ABSTRACT In tropical and subtropical rainforests, vegetative fungal rhizomorphs from the Marasmiineae are routinely used as construction material in bird nests. Because rhizomorphs seldom produce mushrooms within nests, the fungal species involved remain largely unknown. In turn, this limitation has prevented us from resolving broader questions such as whether specific fungal species are selected by birds for different functional roles (i.e., attachment, or parasite control). To fill some of these gaps, we collected 74 rhizomorph-containing bird nests from the Neo- and Afrotropics and used nuc rDNA internal transcribed spacer ITS1-5.8S-ITS2 (ITS) sequences to discriminate between rhizomorph-forming species. In total we recovered 25 Marasmiineae species used by birds in nest construction, none of which were shared between the Neotropics and the Afrotropics. We also collected Marasmiineae basidiomes in the vicinity of nests and used ITS sequences to match these sporulating morphs with nest rhizomorphs for nine species. Basidiomes from an additional five species were found fruiting from rhizomorphs incorporated within bird nests. Finally, an additional six species were putatively identified based on publicly available sequence data. Rhizomorphs of five species were found to be utilized almost exclusively as lining material in nests. Lining material comes in direct contact with nestlings and is hypothesized to play a role in parasite control. Rhizomorphs from 10 species were used to attach and anchor nests to substrates; we matched six of those to fruiting litter trap-forming species collected in the understory. Litter traps hold large quantities of fallen litter material, suggesting that birds may preferentially use rhizomorphs that are adapted to bearing heavy loads for nest attachment. Finally, we describe two species of Marasmius—M. neocrinis-equi, sp. nov., and M. nidus-avis, sp. nov.—that are commonly found associated with bird nests and show that rhizomorph production is common across the genus.

中文翻译：

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鸟巢中的 Marasmioid 根状茎：物种多样性、功能特异性和来自热带的新物种

摘要在热带和亚热带雨林中，来自 Marasmiineae 的营养真菌根状体通常用作鸟巢的建筑材料。由于根状菌很少在巢内产生蘑菇，因此所涉及的真菌种类在很大程度上仍然未知。反过来，这种限制使我们无法解决更广泛的问题，例如鸟类是否选择特定的真菌物种以发挥不同的功能作用（即附着或寄生虫控制）。为了填补其中的一些空白，我们从新热带和非洲热带地区收集了 74 个含有根状茎的燕窝，并使用 nuc rDNA 内部转录间隔 ITS1-5.8S-ITS2 (ITS) 序列来区分根状茎形成物种。我们总共回收了 25 种鸟类在筑巢时使用的 Marasmiineae 物种，新热带地区和非洲热带地区都没有共享这些。我们还收集了巢附近的 Marasmiineae basidiomes，并使用 ITS 序列将这些孢子形成的形态与 9 个物种的巢根形进行了匹配。来自另外五个物种的担子组被发现从鸟巢中的根状茎中结出果实。最后，根据公开可用的序列数据推定鉴定了另外六个物种。发现五个物种的根状茎几乎完全被用作巢穴的衬里材料。衬里材料与雏鸟直接接触，并被假设在寄生虫控制中发挥作用。来自 10 个物种的根状茎被用来将巢附着和锚定在基质上；我们将其中的六个与在林下收集的结果垃圾陷阱形成物种相匹配。垫料陷阱可容纳大量掉落的垫料，这表明鸟类可能会优先使用适合承受重负荷的根状茎来附着巢穴。最后，我们描述了两种 Marasmius——M. Neocrinis-equi, sp. 11 月，和 M. nidus-avis，sp。nov.-通常发现与燕窝有关，并表明根状茎的产生在整个属中都很常见。