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Arthrobotrys

Arthrobotrys is a genus of mitosporic fungi in the family Orbiliaceae. They are predatory fungi that capture and feed on nematode worms.

Predetory Mechanisms

Arthrobotrys are known to form rings with their hyphae to constrict and entrap nematodes, which then grow into the worm and digest it.

In 1888, Zopf described the unique phenomenon in which Arthrobotrys oligospora produces adhesion networks to capture nematodes. He described how Arthrobotrys can produce a variety of trap morphologies, ranging from simple adhesive hyphae to complex adhesive trapping structures. Some species are even known to immobilise nematodes remotely, which indicates an ability to secrete specific nematotoxic metabolites.

A majority of Arthrobotrys capture and consume copepods, mites, collembola, dipterans, but primarily nematodes.. They have been tested for potential use in pest biocontrol.

Taxonomy

Arthrobotrys is the largest genus among Orbiliaceae. At present, 166 species are listed in the Species Fungorum.

The genus Arthrobotrys was first described and named by Corda in 1839, with A. superba as the type species. He based the description on their conidial and trapping mechanisms. Previously, all taxa that produced adhesive networks were referred to as Arthrobotrys.

These taxa are characterised by regularly 1-septate conidia growing on the nodes or short denticles of conidiophores. At the time of its establishment, this genus was known for saprobic taxa.

The Arthrobotrys clade as treated by Baral et al. (2018). includes five unpublished infrageneric taxa, which are basically equivalent to the five previously described genera Arthrobotrys, Dactylella Grove, Dactylellina Morelet, Drechslerella Subram. and Gamsylella.. Of these genera, four are predacious and monophyletic, whereas Dactylella, which comprises all non-predacious members of the group, is paraphyletic according to Baral & al. (2018) . More than 100 species have been published in the genus Arthrobotrys. However, Scholler & al. (1999) recognised only 46 species in the genus when newly circumscribed to include those species with three-dimensional adhesive networks. Teleomorphs of the Arthrobotrys clade are mostly characterised by narrow, subulate and curved, falcate ascospores with a small, apical spore body .

Anamorph-Teleomorph Relation

Fungi of the Arthrobotrys complex are anamorphs of species of discomycetes in the family Orbiliaceae. This means that Arthrobotrys is the predatory, asexual and anamorphic stage while Orbilia produces the spores and is hence the sexual and teleomorph stage. Because life cycles in some fungi are polymorphic and include both meiosporic and mitosporic structures (teleomorphs and anamorphs), occurring separately in space and time, the same species may have been studied and named independently , hence being a good example of the problem of dual names.

Dual Names

When recognising the genus Orbilia in a wide sense, then under the one-fungus-one-name rule, the name Orbilia takes precedence over Arthrobotrys. Members of Orbilia with predacious capabilities together with some non-predacious taxa form a monophyletic group, here referred to as the Arthrobotrys clade.

Species connection

Studies have linked specific Orbilia species to Arthrobotrys types, such as Orbilia blumenaviensis producing Arthrobotrys vermicola.

Habitat

Arthrobotrys are widely distributed in soil, decomposing organic matter, and fresh water. They are mainly nematophagous but also mycoparasitic. Fungi with this lifestyle often occur in microhabitats with low concentrations of available nitrogen.</ref>

Species

References