The biodiversity of filamentous fungi and their ecological relationships in the context of decaying Araucaria angustifolia (an endangered conifer) substrates are still mostly unknown. The present study aimed to investigate the diversity of saprotrophic filamentous fungi, based on morphological identification, associated with A. angustifolia, in addition to assessing possible saprobic/plant affinity relationship, and verifying whether the study areas and substrates affect the composition of the mycobiota. A total of 5000 substrates (decaying needles and twigs) were collected during five expeditions (2014/2015) to two areas: São Francisco de Paula National Forest (FLONA-SFP) and São Joaquim National Park (PARNA-SJ), Brazil. A total of 135 species distributed among 85 genera, 40 families, nine classes, 24 orders, three subphyla, and two phyla were identified. One new genus and five new species that were previously described, and six rare species and five species with affinity for A. angustifolia were also recorded. The twigs showed a community of fungi with greater richness and dominance. Conversely, the values of abundance, Simpson’s diversity index, and evenness were lower than those determined for needles. In terms of the study areas, FLONA-SFP showed higher values of richness, abundance, Simpson’s diversity index, and evenness than PARNA-SJ. Principal coordinate analysis and similarity percentage analysis showed the influence of both substrate factors and areas in the composition of the fungal communities. The presence of new, rare, and affinity-related species reinforces the study of fungi in the context of the conservation of this conifer, as these species are threatened by co-extinction.

在腐烂的南洋杉（一种濒临灭绝的针叶树）基质的背景下，丝状真菌的生物多样性及其生态关系仍然大多未知。本研究旨在基于形态学鉴定研究与A. angustifolia相关的腐养丝状真菌的多样性，除了评估可能的腐生菌/植物亲和力关系，并验证研究区域和底物是否影响真菌群的组成。在巴西的圣弗朗西斯科德保拉国家森林 (FLONA-SFP) 和圣若阿金国家公园 (PARNA-SJ) 的五次探险 (2014/2015) 期间，总共收集了 5000 个基质（腐烂的针和树枝）。共鉴定出135种，分布于85属40科9纲24目3亚门2门。先前描述的1个新属和5个新种，以及6个稀有种和5个对A. angustifolia有亲和力的种也被记录了。树枝显示出一个真菌群落，具有更大的丰富性和优势。相反，丰度、辛普森多样性指数和均匀度的值低于针的确定值。就研究区域而言，FLONA-SFP在丰富度、丰度、辛普森多样性指数和均匀度上均高于PARNA-SJ。主坐标分析和相似性百分比分析显示了底物因素和区域对真菌群落组成的影响。新的、稀有的和亲和相关物种的存在加强了在保护这种针叶树的背景下对真菌的研究，因为这些物种受到共灭绝的威胁。