Sato Hirotoshi, Hattori Tsutomu
Center for Ecological Research, Kyoto University, 509-3, 2-chome, Hirano, Otsu, Shiga, 520-2113, Japan.
Forestry and Forest Products Research Institute, Matsunosato 1, Tsukuba, Ibaraki, 305-8687, Japan.
PLoS One. 2015 Jun 17;10(6):e0128184. doi: 10.1371/journal.pone.0128184. eCollection 2015.
We describe and illustrate two new species of Boletellus section Boletellus, B. aurocontextus sp. nov. and B. areolatus sp. nov., which are generally assumed to be B. emodensis. In this study, we reconstructed separate molecular phylogenetic trees of section Boletellus using the nucleotide sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA, the largest subunit (RPB1) and the second-largest subunit (RPB2) of nuclear RNA polymerase II gene and mitochondrial cytochrome oxidase subunit 3 (cox3) gene. We also examined the morphologies of B. emodensis sensu lato (s.l.) and other related species for comparison. The molecular phylogenetic tree inferred from the sequences of nuclear DNA (ITS, and combined dataset of RPB1 and RPB2) indicated that three genetically and phylogenetically well-separated lineages were present within B. emodensis s.l. These three lineages were also distinguished on the basis of the molecular phylogenetic tree constructed using the sequences of mitochondrial DNA (cox3), suggesting distinct cytonuclear disequilibria (i.e., evidence of reproductive isolation) among these lineages. Therefore, these three lineages can be treated as independent species: B. aurocontextus, B. areolatus, and B. emodensis. Boletellus aurocontextus and B. areolatus are also distinct from B. emodensis by the macro- and microscopic morphologies. Boletellus aurocontextus is characterized by a pileus with bright yellow to lemon yellow context, which can be observed through a gap in the scales, and basidiospores with relatively large length (mean spore length, 21.4 μm; quotient of spore length and width, 2.51). In contrast, B. areolatus is characterized by a pileus with floccose to appressed thin scaly patches, a stipe with pallid or pale cream color at the upper half, and basidiospores with relatively small length (mean spore length, 16.5 μm; quotient of spore length and width, 1.80).
我们描述并图示了牛肝菌属牛肝菌组的两个新物种，即金黄菌幕牛肝菌（Boletellus aurocontextus sp. nov.）和网纹牛肝菌（Boletellus areolatus sp. nov.），它们通常被认为是埃默德牛肝菌（Boletellus emodensis）。在本研究中，我们利用核糖体DNA的内转录间隔区（ITS）区域、核RNA聚合酶II基因的最大亚基（RPB1）和第二大亚基（RPB2）以及线粒体细胞色素氧化酶亚基3（cox3）基因的核苷酸序列，重建了牛肝菌组各自的分子系统发育树。我们还检查了广义埃默德牛肝菌（Boletellus emodensis sensu lato，s.l.）及其他相关物种的形态以作比较。从核DNA序列（ITS以及RPB1和RPB2的组合数据集）推断出的分子系统发育树表明，广义埃默德牛肝菌内存在三个在遗传和系统发育上明显分开的谱系。基于使用线粒体DNA序列（cox3）构建的分子系统发育树，这三个谱系也有区别，表明这些谱系之间存在明显的细胞核与细胞质失衡（即生殖隔离的证据）。因此，这三个谱系可视为独立的物种：金黄菌幕牛肝菌、网纹牛肝菌和埃默德牛肝菌。金黄菌幕牛肝菌和网纹牛肝菌在宏观和微观形态上也与埃默德牛肝菌不同。金黄菌幕牛肝菌的特征在于菌盖具有亮黄色至柠檬黄色的菌肉，透过鳞片的间隙可以观察到，担孢子长度相对较大（平均孢子长度为21.4μm；孢子长度与宽度的商为2.51）。相比之下，网纹牛肝菌的特征在于菌盖具有絮状至紧贴的薄鳞片斑块，菌柄上半部为灰白色或浅奶油色，担孢子长度相对较小（平均孢子长度为16.5μm；孢子长度与宽度的商为1.80）。
