Spores are the dispersal and reproductive units in Myxomycetes, and their ornamentation, usually at the light microscopy resolution limit, is taxonomically meaningful. Here, we analyze with scanning and transmission electron microscopy the spore ultrastructural features in Trichiales, one of the most morphologically diverse orders. In Trichiales, the spore wall consists of two layers, an outer one, including the ornamentation, and an inner layer subdivided into two sections. The diversity of ornamental elements includes verrucae, bacula, pila, muri, and cristae, the two latter creating reticulate patterns. Each of these elements defines a broadly recognized ornamentation type except cristae, from which we differentiate for the first time the cristate reticulate and patched subtypes. Besides, our results point out a previous incorrect classification of the spores of the species Trichia decipiens and T. scabra. Advances in Trichiales phylogeny showed that the capillitium ornamental elements, such as the spirals, do not reflect phylogenetic relationships among the species. The same seems to apply to some of spore ornamentation types, e.g., baculate. Consequently, we may consider the need to combine multiple characters, like the spore and capillitium ornamentation, so that Trichiales systematics better reflect the still cryptic phylogenetic affinities.

孢子是粘菌纲中的分散和繁殖单位，它们的装饰通常在光学显微镜分辨率极限下具有分类学意义。在这里，我们用扫描和透射电子显微镜分析了 Trichiales 中的孢子超微结构特征，这是形态学上最多样化的目之一。在 Trichiales 中，孢子壁由两层组成，外层包括装饰，内层细分为两部分。装饰元素的多样性包括疣、芽、皮拉、木里和嵴，后两者形成网状图案。这些元素中的每一个都定义了一种广泛认可的装饰类型，除了嵴，我们第一次从中区分了嵴网状和斑纹亚型。除了，Trichia decipiens和T . 斯卡布拉。Trichiales 系统发育的进展表明，毛状花序装饰元素，如螺旋，不反映物种之间的系统发育关系。这似乎也适用于一些孢子装饰类型，例如，杆状。因此，我们可能会考虑需要结合多个特征，如孢子和毛状体装饰，以便 Trichiales 系统学更好地反映仍然神秘的系统发育亲缘关系。