Real Jardín Botánico, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain.
Departamento de Biología (Botánica), Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, Darwin 2, 28049 Madrid, Spain.
Protist. 2021 Apr;172(2):125805. doi: 10.1016/j.protis.2021.125805. Epub 2021 Mar 26.
Myxomycetes constitute one of the major lineages within the supergroup Amoebozoa. At the end of their life cycles, most myxomycetes produce spore-bearing fruiting bodies, in which additional structures develop, like the capillitium, a system of sterile filaments intermingled with the spores. The capillitium is a relevant structure in the taxonomy of the order Trichiales, the target group in this study. However, the introduction of molecular phylogenies in Myxomycetes systematics is challenging our comprehension of this structure. We studied the capillitium of 25 species representing nine Trichiales genera, with both scanning and transmission electron microscopy. In this order, the capillitium showed higher diversity than so far recognized. Thus, we distinguished and described five capillitium types and two subtypes based on the presence or absence of a lumen and the wall ultrastructure. These types followed the evolutionary history reported in recent phylogenies, although not all of them defined monophyletic groups. Besides, the spiral ornamentation, which most taxonomists considered to have appeared once, occurred in three different capillitium types. The ultrastructural approaches in Myxomycetes systematics enable the reconsideration of their morphological features in the new phylogenetic scenario.
粘菌门是变形体超群中的一个主要分支。在生命周期末期，大多数粘菌会产生具有孢子的子实体，在其中会发育出其他结构，如毛基体，这是一种与孢子交织在一起的无菌细丝系统。毛基体是研究目标—— Trichiales 目分类学中的一个重要结构。然而，分子系统发育学在粘菌系统学中的引入，正在挑战我们对该结构的理解。我们使用扫描和透射电子显微镜研究了代表九个 Trichiales 属的 25 种粘菌的毛基体。在这个目中，毛基体显示出比以前认识到的更高的多样性。因此，我们根据是否存在腔和壁的超微结构，区分并描述了五种毛基体类型和两种亚型。这些类型遵循了最近系统发育研究报告的进化历史，尽管并非所有类型都定义了单系群。此外，大多数分类学家认为只出现过一次的螺旋纹饰出现在三种不同的毛基体类型中。粘菌系统发育学中的超微结构方法使我们能够在新的系统发育情景中重新考虑它们的形态特征。
