The Mygalomorphae, or mygalomorphs, are an infraorder of spiders. The name is derived from the Greek mygalē, meaning "shrew", plus morphē meaning form or shape. An older name for the group is Orthognatha, derived from the orientation of the fangs which point straight down and do not cross each other. In 1802, C. A. Walckenaer separated mygalomorph spiders into a separate genus, Mygale, leaving all other spiders in Aranea.
Ctenizidae is a small family of medium-sized mygalomorph spiders that construct burrows with a cork-like trapdoor made of soil, vegetation and silk. They may be called trapdoor spiders, as are similar species, such as those of the families Liphistiidae, Barychelidae, Cyrtaucheniidae and some species in Idiopidae and Nemesiidae. In 2018, the family Halonoproctidae was split off from Ctenizidae, leaving only three genera.
The wafer trapdoor spiders, family Cyrtaucheniidae, are a widespread family of spiders that lack the thorn-like spines on tarsi and metatarsi I and II found in true trapdoor spiders (Ctenizidae).
Nemesiidae, also known as funnel-web trapdoor spiders, is a family of mygalomorph spiders first described by Eugène Simon in 1889, and raised to family status in 1985. Before becoming its own family, it was considered part of "Dipluridae".
Barychelidae, also known as brushed trapdoor spiders, is a spider family with about 300 species in 42 genera. Most spiders in this family build trapdoor burrows. For example, the 20 millimetres (0.79 in) long Sipalolasma builds its burrow in rotted wood, with a hinged trapdoor at each end. The 10 millimetres (0.39 in) long Idioctis builds its burrow approximately 5 centimetres (2.0 in) deep, just below the high tide level, sealing the opening with a thin trapdoor.
Antrodiaetidae, also known as folding trapdoor spiders, is a small spider family related to atypical tarantulas. They are found almost exclusively in the western and midwestern United States, from California to Washington and east to the Appalachian mountains. Exceptions include Antrodiaetus roretzi and Antrodiaetus yesoensis, which are endemic to Japan and are considered relict species. It is likely that two separate vicariance events led to the evolution of these two species.
Migidae, also known as tree trapdoor spiders, is a family of spiders with about 100 species in eleven genera. They are small to large spiders with little to no hair and build burrows with a trapdoor. Some species live in tree fern stems. They have a Gondwanan distribution, found almost exclusively on the Southern Hemisphere, occurring in South America, Africa, Madagascar, Australia, New Zealand and New Caledonia.
Homalonychus is a genus of araneomorph spiders, and is the only genus in the family Homalonychidae. It was first described by George Marx in 1891. As of May 2019 it contains only three species: H. raghavai, H. selenopoides, and H. theologus. Two are found in the southern United States and Mexico: H. theologus is mostly found west of the Colorado River, while H. selenopoides is mostly found to the east, with some populations in Death Valley and near Mercury, Nevada.
Atypoidea is a clade of mygalomorph spiders, one of the two main groups into which the mygalomorphs are divided. It has been treated at the rank of superfamily. It contains five families of spiders:
Myrmekiaphila is a genus of North American mygalomorph trapdoor spiders in the family Euctenizidae, and was first described by G. F. Atkinson in 1886. All described species are endemic to the southeastern United States.
Aptostichus is a genus of North American mygalomorph spiders in the family Euctenizidae, and was first described by Eugène Simon in 1891. They are found predominantly in southern California, United States.
Antrodiaetus is a genus of American and Japanese folding trapdoor spiders first described by Anton Ausserer in 1871. The name is a combination of the Greek "antrodiaitos" (αντροδιαιτος), meaning "living in caves", "antron" (αντρον), meaning "cave", and "diaita (διαιτα), meaning "way of life, dwelling".
The Euctenizidae are a family of mygalomorph spiders. They are now considered to be more closely related to Idiopidae.
Eucteniza is a genus of trapdoor spiders in the family Euctenizidae containing at least 14 species occurring in Mexico and the southern United States. Species are distinguished by a softened rear portion of the carapace, and males possess large spines on the first two pairs of walking legs that are used to hold females during mating. Like other trapdoor spiders they create burrows with a hinged lid, from which they await passing insects and other arthropods to prey upon. Many species are known from only one or two localities, or from only male specimens. More species are expected to be discovered. Eucteniza is closely related to spiders of the genera Entychides and Neoapachella.
Antrodiaetus pugnax is a species of folding-door spider in the family Antrodiaetidae. It is found in the United States.
Bipectina is a clade of avicularioid mygalomorph spiders first proposed by Pablo A. Goloboff in 1993, based on a morphological cladistic analysis. The clade was marked by a number of morphological features, and in particular by the presence of two rows of teeth on the superior tarsal claws of the legs of both sexes, meaning that the claws were bipectinate. The clade was supported by some subsequent analyses, although not all. A major phylogenetic study in 2020 upheld the monophyly of the clade, which contained 19 of the 25 accepted families of the Avicularioidea.
Domiothelina is a clade of avicularioid mygalomorph spiders first proposed by Robert J. Raven in 1985, based on a morphological cladistic analysis. Raven characterized the clade by a number of shared features, including the domed apical segment of the posterior lateral spinnerets. The clade has been supported to some degree by subsequent molecular analyses, although with a somewhat different composition.
Crassitarsae is a clade of avicularioid mygalomorph spiders first proposed by Robert J. Raven in 1985, based on a morphological cladistic analysis. Raven characterized the clade by a number of shared features, including the presence of some scopulae on the tarsi. The clade has been supported to some degree by subsequent molecular analyses, although with a somewhat different composition.
Nemesioidina is a clade of avicularioid mygalomorph spiders proposed in 2020, based on a molecular phylogenetic analysis.
