University of Maryland, Department of Plant Science and Landscape Architecture, College Park, MD 20742, USA.
Mycologia. 2012 Nov-Dec;104(6):1325-50. doi: 10.3852/12-055. Epub 2012 Jul 9.
Thelonectria is a recently established genus of common and ubiquitous fungi on woody hosts, previously placed in the genus Neonectria. Thelonectria coronata and T. veuillotiana occur sympatrically in tropical, subtropical and temperate regions. Previous taxonomic studies including T. coronata and T. veuillotiana suggested these fungi could represent species complexes; however, the morphological features used to define species exhibited few differences useful for testing this hypothesis. To assess the status of T. coronata and T. veuillotiana, phylogenetic analyses of six genomic regions were combined with a morphological examination of specimens. A multi-gene phylogeny reconstructed with maximum parsimony, maximum likelihood and Bayesian approaches identified five phylogenetic groups in T. coronata and six in T. veuillotiana. As is common for cryptic species, unequivocal diagnostic morphological characters could not be identified; however, average values of morphological traits correspond to the phylogenetic groups. An increased number of non-synonymous/synonymous substitutions in the β-tubu-lin gene and a decreased or absent production of conidia were detected within the T. coronata complex, possibly indicating the homothallic nature of these isolates. T. coronata and T. veuillotiana and related species are described and illustrated here; a dichotomous key to all species is provided.
冠突离蠕孢是一个新近建立的真菌属，常见于木质宿主，先前被归入 Neocectria 属。冠突离蠕孢（T. coronata）和韦氏离蠕孢（T. veuillotiana）在热带、亚热带和温带地区共生。先前的分类学研究包括 T. coronata 和 T. veuillotiana，表明这些真菌可能代表物种复合体；然而，用于定义物种的形态特征差异很小，难以验证这一假设。为了评估 T. coronata 和 T. veuillotiana 的状况，我们对 6 个基因组区域进行了系统发育分析，并结合对标本的形态学检查。最大简约法、最大似然法和贝叶斯法重建的多基因系统发育树确定了 T. coronata 中的 5 个系统发育群和 T. veuillotiana 中的 6 个系统发育群。与常见的隐种一样，无法确定明确的诊断形态特征；然而，形态特征的平均值与系统发育群相对应。在 T. coronata 复合体中检测到 β-微管蛋白基因中非同义/同义替换的增加和分生孢子产生的减少或缺失，这可能表明这些分离物的同宗结合性质。本文描述并图示了 T. coronata 和 T. veuillotiana 及其相关种；并提供了一个所有种的二歧检索表。
