Tsui Clement K M, Sivichai Somsak, Berbee Mary L
Department of Botany, University of British Columbia, Vancouver, Canada.
Mycologia. 2006 Jan-Feb;98(1):94-104. doi: 10.3852/mycologia.98.1.94.
Three genera of asexual, helical-spored fungi, Helicoma, Helicomyces and Helicosporium traditionally have been differentiated by the morphology of their conidia and conidiophores. In this paper we assessed their phylogenetic relationships from ribosomal sequences from ITS, 5.8S and partial LSU regions using maximum parsimony, maximum likelihood and Bayesian analysis. Forty-five isolates from the three genera were closely related and were within the teleomorphic genus Tubeufia sensu Barr (Tubeufiaceae, Ascomycota). Most of the species could be placed in one of the seven clades that each received 78% or greater bootstrap support. However none of the anamorphic genera were monophyletic and all but one of the clades contained species from more than one genus. The 15 isolates of Helicoma were scattered through the phylogeny and appeared in five of the clades. None of the four sections within the genus were monophyletic, although species from Helicoma sect. helicoma were concentrated in Clade A. The Helicosporium species also appeared in five clades. The four Helicomyces species were distributed among three clades. Most of the clades supported by sequence data lacked unifying morphological characters. Traditional characters such as the thickness of the conidial filament and whether conidiophores were conspicuous or reduced proved to be poor predictors of phylogenetic relationships. However some combinations of characters including conidium colour and the presence of lateral, tooth-like conidiogenous cells did appear to be predictive of genetic relationships.
无性、螺旋状孢子真菌的三个属，即Helicoma、Helicomyces和Helicosporium，传统上是通过它们的分生孢子和分生孢子梗的形态来区分的。在本文中，我们使用最大简约法、最大似然法和贝叶斯分析，从ITS、5.8S和部分LSU区域的核糖体序列评估了它们的系统发育关系。来自这三个属的45个分离株密切相关，属于有性型属Tubeufia sensu Barr（Tubeufiaceae，子囊菌门）。大多数物种可以归入七个分支中的一个，每个分支都获得了78%或更高的自展支持。然而，这些无性型属都不是单系的，除了一个分支外，所有分支都包含来自多个属的物种。15个Helicoma分离株分散在系统发育树中，出现在五个分支中。该属内的四个组都不是单系的，尽管Helicoma组helicoma的物种集中在分支A中。Helicosporium物种也出现在五个分支中。四个Helicomyces物种分布在三个分支中。序列数据支持的大多数分支缺乏统一的形态特征。传统特征，如分生孢子丝的厚度以及分生孢子梗是否明显或退化，被证明是系统发育关系的不良预测指标。然而，包括分生孢子颜色和侧面齿状产孢细胞的存在等一些特征组合似乎确实可以预测遗传关系。
