Recent integrative systematic studies of Vitaceae support the recognition of a new genus Pseudocayratia J.Wen, L.M.Lu & Z.D.Chen. The genus consists of five species from China and Japan. We herein describe the following two new species: Pseudocayratia speciosa J.Wen & L.M.Lu, and P. pengiana Hsu & J.Wen, and make three new combinations: Pseudocayratia dichromocarpa (H.Lev.) J.Wen & Z.D.Chen, P. oligocarpa (H.Lev. & Van.) J.Wen & L.M.Lu, and P. yoshimurae (Makino) J.Wen & V.C.Dang. Phylogenetic analyses based on five chloroplast loci strongly support Pseudocayratia as sister to Tetrastigma. Morphologically, species of the genus have stigmas enlarged (but not 4-lobed), pedicels at fruiting stage enlarged and fleshy, seeds with a crustaceous thin testa, circular cup-like ventral infolds, linear chalaza extending ca. 2/3 to 3/4 of the seed length (from apex to base), lateral margin with thin edges, and T-shaped endosperm in cross-section. The genus is distributed in eastern Asia (China and Japan). The taxonomic novelties we report in this study at both the generic and species levels highlight the importance of collections-based research in today's integrative systematics.
