Sexual reproduction is the basic way to form high genetic diversity and it is beneficial in evolution and speciation of fungi. The global diversity of teleomorphic species in Ascomycota has not been estimated. This paper estimates the species number for sexual ascomycetes based on five different estimation approaches, viz. by numbers of described fungi, by fungus:substrate ratio, by ecological distribution, by meta-DNA barcoding or culture-independent studies and by previous estimates of species in Ascomycota. The assumptions were made with the currently most accepted, “2.2–3.8 million” species estimate and results of previous studies concluding that 90% of the described ascomycetes reproduce sexually. The Catalogue of Life, Species Fungorum and published research were used for data procurement. The average value of teleomorphic species in Ascomycota from all methods is 1.86 million, ranging from 1.37 to 2.56 million. However, only around 83,000 teleomorphic species have been described in Ascomycota and deposited in data repositories. The ratio between described teleomorphic ascomycetes to predicted teleomorphic ascomycetes is 1:22. Therefore, where are the undiscovered teleomorphic ascomycetes? The undescribed species are no doubt to be found in biodiversity hot spots, poorly-studied areas and species complexes. Other poorly studied niches include extremophiles, lichenicolous fungi, human pathogens, marine fungi, and fungicolous fungi. Undescribed species are present in unexamined collections in specimen repositories or incompletely described earlier species. Nomenclatural issues, such as the use of separate names for teleomorph and anamorphs, synonyms, conspecific names, illegitimate and invalid names also affect the number of described species. Interspecies introgression results in new species, while species numbers are reduced by extinctions.

有性繁殖是形成高度遗传多样性的基本方式，有利于真菌的进化和物种形成。子囊菌门有性形物种的全球多样性尚未估计。本文基于五种不同的估计方法估计了有性子囊菌的物种数，即。通过所描述真菌的数量、通过真菌与底物的比例、通过生态分布、通过元 DNA 条形码或独立于培养物的研究以及通过先前对子囊菌门物种的估计。这些假设是根据目前最被接受的“2.2-380 万”物种估计值和之前研究的结果得出的，其中 90% 的所描述的子囊菌是有性繁殖的。生命目录、真菌物种和已发表的研究用于数据采购。所有方法得到的子囊菌有性体物种的平均值为186万个，范围为1.37至256万个。然而，子囊菌门中只有大约 83,000 个有性形态物种被描述并存放在数据存储库中。所述有形子囊菌与预测有形子囊菌之间的比例为1:22。那么，未被发现的有形子囊菌在哪里呢？毫无疑问，未描述的物种存在于生物多样性热点、研究较少的地区和物种复合体中。其他研究不足的生态位包括极端微生物、地衣真菌、人类病原体、海洋真菌和真菌真菌。未描述的物种存在于标本库中未经检查的收藏中或未完全描述的早期物种中。命名法问题，例如对有性型和无性型使用单独的名称、同义词、同种名称、非法和无效名称也会影响所描述物种的数量。种间渗入会产生新物种，而物种数量则因灭绝而减少。