红菇属变红乳菇亚属的乳汁常变为红色,变黄的乳汁较为少见.在中国中南部亚热带壳斗科林下发现了一个乳汁迅速变黄色的物种.这是首次在中国发现的变红乳菇亚属中乳汁变黄的物种,其独特的乳汁、褐色的菌盖、稀疏的菌褶和大的具极高翼状纹饰的孢子能将其与其他已知种区分开来,在此将其描述为新种,黄美乳菇L.mirus.本研究提供了该新种的DNA条形码ITS-LSU区域和形态特征描述,并将其与其他乳汁变黄的物种如马来西亚的L.flavorosescens和L.pallidior进行了对比.这一发现为证实中国乳菇属的亚热带-热带地区与亚洲热带地区的亲缘增加了新的证据.“,”Species of Lactarius subg.Plinthogalus have latex often changing to reddish.Yellowing latex is relatively rare.Lactarius mirus,a species with white latex instantly changing to bright yellow was found from subtropical fagaceous forests in central-southern China.This is the first report of species with yellowing latex in L.subg.Plinthogalus in China.The unique latex,the brown pileus,distant lamellae and big globose spores with high winged ornamentation distinguish it from all other known species,and therefore,it is described as a new species.DNA barcode nrlTS-LSU region and morphological description and illustrations are provided.Morphological differences between L.mirus and the other species with yellowing latex,e.g.Malaysian L.flavorosescens and L.pallidior are discussed.The finding of this species adds new evidence showing biogeographically subtropical and tropical affinity of Lactarius in China.