This is the opening paper in the special issue of Fungal Diversity, which collates the data on defining species. Defining and recognizing species has long been a controversial issue. Since Darwin's proposed origin of species, over 30 species criteria have been brought forth and used to define species boundaries. In recent times, phylogenetic analyses based on multiple loci have been extensively used as a method to define species boundaries. However, only a few mycologists are aware that phylogenetic species criteria can mask discordances among fungal groups, leading to inaccurately defined species boundaries. In the current review, we discuss species recognition criteria, how and where these criteria can be applied along with their limitations and derived alternatives. In order to delimit fungal species, authors need to take into account not only the phylogenetic and phenotypic coherence, but also the timing of events that lead to fungal speciation and subsequent diversifications. Variations in the rate of phenotypic diversifications and convergent fungal evolution make it difficult to establish a universal species recognition criterion. The best practice can only be defined in the context of each fungal group. In this review, we provide a set of guidelines, encouraging an integrative taxonomic approach for species delimitation that can be used to define fungal species boundaries in the future. The other papers in this special issue deal with fungal speciation in Ascomycota, Dothideomycetes, Basidiomycota, basal fungi, lichen-forming fungi, plant pathogenic fungi, and yeasts.

这是真菌多样性特刊的开篇论文，它整理了有关定义物种的数据。长期以来，定义和识别物种一直是一个有争议的问题。自从达尔文提出物种起源以来，已经提出了 30 多种物种标准并用于定义物种边界。近年来，基于多个位点的系统发育分析已被广泛用作定义物种边界的方法。然而，只有少数真菌学家意识到系统发育物种标准会掩盖真菌群体之间的不一致，导致物种边界定义不准确。在当前的审查中，我们讨论了物种识别标准、如何以及在何处应用这些标准以及它们的局限性和衍生的替代方案。为了界定真菌物种，作者不仅需要考虑系统发育和表型的一致性，以及导致真菌物种形成和随后多样化的事件发生的时间。表型多样化和趋同真菌进化率的变化使得难以建立通用的物种识别标准。最佳实践只能在每个真菌组的上下文中定义。在这篇综述中，我们提供了一套指导方针，鼓励采用综合分类方法进行物种划界，未来可用于定义真菌物种边界。本期特刊中的其他论文涉及真菌物种形成 最佳实践只能在每个真菌组的上下文中定义。在这篇综述中，我们提供了一套指导方针，鼓励采用综合分类方法进行物种划界，未来可用于定义真菌物种边界。本期特刊中的其他论文涉及真菌物种形成 最佳实践只能在每个真菌组的上下文中定义。在这篇综述中，我们提供了一套指导方针，鼓励采用综合分类方法进行物种划界，未来可用于定义真菌物种边界。本期特刊中的其他论文涉及真菌物种形成子囊菌门、链球菌门、担子菌门、基底真菌、形成地衣的真菌、植物病​​原真菌和酵母菌。