Understanding the distribution patterns and formation mechanisms of endemic taxa is essential for effective biodiversity conservation. China is an important distribution and endemic center for genus Viburnum in Asia. However, the distribution pattern and formation mechanism of endemic taxa of Viburnum remains unclear in China. In this study, we determined the distribution information of 61 endemic taxa of Viburnum through specimens’ review and field surveys. Species distribution models were used to clarify the distribution patterns of the endemic taxa of Viburnum. The findings shows that the hotspot for overall endemic taxa of Viburnum in China is mainly distributed in temperate and subtropical mountainous areas, and the highest richness in the mountainous regions were around the Yunnan-Guizhou Plateau and the Sichuan Basin. About one-third of the endemic taxa of Viburnum were rare species, whose distribution area was scattered and lacked protection. The distribution pattern of the endemic taxa of genus Viburnum can be well explained within the three hypotheses of environmental energy, water availability and climate seasonality. This study provides additional understanding and explanation of endemic species richness distribution and their formation mechanisms. In addition, it provides conservation measures for endemic taxa of genus Viburnum to guide conservationists and policy makers in China.

Viburnum laterale Rehder is a poorly known shrub endemic to southeastern China that has remained taxonomically unresolved since its publication more than a century ago. The species was known only from a few historical collections that lacked critical characters, and no living populations had been documented for nearly a century. Here, we report the rediscovery of this taxon and clarify its taxonomic identity using an integrative approach combining morphological and molecular evidence. Observations of living plants reveal several previously undocumented reproductive traits, including inflorescences with conspicuous white sterile marginal flowers, as well as fruit and seed morphology. Comparative analyses of living material, type specimens, and protologues indicate that V. laterale is most similar to V. hanceanum Maximowicz, with V. laterale differing mainly in its nearly absent indumentum, longer peduncles, and more coarsely serrate leaf margins. Phylogenetic analyses based on chloroplast coding sequences, together with an expanded dataset comprising nuclear ribosomal internal transcribed spacer (nrITS) and three plastid markers ( mat K, ndh F, and rbc L), consistently place V. laterale within sect. Tomentosa (Maximowicz) Nakai, where it forms a strongly supported clade with V . hanceanum . Based on morphological and molecular evidence, V. laterale is transferred to sect. Tomentosa and treated as a variety of V . hanceanum , namely V. hanceanum var. depilatum M. Tang & L.C. Zhao. Our study resolves a long‐standing taxonomic problem and highlights the importance of rediscovering historically ambiguous taxa for accurate species delimitation in Viburnum .