Mycangia define the diverse ambrosia beetle–fungus symbioses
A chapter in the book Convergent Evolution of Agriculture in Humans and Insects (ISBN: 9780262543200; LINK at MIT Press).
The review covers all known types of ambrosia beetle mycangia, which beetles have them and what fungi have been found in them, representative illustrations, an overview of what we know and don't know about them, and a proposed theory of the "mycangium cycle". There is discussion about how mycangia may relate to beetle sociality, evolution, and fungal domestication, with reflections on human agriculture. Above all else I hope this helps mycangium research continue to build towards a better understanding of these amazing pockets.
The full text in .pdf format as printed in the book is available open access at MIT Press: LINK
The accepted manuscript, with color figures, is available at ResearchGate: LINK
CitationMayers CG, Harrington TC, Biedermann PHW, 2022. Mycangia define the diverse ambrosia beetle–fungus symbioses. In: Schultz TR, Peregrine PN, Gawne R, eds, The Convergent Evolution of Agriculture in Humans and Insects. MIT Press, Cambridge, MA.
Recent and Ongoing Horizontal Transfer of Mitochondrial Introns Between Two Fungal Tree Pathogens
This paper presents evidence for horizontal exchange of mitochondrial DNA in the two Rapid ʻŌhiʻa Death pathogens, Ceratocystis lukuohia and Ceratocystis huliohia, which co-infest diseased trees.
Mitogenomes of C. huliohia are identical, but those of C. lukuohia are nearly identical save for ten introns or homing endonuclease genes (HEGs) that occur randomly in isolates. All ten are in every C. huliohia isolate. The unusual thing about these ten regions is that they are 100% identical between the two pathogens, in stark contrast to every other intron and their mitogenomes in general. Phylogenies suggest these regions all originate in the Asian-Australian clade of Ceratocystis, which C. huliohia is a part of. The ten regions are in every C. huliohia isolate, but randomly present with no geographic pattern in C. lukuohia. It seems that C. lukuohia in places where both pathogens have co-existed longer have more variety and more total regions. Could this be ongoing horizontal transfer in co-infected trees?
The full text is available open access at Frontiers: LINK
CitationMayers CG, Harrington TC, Wai A, Hausner G, 2021. Recent and ongoing transfer of mitochondrial introns between two fungal tree pathogens. Frontiers in Microbiology 12:656609.
Four mycangium types and four genera of ambrosia fungi suggest a complex history of fungus farming in the ambrosia beetle tribe Xyloterini
This is a treatment of the farmed fungi of ambrosia beetle tribe Xyloterini. The three genera in the tribe unexpectedly had different mycangia and different ambrosia fungi, including the new ambrosia fungus genus Kaarikia from Xyloterinus and a newly described mycangium anatomy in Indocryphalus. This paper also serves as a treatment of the genus Phialophoropsis (Ceratocystidaceae), including several new species.
This paper further supports the theory that mycangia and the fungal cultivars they carry have intimate histories of co-evolution, which explains the diverse mycangium-cultivar patterns we see today. Xyloterini is not the origin of the first Ceratocystidaceae ambrosia fungi despite its old age; instead, Trypodendron seems to have picked up Phialophoropsis pretty recently, and the tribes' cultivar history is otherwise much more complicated.
The text is available, with subscription, at Taylor & Francis: LINK
An unformatted, accepted author's manuscript version is available on request.
CitationMayers CG, Harrington TC, McNew DL, Roeper RA, Biedermann PHW, Masuya H, Bateman CC, 2020. Four mycangium types and four genera of ambrosia fungi suggest a complex history of fungus farming in the ambrosia beetle tribe Xyloterini. Mycologia 112:1104–1137.
Patterns of coevolution between ambrosia beetle mycangia and the Ceratocystidaceae, with five new fungal genera and seven new species
This paper is a treatment of all ambrosia fungi in Ceratocystidaceae, including newly discovered genera that are the cultivars of tribe Scolytoplatypodini. The history and timing of domestication is discussed for the family, as well as more descriptions of sexual states (including incredibly large ascospores in Wolfgangiella) for these previously-assumed-asexual fungi. Placing these evolutionary leaps—new mycangia in beetles, and domestication in fungi—on a timeline told a story. Some mycangia co-originated with the fungi they carried, but the saucer-shaped Scolytoplatypodini mycangia were more complicated, and implies ancestral crop trading.
The full text is available open access at Ingenta Connect: LINK
CitationMayers CG, Harrington TC, Masuya H, Jordal BH, McNew DL, Shih H-H, Roets F, Kietzka GJ, 2020. Patterns of coevolution between ambrosia beetle mycangia and the Ceratocystidaceae, with five new fungal genera and seven new species. Persoonia 44:41–66.
New Meredithiella species from mycangia of Corthylus ambrosia beetles suggest genus-level coadaptation but not species-level coevolution
This paper treats the ambrosia fungi of the ambrosia beetle genus Corthylus, which are all found to be species of Meredithiella, including one new species. Variation in mycangium shape among Corthylus species is demonstrated. This paper rejects earlier hypotheses that Ceratocystidaceae fungal cultivars were species-specific to their beetle farmers; rather, the genera of Ceratocystidaceae appear to be attuned to certain types of large mycangia, but can be shared by closely related hosts with the same type of mycangia.
The full text is available at Taylor & Francis: LINK
CitationMayers CG, Bateman CC, Harrington TC, 2018. New Meredithiella species from mycangia of Corthylus ambrosia beetles suggest genus-level coadaptation but not species-level coevolution. Mycologia 110: 63–78.
First report of a sexual state in an ambrosia fungus: Ambrosiella cleistominuta sp. nov. associated with the ambrosia beetle Anisandrus maiche
This paper describes fertile cleistothecia in the newly described Ambrosiella cleistominuta, which was discovered being farmed by the recent invasive (to the USA) Anisandrus maiche. This is the first report of a sexual state in a confirmed mycangial ambrosia fungus, but it suggests that other ambrosia fungi may also produce cryptic sexual states in nature that have gone unnoticed.
The full text is available at Canadian Science Publishing: LINK
CitationMayers CG, Harrington TC, Ranger CM, 2017. First report of a sexual state in an ambrosia fungus: Ambrosiella cleistominuta sp. nov. associated with the ambrosia beetle Anisandrus maiche. Botany 95:503–512.
Three genera in the Ceratocystidaceae are the respective symbionts of three independent lineages of ambrosia beetles with large, complex mycangia
This paper describes a pattern of ambrosia fungi in Ambrosiella sensu lato with different types of large mycangia. Ambrosiella is then split into three genera that correspond with different types of large mycangia and which don't form a single monophyletic group of cultivars. Ambrosiella sensu stricto are found in beetles of the Xylosandrus complex (Xyloterini) which all have large mesonotal pouch mycangia. The resurrected (from Batra) Phialophoropsis are found in Trypodendron beetles which all have large prothoracic pleural mycangia. A new genus, Meredithiella, are found in Corthylus beetles which have large coiled tube mycangia. The three genera have distinctive differences in morphology.
The full text is available at Elsevier: LINK
CitationMayers CG, McNew DL, Harrington TC, Roeper RA, Fraedrich SW, Biedermann PHW, Castrillo LA, Reed SE, 2015. Three genera in the Ceratocystidaceae are the respective symbionts of three independent lineages of ambrosia beetles with large, complex mycangia. Fungal Biology 119: 1075–1092.