Sematophyllum latifolium Brotherus (1911: 362), known only from the type collection, was originally described by Brotherus (1911) based on a collection made by C.C. Hosseus from Mt. Doi Suthep (Doi Sutäp), in northern Thailand. Pollawatn (2008) revised the family Sematophyllaceae s.l. in Thailand but did not see the type specimen of S. latifolium. During the study of Hosseus’s collections, however, we found two duplicates of type specimens of S. latifolium one located in H-BR and one in M. We found that several critical features of S. latifolium, such as the 1) irregular-pinnately branching habit with the erect flagelliform branches (Fig. 1A), 2) stem and branch leaves strongly differentiated (Fig. 1B−F), and 3) brotherelloid type alar cells often divided into larger hyaline cells towards leaf margins (Fig. 1G), were indistinguishable from those in the type material of Wijkia surcularis (Mitten 1859: 112) Crum (1971: 173), a common species found growing from India to Indochina (Gangulee 1980; Tan & Iwatsuki 1993; Tan & Jia 1999; Jia et al. 2005). Thus, we here propose S. latifolium as a new synonym of W. sucularis. In the protologue, Brotherus (1911) did not designate the holotype, therefore, it is necessary to select a lectotype for S. latifolium ((see Art. 9.11 of the Shenzhen Code (Turland et al. 2017)). We designate Hosseus’s collection (Hosseus s.n.) in H-BR (H) as the lectotype of the name S. latifolium.