ABSTRACT

A new nivicolous myxomycete is described as a result of a comprehensive study of Didymium nivicola collections from the entire range of its occurrence. Statistical analysis of 12 morphological characters, phylogenetic analyses of nuc 18S rDNA and elongation factor 1-alpha gene (EF1A), and a delimitation method (automatic barcode gap diversity) have been applied to corroborate the identity of the new species. A preliminary morphological analysis of D. nivicola revealed high variability of South American populations where four types of spore ornamentation were noted. However, results of molecular study and statistical analysis of morphological characters did not support recognition of these four forms but the distinction of two morphotypes. Consequently, two species have been recognized: D. nivicola and the newly proposed D. pseudonivicola. The new species can be distinguished from D. nivicola by distinctly larger and mostly plasmodiocarpic sporophores, which are scattered to gregarious, paler spores, and by the paler, more delicate and more elastic capillitium. Spore ornamentation of D. pseudonivicola is uniform and can be described as distinctly spiny (pilate under scanning electron microscope [SEM]), whereas those of D. nivicola is more variable, where spines (pilae under SEM) are delicate, distinct, or conspicuous. Additionally, whereas D. nivicola is a species distributed worldwide, D. pseudonivicola occurs only in the austral Andes of Argentina and Chile.

摘要

一种新的 nivicolous myxomycete 被描述为对Didymium nivicola集合的全面研究的结果，该集合来自其发生的整个范围。已应用 12 个形态特征的统计分析、nuc 18S rDNA 和延伸因子 1-α 基因 ( EF1A ) 的系统发育分析以及定界方法（自动条形码间隙多样性）来证实新物种的身份。D. nivicola的初步形态分析揭示了南美种群的高度可变性，其中注意到四种孢子装饰。然而，分子研究和形态特征的统计分析结果并不支持这四种形式的识别，而是两种形态类型的区分。因此，已识别出两个物种：D. nivicola和新提出的D. pseudonivicola。新种与D. nivicola的区别在于明显较大且大部分为等生果核的孢子体，这些孢子散布成群居的、颜色较浅的孢子，以及较浅、更细腻和更有弹性的毛细血管。D. pseudonivicola的孢子纹饰是均匀的，可以被描述为明显多刺（扫描电子显微镜下 [SEM] 下的普拉提），而D. nivicola的那些变化更大，其中刺（SEM 下的 pilae）是精致的、明显的或明显的。此外，虽然D. nivicola是一种分布于世界各地的物种，但D. pseudonivicola仅出现在阿根廷和智利的安第斯山脉南部。