Euploca formosana (Heliotropiaceae): A new combination from Taiwan

In Taiwan, six species of Heliotropium (Heliotropiaceae) have been documented, including Heliotropium strigosum Willd., a species now considered synonymous with Euploca strigosa, in Kinmen. The genus Euploca Nutt. was recognized as an independent genus from Heliotropium L. in 2003, based on molecular phylogenetic analysis using trnL and ITS1 sequence data, and the key morphological trait—the presence of pits on the endocarpid. In Euploca, the fruit separates into four nutlets, with pits on the endocarpid, whereas in Heliotropium, the fruit separates into two nutlets and lacks pits on the endocarpid. As a result of these diagnostic differences, H. procumbens var. depressum and H. strigosa were transferred to the genus Euploca. In this study, both morphological characteristics and molecular evidence demonstrate that H. formosanum aligns with species within the genus Euploca. Thus, we propose a new combination for Heliotropium formosanum as Euploca formosana (I.M.Johnst.) P.H.Chen & A.C.Chung.