本文描述一臺灣新歸化五加科（Araliaceae）植物－銳裂天胡荽（Hydrocotyle acutiloba），迄今僅見於台灣北部。主要分佈於向陽開闊的低矮草叢中。原產於澳大利亞東海岸，分布於昆士蘭到維多利亞。本文提供特徵描述、其與臺灣天胡荽屬植物之檢索表、分布圖及照片，以供鑑定參考。

Hydrocotyle acutiloba (Araliaceae) is a newly naturalized plant in Taiwan, currently found only in the northern part of Taiwan, mainly distributed in sunny open low grasslands. It is native to the east coast of Australia, ranges from Queensland to Victoria. Descriptions, a key distribution map, and images of the species are provided.