Department of Plant Pathology and Microbiology, Iowa State University, 2213 Pammel Drive, 1344 Advanced Teaching and Research Building , Ames, Iowa 50011.
Department of Biology, Alma College , Alma, Michigan 48801.
Mycologia. 2020 Nov-Dec;112(6):1104-1137. doi: 10.1080/00275514.2020.1755209. Epub 2020 Jun 18.
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 (, and ) and characterized their ambrosia fungi in pure culture and by DNA sequencing. The prothoracic mycangia of seven species all yielded (Microascales) ambrosia fungi, including three new species, although these relationships were not all species specific. mycangia are characterized for the first time in the Asian . They comprise triangular prothoracic cavities substantially smaller than those of and unexpectedly carry an undescribed species of (Microascales), which are otherwise ambrosia fungi of Asian (Scolytoplatypodini). has two different mycangia, each with a different ambrosia fungus: cf. RNC5 (Ophiostomatales) in oral mycangia of both sexes and (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, and harbor a surprising diversity of facultative symbionts in their galleries, including . 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.
南洋杉小蠹甲虫养殖真菌品种（粉状真菌），并在称为菌囊的贮藏器官中携带真菌共生体的繁殖体，这些菌囊存在于各种身体部位，大小和复杂性差异很大。粉状真菌的进化与携带它们的菌囊的进化和发展密切相关。研究较少的南洋杉小蠹甲虫部落包括具有未被描述的粉状真菌和菌囊的谱系，这为测试单一南洋杉小蠹甲虫谱系中不同菌囊类型的发展是否与它们真菌共生体的同时多样性相对应提供了机会。我们收集了所有三个南洋杉小蠹甲虫属（、和）的代表，并通过纯培养和 DNA 测序对其粉状真菌进行了表征。七个 物种的前胸菌囊均产生 （微粉科）粉状真菌，包括三个新物种，尽管这些关系并非全部是种特异性的。 菌囊首次在亚洲 中得到描述。它们由三角形的前胸腔组成，明显小于 和 ，并且出人意料地携带一种未被描述的 （微粉科）物种，而这些物种通常是亚洲 （长角象科）的粉状真菌。 有两种不同的菌囊，每种菌囊都有一种不同的粉状真菌：两性的口腔菌囊中为 cf. RNC5（小囊科），而雌性的浅前胸菌囊中为 （子囊菌门，与 Distoseptisporaceae 科亲缘关系密切的未确定属），这是一种与其他已知粉状真菌无关的新属和新种。除了高度适应的菌囊共生体外，和 还在其坑道中拥有多种兼性共生体，包括 。粉状真菌和菌囊的多样性表明，在南洋杉小蠹甲虫部落的历史中，存在多次祖先培养物的捕获或转换，每次转换都与菌囊解剖结构的独特适应相关。这进一步支持了这样一种理论，即新型菌囊类型的发展是粉状真菌和它们共生真菌共同进化的关键事件。
