Introduction
The family Celastraceae contains about 60 genera with more than 850 species, and most of these species distributed in tropic, subtropic and temperate areas, with limited species radiated into cold temperate zone (Ma 2001, Ma et al. 2008, Li et al. 2014). The tribe Euonymeae is the majority of the family, containing eight genera with about 230 species in both the Old and New Worlds (Loesener 1942; Simmons et al. 1999, 2001, 2012). Tribe Euonymeae has been defined as those genera of Celastraceae with generally opposite leaves, isomerous carpels, loculicidally dehiscent capsules, and arillate seeds (Simmons et al. 2012). Phylogenetic studies on tribe Euonymeae indicate that the tribe consists of at least six separate lineages within Celastraceae and that a revised natural classification of the family is needed (Simmons et al. 2012). Furthermore, Euonymus is the most diverse (129 species) and widely cultivated genus in the tribe, and its current intrageneric classifications of Euonymus are not completely natural and require revision (Simmons et al. 2012, Li et al. 2014).
Euonymus L. is a worldwide distributed plant group, with a total of about 130 species worldwide (Li 2014). It originated in Europe, and now most species are widely distributed in Southeast Asia, with China as the center of diversity, and a few species are distributed in the Americas, Australia and Africa (Simmons et al. 2012, Li 2014). Due to the wide distribution area of the genus, the ecological environment factors such as geography and climate change greatly, resulting in abundant morphological variation within the genus. Although many study works are published, there are still many problems in the system and classification of Euonymus (Li 2014), which have also resulted in diversity inventory of the genus remaining ambiguous and some new species published recently (Li et al. 2024, Savinov et al. 2024).
In recent years, we have carried out multiple intermittent field expeditions in the northwestern regions of Guangxi, where is biodiversity hotspot of China and currently being prepared for the Southwest Karst National Park (Myers et al. 2000, Hou et al. 2010), we document a distinct Euonymus species. After careful study morphological characteristics and molecular evidence with its related species, we find the species is a new species of Euonymus to science.