow and Contrasting Population Size Blur the Species Boundary in Cycas Sect. Asiorientales, as Inferred From Morphology and RAD-Seq Data. Frontiers in Plant Science, 957.

https://www.frontiersin.org/articles/10.3389/fpls.2022.824158/full?fbclid=IwAR2hDHXs_PTMI-U_oKNDiuDddmkJrL44YJJB-SpHGeKBozzl9VhRqOsDbgI

This treatment has also been updated on POWO:
https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:978052-1