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 ...
of
Fungi within the
class 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 thalli from two-celled
ascospores. 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, 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 through which the fungus penetrates the exoskeleton of its host to draw nutrients from the
hemolymph. 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 (1858–1932), particularly in his five-volume, illustrated ''Monograph of the Laboulbeniaceae'' (Thaxter 1896, 1908, 1924, 1926, 1931).
Recent
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 ...
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
Further reading
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External links
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Bugguide.net. ''Harmonia axyridis'' with Laboulbeniales fungusArticle about Laboulbeniales on Diptera by Jan MácaLaboulbeniales homepage by Dr. Alex Weir
Ascomycota orders
{{Ascomycota-stub