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The term mycangium (pl., mycangia) is used in biology for special structures on the body of an animal that are adapted for the transport of symbiotic fungi (usually in spore form). This is seen in many xylophagous insects (e.g. horntails and bark beetles), which apparently derive much of their nutrition from the digestion of various fungi that are growing amidst the wood fibers. In some cases, as in ambrosia beetles, the fungi are the sole food, and the excavations in the wood are simply to make a suitable microenvironment for the fungus to grow. In other cases (e.g., the southern pine beetle, Dendroctonus frontalis), wood tissue are the main food, and fungi weaken the defense response from host plant.

There are mites which have their own type of mycangium (for historical reasons, mite taxonomists use the term sporotheca), and the mites ride on the beetles.

Origin
These structures were first described by Professor Helene Francke-Grosmann. Then Batra coined the word mycangia: modern Latin, from Greek myco 'fungus' + angeion 'vessel'.

Function
These most function of mycangia are preserving and releasing symbiont. In usual the symbiotic inoculum in mycangia will provide great help to their vectors. They could help vector adapt to the new environment or become nutrient of the vectors themselves and their descendant. Therefore mycangia play a important role in protecting the inoculum from degrading and contaminating. Hence, the structures of mycangia always look like a pouch or a container with caps or small opening, so that reduce the possibility of contaminate from outside. How do mycangia release their inoculum is still unknown now.

Mycangium in bark and ambrosia beetles
Mycangia of bark and ambrosia beetles (Curculionidae: Scolytinae and Platypodinae) are often complex cuticular invaginations for transport of symbiotic fungi. Several types exist. Phloem-feeding bark beetles (Coleoptera: Curculionidae: Scolytinae) have usually numerous small pits on the surface of their body, while ambrosia beetles (many Scolytinae and all Platypodinae), which are completely dependent on their fungal symbiont, have deep and complicated pouches. These mycangia are often equipped with glands secreting substances to support fungal spores and perhaps to nourish mycelium during transport. In many cases, the entrance to a mycangium is surrounded by tufts of setae, aiding in scraping mycelium and spores from walls of the tunnels and directing the spores into the mycangium. The mycangia in ambrosia beetle are highly diversity. Different genera or tribe of beetle always utilize different kinds of mycangia. Some are oral mycangia, such as genus Ambrosiodmus and Euwallacea. Some are pronotal mycangia, such Xylosandrus and Cnestus.

Mycangium in woodwasp (horntail)
Mycangia of woodwasp (Hymenoptera: Siricidae) was first described by Buchner. Different from high diversity of mycangia in bark and ambrosia beetles, woodwasps have a pair of mycangia on the top of their ovipositor. Then when female deposited their egg inside the host plant, they injected the symbiotic fungi from mycangia and phytotoxic mucus from another reservoir-like structure.

Mycangium in lizard beetle
One species of lizard beetle Doubledaya bucculenta (Coleoptera: Erotylidae: Languriinae) has mycangia on the tergum of the eighth abdominal segment. This ovipositor-associated mycangia only present in adult female. Before Doubledaya bucculentnta deposited their eggs and injected the symbiotic microorganisms on a recently dead bamboo, they will excavate a small hole through the bamboo culm.

Mycangium in ship-timber beetle
Ship-timber beetle (Coleoptera: Lymexylonidae) is another family of wood-boring beetles live with symbiotic fungi. Buchner first discovered their mycangia are located in ventral side of the long ovipositor☃☃. This mycangia are form of a pair of integumental pouches at either side near the tip of oviduct. When female laid the eggs, new eggs are coated with the fungal spores.

Mycangium in leaf-rolling weevil
Females of the leaf-rolling weevil in the genus Euops (Coleoptera: Attelabinae) store symbiotic fungi in the mycangia which is between the first ventral segment of abodomen and thorax. Different from ovipositor-associate mycangia in woodwasp, lizard beetle, and ship-timber beetle, mycangia of leaf-rolling weevil is a pair of spore incubators at the anterior end of the abdomen. This mycangia formed by the coxa and the metendosternite, at the posterior end of the thorax.

Mycangium and symbiotic inoculum
Most of inoculum in mycangia are fungi. The symbiotic inoculum of most bark and ambrosia beetle are fungi belong to Ophistomatales (Ascomycota: Sordariomycetidae) and Microascales (Ascomycota:Hypocreomycetidae)☃☃. Symbiotic fungi in mycangiaia of woodwasp are Amylostereaceae (Basidiomycota: Russulales)☃☃. Symbiotic fungi in mycangiaia of lizard beetle are yeast (Ascomycota: Saccharomycetales)☃☃. Symbiotic fungi in mycangiaia of ship-timber beetle are Endomyces (Ascomycota: Dipodascaceae). Symbiotic fungi in mycangiaia of leaf-rolling weevil are Penicillium fungi (Ascomycota: Trichocomaceae).