ABSTRACT

Species of Russula are ubiquitous members of ectomycorrhizal fungal communities in tropical ecosystems. However, an important part of the total tropical diversity of this genus and its biogeographic patterns is unknown due to the lack of studies on Russula in tropical ecosystems. We combined molecular, morphological, ecological, and biogeographic data to elaborate concepts for two new subspecies of R. floriformis (subsection Substriatinae). Russula floriformis subsp. floriformis and R. floriformis subsp. symphoniae are described as new from montane forest dominated by Quercus and/or Oreomunnea (Fagales) from Colombia and Panama, respectively. Phylogenies were constructed using nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS), D1–D2 domains of nuc 28S rDNA (28S), and partial regions of the second largest subunit of RNA polymerase II (rpb2) and translation elongation factor 1-alpha (tef1). Similar environmental conditions, similar morphology, and an ITS sequence similarity higher than 99% with only three different positions indicate that these two subspecies are closely related. Detailed observations of microscopic structures and analyses of further DNA loci, however, revealed morphological and molecular characteristics that allow distinguishing the two subspecies of R. floriformis. Spatial distribution and phylogenetic proximity of the two Russula subspecies and their ectomycorrhizal hosts, i.e., species of Quercus, suggest that their diversification is a result of comigration, adaptation, and geographic isolation along the Isthmus of Panama during the Pliocene and Pleistocene.

摘要

Russula物种是热带生态系统中外生菌根真菌群落中无处不在的成员。然而，由于缺乏对热带生态系统中红菇的研究，该属热带多样性的重要组成部分及其生物地理模式尚不清楚。我们结合分子、形态学、生态学和生物地理数据，详细阐述了两个新亚种R. floriformis（Substriatinae 小节）的概念。Russula floriformis subsp。floriformis和R. floriformis subsp。symphoniae被描述为来自以Quercus和/或Oreomunnea为主的山地森林的新作品(Fagales) 分别来自哥伦比亚和巴拿马。使用 nuc rDNA 内部转录间隔区 ITS1-5.8S-ITS2 (ITS)、nuc 28S rDNA (28S) 的 D1-D2 结构域以及 RNA 聚合酶 II ( rpb2 ) 和翻译延伸的第二大亚基的部分区域构建系统发育因子 1-alpha ( tef1 )。相似的环境条件、相似的形态以及仅三个不同位置的 ITS 序列相似度高于 99% 表明这两个亚种密切相关。然而，对微观结构的详细观察和进一步 DNA 基因座的分析揭示了形态和分子特征，可以区分R. floriformis的两个亚种. 两个红菇亚种及其外生菌根宿主（即栎属）的空间分布和系统发育接近度表明，它们的多样化是上新世和更新世沿巴拿马地峡迁徙、适应和地理隔离的结果。