Assuming this is Eurema hecabe [菏氏黃蝶] and not Eurema blanda arsakia [台灣黃蝶] then that would bring the total number of different species photographed at 55.
If you’re an expert at identifying insects and would like a challenge please don’t hesitate to double check the identifications at the Taiwan’s Butterflies page.
UPDATE: Nope, definitely another Eurema blanda arsakia. Still at 54 species.
The Daily Bubble Tea 
This should be 台灣黃蝶; its back wings are quite curved, but I can not see them very clearly. Watch whether the back down corner of its back wing is curved. If it’s not, then it is 菏氏黃蝶, and if it is, then it is 台灣黃蝶. You can use the pictures on the following two sites to help you:
http://insecta.idv.tw/wiki/index.php/%E5%8F%B0%E7%81%A3%E9%BB%83%E8%9D%B6
http://insecta.idv.tw/wiki/index.php/%E8%8D%B7%E6%B0%8F%E9%BB%83%E8%9D%B6
Kuei-Ti Lu,
Thank you for the clarification. I now see the differences between the two species!
It’s a beautiful butterfly.