Molecular phylogenetic analyses and micromorphology reveal placement of the enigmatic tropical discomycete Polydiscidium in Sclerococcum (Sclerococcales, Eurotiomycetes)
Molecular phylogenetic analyses and micromorphology reveal placement of the enigmatic tropical discomycete Polydiscidium in Sclerococcum (Sclerococcales, Eurotiomycetes)
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DOI：
10.1080/00275514.2022.2048625
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发表时间：
2022-05
期刊：
影响因子：
2.8
通讯作者：
D. Haelewaters;Jeffery K. Stallman;T. Henkel;M. C. Aime
中科院分区：
文献类型：
--
作者：
D. Haelewaters;Jeffery K. Stallman;T. Henkel;M. C. Aime
摘要多囊菌属是子囊菌门中一个神秘的单型属，在文献中的报道很少。形态独特的Polyacridium martynii生长在枯木上，形成由厚，黑色，凝胶状的体细胞组织组成的复合子囊，从共同的基部分支出来。分枝上有多个孢囊，大多数朝向顶端，由8孢子的子囊和嵌在凝胶状基质中的侧丝组成，凝胶状基质在梅尔策试剂中变蓝。该物种以前只在圭亚那（正模标本）、特立尼达和刚果民主共和国的三个标本中发现，并且没有序列存在。由于其独特的形态，Polyacridium的分类学亲缘关系一直存在争议，不同的作者将其置于Helotiaceae，Leotiaceae或Leotiomycetes incertae sedis中。在圭亚那和喀麦隆的长期野外工作导致该物种的最近收集使我们重新审视了这种真菌的形态和系统发育位置。将新生成的马蒂毕赤酵母序列添加到子囊菌全六位点数据集中。由此产生的系统发育表明Polyacidium是Sclerocococcales（Eurotiomycetes）的成员。其次，通过18S、ITS、28S、mtSSU四位点系统发育分析，初步揭示了该属与硬球菌属的同源性。本文提出了一个新的组合，即Sclerococcum martynii。其微形态特征与硬球菌属一致，包括由淀粉样凝胶帽的子囊和具隔的棕色子囊孢子组成的凝胶状子实层。另外两个种的新组合被提出：Sclerococcum chiangraiensis和S。梭形。最后，Daclidococcales被认为是Sclerococcales的后来的同义词。
ABSTRACT Polydiscidium is an enigmatic, monotypic, and rarely reported genus of Ascomycota of uncertain placement. The morphologically unique Polydiscidium martynii grows on dead wood and forms compound ascomata composed of thick, black, gelatinous somatic tissue that branches out from a common base. Multiple apothecia are located on the branches, mostly toward the tips, and are composed of 8-spored asci and paraphyses embedded in a gelatinous matrix that turns blue in Melzer’s reagent. The species was previously known from only three collections from Guyana (holotype), Trinidad, and the Democratic Republic of the Congo and no sequences exist. Due to its peculiar morphology, taxonomic affinities of Polydiscidium have been debated, with different authors having placed it in Helotiaceae, Leotiaceae, or Leotiomycetes incertae sedis. Recent collections of this species resulting from long-term field work in Guyana and Cameroon led us to revisit the morphology and phylogenetic position of this fungus. Newly generated sequences of P. martynii were added to an Ascomycota-wide six-locus data set. The resulting phylogeny showed Polydiscidium to be a member of order Sclerococcales (Eurotiomycetes). Next, a four-locus (18S, ITS, 28S, mtSSU) phylogenetic reconstruction revealed that Polydiscidium is congeneric with Sclerococcum. A new combination is proposed for this species, Sclerococcum martynii. Micromorphological features, including the gelatinous hymenium composed of asci with amyloid gel cap and septate brown ascospores, are in agreement with Sclerococcum. New combinations are proposed for two additional species: Sclerococcum chiangraiensis and S. fusiformis. Finally, Dactylosporales is considered a later synonym of Sclerococcales.