The Laboulbeniales is an

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

within the

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

Laboulbeniomycetes The Laboulbeniomycetes are a unique group of fungi that are obligatorily associated with arthropods, either as external parasites ( Herpomycetales and Laboulbeniales) or for dispersal ( Pyxidiophorales). Herpomycetales and Laboulbeniales fun ...

. They are also known by the colloquial name beetle hangers or labouls. The order includes around 2,325 species of

obligate {{wiktionary, obligate As an adjective, obligate means "by necessity" (antonym ''facultative'') and is used mainly in biology in phrases such as: * Obligate aerobe, an organism that cannot survive without oxygen * Obligate anaerobe, an organism that ...

insect ectoparasites that produce

cellular Cellular may refer to: *Cellular automaton, a model in discrete mathematics * Cell biology, the evaluation of cells work and more * ''Cellular'' (film), a 2004 movie *Cellular frequencies, assigned to networks operating in cellular RF bands *Cell ...

thalli from two-celled

ascospore An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...

s. Of the described Laboulbeniales, Weir and Hammond 1997 find 80% to be from

Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

and the next largest group to be the 10% from

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

. Recently, the genus ''

Herpomyces ''Herpomyces'' is a fungal genus in the order Herpomycetales (Laboulbeniomycetes), with species that are exclusively ectoparasites of members of the Blattodea order (cockroaches). As of 2020, 27 species of ''Herpomyces'' are formally described. ...

'', traditionally considered a basal member of Laboulbeniales, was transferred to the order

Herpomycetales The Herpomycetales is an order of fungi within the class Laboulbeniomycetes. The order includes a single dioecious genus, '' Herpomyces'', with 27 accepted species of obligate ectoparasites that are associated exclusively with cockroaches. Li ...

based on

molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

data. Laboulbeniales typically do not kill their hosts, although they may impair host fitness if the parasite density is high. Laboulbeniales form individual

thalli Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms were ...

, and lack vegetative

hyphae A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

. A thallus is attached to its host by a simple dark-colored foot cell, or a rhizoidal

haustorium In botany and mycology, a haustorium (plural haustoria) is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates t ...

through which the fungus penetrates the exoskeleton of its host to draw nutrients from the

hemolymph Hemolymph, or haemolymph, is a fluid, analogous to the blood in vertebrates, that circulates in the interior of the arthropod (invertebrate) body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which ...

. The external part of the thallus may form male structures (antheridia) or female structures (trichogynes and perithecia), or both. New infections are initiated when spores from the perithecia attach to a compatible insect host. Spore transmission can sometimes occur during insect copulation, which may account for the different site specificity sometimes observed in male and female hosts. These fungi do not grow apart from their hosts. Foundational work on the Laboulbeniales was completed by the American mycologist

Roland Thaxter Roland Thaxter (August 28, 1858 – April 22, 1932) was an American mycologist, plant pathologist, botanist, and entomologist, renowned for his contribution to the insect parasitic fungi—Laboulbeniales. His college education was completed at Har ...

(1858–1932), particularly in his five-volume, illustrated ''Monograph of the Laboulbeniaceae'' (Thaxter 1896, 1908, 1924, 1926, 1931). Recent

work has shown that some taxa are complexes of multiple species segregated by host, for example ''Hesperomyces virescens''. The classification of the order Laboulbeniales follows Isabelle Tavares (1985) but several taxa in that system are polyphyletic.

References

External links

*
Bugguide.net. ''Harmonia axyridis'' with Laboulbeniales fungusArticle about Laboulbeniales on Diptera by Jan MácaLaboulbeniales homepage by Dr. Alex Weir
Ascomycota orders {{Ascomycota-stub

References

Further reading

External links