Systematic Position of <i>Citrus cavaleriei</i>: Argument for an Independent Subgenus Based on Multidimensional Evidences

<i>Citrus cavaleriei</i>, a wild germplasm resource within the genus <i>Citrus</i> of the Rutaceae family, holds significant breeding value and a unique taxonomic position. Its systematic status has long been debated, primarily concerning whether it belongs to the <i>Citrus</i> subgenus <i>Papeda</i>, the <i>Citrus </i>subgenus <i>Metacitrus</i>, or should be classified as a distinct genus. To clarify its taxonomic status, this study integrated multi-dimensional research methods—including literature review, comparative morphology, molecular phylogenetic analysis, cytological observation, and ecological adaptability assessment. A multi-evidence framework demonstrates that <i>C. cavaleriei</i>, constitutes an independent evolutionary unit. Morphologically, its winged leaf proportions, floral structures, and seed characteristics distinctly differ from both <I>C.</I> subgenus <i>Papeda</i> and <I>C.</I> subgenus<i> Metacitrus</i>. Molecular systematics confirms it forms an independent phylogenetic branch, with its unique genetic diversity patterns and cold-tolerant gene resources further supporting its distinct subgenus status. Karyotype analysis reveals markedly unique chromosomal architecture in<i> C. cavaleriei</i>. Furthermore, its unique adaptations and restricted alpine ecological niche create effective reproductive isolation from other citrus groups. Therefore, comprehensive data support establishing <i>C. cavaleriei</i> as an independent subgenus within <i>Citrus</i>. This conclusion not only resolves long-standing taxonomic controversies surrounding <i>C. cavaleriei</i> but also provides a theoretical basis for refining the <i>Citrus </i>taxonomic system and conserving and utilizing its germplasm resources. 宜昌橙（Citrus cavaleriei）作为芸香科（Rutaceae）柑橘属（Citrus）中具有重要育种价值与独特分类地位的野生种质资源，其系统学地位长期存在争议，其主要争议点在宜昌橙是归属于大翼橙亚属还是柑橘亚属，或是独立成类。为厘清其分类地位，本研究通过文献查阅，整合了形态学比较、分子系统学分析、细胞学观察及生态适应性评估等多维度分析方法。多证据皆表明了宜昌橙是一个独立的演化单元，在形态上宜昌橙的翼叶比例、花部结构和种子特性等特征显著区别于大翼橙亚属和柑橘亚属。分子系统学上确认其构成一个独立的系统发育分支，其特有的遗传多样性模式与抗寒基因资源也进一步支持其独立的亚属地位。核型分析显示，宜昌橙的染色体结构具有明显独特性。此外，其独特的适应性及其狭域高山生态位与其他柑橘类群形成了有效的生殖隔离。因此，综合数据支持将宜昌橙设立为柑橘属下的一个独立亚属。此结论不仅厘清了宜昌橙长期的分类学争议，也为柑橘属分类系统的完善和宜昌橙种质资源的保护与利用提供理论依据