The Orbiliaceae are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

saprobic Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi (f ...

sac fungi Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The defi ...

in the

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 ...

Orbiliales. The family, first described by

John Axel Nannfeldt John-Axel Nannfeldt (baptized ''Johan Axel Frithiof Nannfeldt''), born 18 January 1904 in Trelleborg and deceased 4 November 1985 in Uppsala, was a Swedish botanist and mycologist. Nannfeldt studied natural history at the University of Uppsal ...

in 1932, contains 288

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

in 12

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

. Members of this family have a widespread distribution, but are more prevalent in

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

regions. Some species in the Orbiliaceae are

carnivorous fungi Carnivorous fungi or predaceous fungi are fungi that derive some or most of their nutrients from trapping and eating microscopic or other minute animals. More than 200 species have been described, belonging to the phyla Ascomycota, Mucoromycotina, ...

, and have evolved a number of specialized mechanisms to trap

nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...

Description

Orbiliaceae do not have stromata, dense structural tissue that produces

fruit bodies The sporocarp (also known as fruiting body, fruit body or fruitbody) of fungi is a multicellular structure on which spore-producing structures, such as basidia or asci, are borne. The fruitbody is part of the sexual phase of a fungal life cyc ...

. They have small disc-shaped

apothecia An ascocarp, or ascoma (), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascocarps are mo ...

, that are typically convex, brightly colored or

translucent In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions a ...

. Their

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 are small (typically less than 10 x 1 μm),

hyaline A hyaline substance is one with a glassy appearance. The word is derived from el, ὑάλινος, translit=hyálinos, lit=transparent, and el, ὕαλος, translit=hýalos, lit=crystal, glass, label=none. Histopathology Hyaline cartilage is ...

, and have an oval or ellipsoidal shape. Species are usually found in wood on both wet and dry habitats.

Anamorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

species are hyphomycetous.

Nematophagy

This family is well known for its many nematophagous species. Shortly after coming into contact with its prey, fungal

mycelia Mycelium (plural mycelia) is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates in ...

penetrate the nematode and spontaneously differentiate into functional structures, known as traps, which will ultimately digest the nematode's internal contents. There are 5 types of trap mechanisms recognized in this family: *Adhesive network: the most common trap, formed by

hypha 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 ...

l outgrowths that recurve into themselves to form nematode-trapping loops. *Adhesive knob: a roughly spherical cell, attached to the hyphae either directly or on an erect stalk. Adhesive knobs are typically closely spaced along a section of hyphae. *Nonconstricting rings: always found with the adhesive network traps, and formed from thickening hyphae that curve and fuse to the supporting stalk. *Adhesive column: a layer of cells on a hyphae with an adhesive surface. *Constricting rings: these are rings of hyphae that swell rapidly inwards upon contact with the nematode, quickly (in 1–2 seconds) "

lasso A lasso ( or ), also called lariat, riata, or reata (all from Castilian, la reata 're-tied rope'), is a loop of rope designed as a restraint to be thrown around a target and tightened when pulled. It is a well-known tool of the Spanish an ...

ing" the victim.

Genera

According to the most recent classification of Ascomycota, the Orbiliaceae contain only two (

teleomorph In mycology, the terms teleomorph, anamorph, and holomorph apply to portions of the life cycles of fungi in the phyla Ascomycota and Basidiomycota: *Teleomorph: the sexual reproductive stage (morph), typically a fruiting body. *Anamorph: an ase ...

) genera, the '' Hyalorbilia'' and the ''

Orbilia ''Orbilia'' is a genus of fungi in the family (biology), family Orbiliaceae. Anamorphs of this genus include the ''Arthrobotrys'', ''Dactylella'', ''Dicranidion'', ''Dwayaangam'', ''Helicoön'', ''Monacrosporium'', and ''Trinacrium''. The genus w ...

''. ''Hyalorbilia'' is distinguished from ''Orbilia'' by having

asci ASCI or Asci may refer to: * Advertising Standards Council of India * Asci, the plural of ascus, in fungal anatomy * Accelerated Strategic Computing Initiative * American Society for Clinical Investigation * Argus Sour Crude Index * Association of ...

without a stalk that arise from

crozier A crosier or crozier (also known as a paterissa, pastoral staff, or bishop's staff) is a stylized staff that is a symbol of the governing office of a bishop or abbot and is carried by high-ranking prelates of Roman Catholic, Eastern Catholi ...

s, a hemispherical to broadly conical, thin-walled apex, asci and

paraphyses Paraphyses are erect sterile filament-like support structures occurring among the reproductive apparatuses of fungi, ferns, bryophytes and some thallophytes. The singular form of the word is paraphysis. In certain fungi, they are part of the fe ...

in a gelatinous matrix, and an ectal excipulum (the outer surface of a cup-like apothecium) of horizontal textura prismatica.

genera of the Orbiliaceae include '' Anguillospora'', ''

Arthrobotrys ''Arthrobotrys'' is a genus of mitosporic fungi in the family Orbiliaceae. There are 71 species. They are predatory fungi that capture and feed on nematode worms. Rings that form on the hyphae constrict and entrap the worms, then hyphae grow int ...

'', '' Dactylella'', '' Dactylellina'', '' Dicranidion'', '' Drechslerella'', '' Helicoön'', '' Monacrosporium'', and '' Trinacrium''. It has been suggested that the anamorph specialization illustrates

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...

occurring among

l fungi in aquatic and low-

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

habitats. This hypothesis has been borne out by recent phylogenetic and morphological studies. In 2007, a new species was described from southwestern China with morphological features intermediate between ''Orbilia'' and ''Hyalorbilia''. This species, named ''Pseudorbilia bipolaris'' Y. Zhang, Z.F. Yu, H.O. Baral & K.Q. Zhang, was placed into its own genus in the Orbiliaceae to accommodate its distinctive features.

References

External links

Images of various ''Orbilia'' and ''Hyalorbilia'' species

Videos of ''Arthrobotrys oligospora'' trapping nematodes
{{Taxonbar, from=Q1517480, from2=Q10611127 Pezizomycotina Ascomycota families Taxa named by John Axel Nannfeldt Taxa described in 1932