ABSTRACT Ambrosia beetles farm fungal cultivars (ambrosia fungi) and carry propagules of the fungal mutualists in storage organs called mycangia, which occur in various body parts and vary greatly in size and complexity. The evolution of ambrosia fungi is closely tied to the evolution and development of the mycangia that carry them. The understudied ambrosia beetle tribe Xyloterini included lineages with uncharacterized ambrosia fungi and mycangia, which presented an opportunity to test whether developments of different mycangium types in a single ambrosia beetle lineage correspond with concomitant diversity in their fungal mutualists. We collected representatives of all three Xyloterini genera (Trypodendron, Indocryphalus, and Xyloterinus politus) and characterized their ambrosia fungi in pure culture and by DNA sequencing. The prothoracic mycangia of seven Trypodendron species all yielded Phialophoropsis (Microascales) ambrosia fungi, including three new species, although these relationships were not all species specific. Indocryphalus mycangia are characterized for the first time in the Asian I. pubipennis. They comprise triangular prothoracic cavities substantially smaller than those of Trypodendron and unexpectedly carry an undescribed species of Toshionella (Microascales), which are otherwise ambrosia fungi of Asian Scolytoplatypus (Scolytoplatypodini). Xyloterinus politus has two different mycangia, each with a different ambrosia fungus: Raffaelea cf. canadensis RNC5 (Ophiostomatales) in oral mycangia of both sexes and Kaarikia abrahamsonii (Sordariomycetes, genus incertae sedis with affinity for Distoseptisporaceae), a new genus and species unrelated to other known ambrosia fungi, in shallow prothoracic mycangia of females. In addition to their highly adapted mycangial mutualists, Trypodendron and X. politus harbor a surprising diversity of facultative symbionts in their galleries, including Raffaelea. A diversity of ambrosia fungi and mycangia suggest multiple ancestral cultivar captures or switches in the history of tribe Xyloterini, each associated with unique adaptations in mycangium anatomy. This further supports the theory that developments of novel mycangium types are critical events in the evolution of ambrosia beetles and their coadapted fungal mutualists.

中文翻译：

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甘草真菌的四种菌丝类型和四种属表明甘草甲虫部落 Xyloterini 真菌养殖的复杂历史

摘要 豚草甲虫养殖真菌栽培品种（豚草真菌），并在称为菌丝体的储存器官中携带真菌共生体的繁殖体，菌体发生在身体的各个部位，大小和复杂性差异很大。豚草真菌的进化与携带它们的菌体的进化和发育密切相关。未充分研究的甘草甲虫部落 Xyloterini 包括具有未表征的甘草真菌和菌丝体的谱系，这提供了一个机会来测试单个甘草甲虫谱系中不同菌丝类型的发展是否与其真菌共生体中伴随的多样性相对应。我们收集了所有三个 Xyloterini 属（Trypodendron、Indocryphalus 和 Xyloterinus politus）的代表，并在纯培养和 DNA 测序中表征了它们的甘草真菌。七个 Trypodendron 物种的前胸肌层都产生了 Phialophoropsis (Microascales) ambrosia 真菌，包括三个新物种，尽管这些关系并非所有物种都具有特异性。Indocryphalus mycangia 首次在亚洲 I. pubipennis 中得到表征。它们包含比 Trypodendron 小得多的三角形前胸腔，并且出人意料地携带一种未描述的 Toshionella (Microascales)，否则它们是亚洲 Scolytoplatypus (Scolytoplatypodini) 的甘草真菌。Xyloterinus politus 有两种不同的菌丝体，每种菌体都有不同的豚草真菌：Raffaelea cf. canadensis RNC5 (Ophiostomatales) 在两性和 Kaarikia abrahamsonii (Sordariomycetes, genus incertae sedis with Distoseptisporaceae) 的口腔菌丝体中，一种新的属和种，与其他已知的豚草真菌无关，位于雌性的浅前胸肌内。除了高度适应的菌丝共生体外，Trypodendron 和 X. politus 在它们的画廊中还拥有令人惊讶的兼性共生体多样性，包括 Raffaelea。仙人掌真菌和菌丝体的多样性表明，Xyloterini 部落历史上有多个祖先品种的捕获或转换，每一个都与菌丝体解剖结构的独特适应性有关。这进一步支持了以下理论，即新型菌丝体类型的发展是豚草甲虫及其共同适应的真菌共生体进化过程中的关键事件。politus 在他们的画廊中拥有令人惊讶的兼性共生体多样性，包括 Raffaelea。仙人掌真菌和菌丝体的多样性表明，Xyloterini 部落历史上有多个祖先栽培品种的捕获或转换，每一个都与菌丝体解剖结构的独特适应性有关。这进一步支持了以下理论，即新型菌丝体类型的发展是豚草甲虫及其共同适应的真菌共生体进化过程中的关键事件。politus 在他们的画廊中拥有令人惊讶的兼性共生体多样性，包括 Raffaelea。仙人掌真菌和菌丝体的多样性表明，Xyloterini 部落历史上有多个祖先栽培品种的捕获或转换，每一个都与菌丝体解剖结构的独特适应性有关。这进一步支持了以下理论，即新型菌丝体类型的发展是豚草甲虫及其共同适应的真菌共生体进化过程中的关键事件。