Misplaced Pages

#826173

23-673: The Mygalomorphae , or mygalomorphs , are an infraorder of spiders , and comprise one of three major groups of living spiders with over 3,000 species, found on all continents except Antarctica. Many members are known as trapdoor spiders due to their creation of trapdoors over their burrows. Other prominent groups include Australian funnel web spiders and tarantulas , with the latter accounting for around one third of all mygalomorphs. This group of spiders comprises mostly heavy-bodied, stout-legged spiders including tarantulas , Australian funnel-web spiders , mouse spiders , and various families of spiders commonly called trapdoor spiders . Like

46-461: A cohors (plural cohortes ). Some of the plant families still retain the names of Linnaean "natural orders" or even the names of pre-Linnaean natural groups recognized by Linnaeus as orders in his natural classification (e.g. Palmae or Labiatae ). Such names are known as descriptive family names. In the field of zoology , the Linnaean orders were used more consistently. That is,

69-509: A capital letter. For some groups of organisms, their orders may follow consistent naming schemes . Orders of plants , fungi , and algae use the suffix -ales (e.g. Dictyotales ). Orders of birds and fishes use the Latin suffix -iformes meaning 'having the form of' (e.g. Passeriformes ), but orders of mammals and invertebrates are not so consistent (e.g. Artiodactyla , Actiniaria , Primates ). For some clades covered by

92-534: A cladogram showing family relationships was published in 2005, with two significant studies in 2018. The division of Mygalomorphae into two superfamilies, Atypoidea and Avicularioidea , has been established in many studies. The Atypoidea retain some vestiges of abdominal segmentation in the form of dorsal tergites ; the Avicularioidea lack these. Molecular phylogenetic studies undertaken between 2012 and 2017 have found somewhat different relationships within

115-570: A distinct rank of biological classification having its own distinctive name (and not just called a higher genus ( genus summum )) was first introduced by the German botanist Augustus Quirinus Rivinus in his classification of plants that appeared in a series of treatises in the 1690s. Carl Linnaeus was the first to apply it consistently to the division of all three kingdoms of nature (then minerals , plants , and animals ) in his Systema Naturae (1735, 1st. Ed.). For plants, Linnaeus' orders in

138-585: A giant mygalomorph from the Upper Carboniferous (about 350 million years ago), but was later found to be a eurypterid . The oldest known mygalomorph is Rosamygale grauvogeli , an avicularoid from the Triassic of northeastern France. No mygalomorphs from the Jurassic have yet been found. The number of families and their relationships have both been undergoing substantial changes since

161-448: A metre in diameter. Unlike Araneomorphae , which die after about a year, Mygalomorphae can live for up to 25 years, and some do not reach maturity until they are about six years old. Some flies in the family Acroceridae that are endoparasites of mygalomorphs may remain dormant in their book lungs for as long as 10 years before beginning their development and consuming the spider. One female trapdoor spider, first recorded in

184-715: A new subfamily, Australothelinae, was generated and placed in the family Euagridae. The preferred cladogram from Optova et al. (2020) is: Hexurellidae Mecicobothriidae Atypidae Megahexuridae Antrodiaetidae Ischnothelidae Microhexuridae Hexathelidae Euagridae Porrhothelidae Macrothelidae Paratropididae Stasimopidae Atracidae Actinopodidae Halonoproctidae Migidae Idiopidae Ctenizidae Euctenizidae Bemmeridae Barychelidae Theraphosidae Nemesiidae Pycnothelidae Dipluridae Cyrtaucheniidae Anamidae Entypesidae Microstigmatidae In 1802, C. A. Walckenaer separated mygalomorph spiders into

207-758: A separate genus , Mygale , leaving all other spiders in Aranea In 1985, Robert Raven published a monograph of the Mygalomorphae in which he proposed an internal classification for the Mygalomorphae, based on morphological features. Opatova et al . (2020) commented "In short, much of today's classification scheme dates back to Raven (1985)". Raven used various compound ranks, such as "gigapicoorder" and "hyperpicoorder". Ignoring these unusual rank names, his classification can be shown diagrammatically: Mecicobothriidae Microstigmatidae Hexathelidae Infraorder What does and does not belong to each order

230-526: A survey in 1974 in Western Australia, is known to have lived for 43 years. 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 (as they do in the araneomorphs ). Megarachne servinei was thought to be

253-419: Is determined by a taxonomist , as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with

SECTION 10

#1732780659827

276-528: The International Code of Zoological Nomenclature , several additional classifications are sometimes used, although not all of these are officially recognized. In their 1997 classification of mammals , McKenna and Bell used two extra levels between superorder and order: grandorder and mirorder . Michael Novacek (1986) inserted them at the same position. Michael Benton (2005) inserted them between superorder and magnorder instead. This position

299-815: The Systema Naturae and the Species Plantarum were strictly artificial, introduced to subdivide the artificial classes into more comprehensible smaller groups. When the word ordo was first consistently used for natural units of plants, in 19th-century works such as the Prodromus Systematis Naturalis Regni Vegetabilis of Augustin Pyramus de Candolle and the Genera Plantarum of Bentham & Hooker, it indicated taxa that are now given

322-977: The araneomorphs , evolved new "modern" features, including a cribellum and cross-acting fangs. Mesotheles retain the external abdominal segmentation of ancestral arachnids and have at least vestiges of four pairs of spinnerets, whereas mygalomorphs lack abdominal segmentation (like other opistotheles) and have a reduced number of spinnerets, often only two pairs. Like spiders in general, most species of Mygalomorphae have eight eyes, one pair of principal and three pairs of secondary eyes. Their chelicerae and fangs are large and powerful and have ample venom glands that lie entirely within their chelicerae . These weapons, combined with their size and strength, make Mygalomorph spiders powerful predators. Many of these spiders are well adapted to killing other large arthropods and will also sometimes kill small mammals , birds , and reptiles . Despite their fearsome appearance and reputation, most mygalomorph spiders are not harmful to humans, with

345-472: The " primitive " suborder of spiders Mesothelae , they have two pairs of book lungs , and downward-pointing chelicerae . Because of this, the two groups were once believed to be closely related. Later it was realised that the common ancestors of all spiders had these features (a state known as symplesiomorphy ). Following the branching into the suborders of Mesothelae and Opisthothelae , the mygalomorphs retained them, while their fellow Opisthothelae members,

368-758: The Avicularioidea. Some families appear not to be monophyletic and further changes are possible in the future. Rosamygale belongs to Avicularioidea, based on the absence of an abdominal scutum and well-separated posterior lateral spinnerets. Mygalomorphae tend to be highly morphologically conserved, which makes it difficult to find reliable morphological features to use for taxonomy. It has been hypothesized that because Mygalomorphae all tend to be fossorial and live in tubular webs, they are subjected to similar selective pressures, so most species should evolve in similar ways. Additionally, this may also mean that homoplasies are more likely to occur, further complicating taxonomy based on morphology. The relationships of taxa in

391-426: The Mygalomorphae were restructured based on a comprehensive phylogenetic study by Opatova et al . (2020) The generic composition of the families Ctenizidae, Cyrtaucheniidae, Dipluridae, and Nemesiidae were relimited. Five subfamilies were raised to the rank of family: Anamidae, Euagridae, Ischnothelidae, Pycnothelidae, and Bemmeridae. Three new families were created: Entypesidae, Microhexuridae, and Stasimopidae. Lastly,

414-505: The exception of the Australian funnel-web spiders , especially those of the genus Atrax . While the world's biggest spiders are mygalomorphs – Theraphosa blondi has a body length of 10 cm (3.9 in) and a leg span of 28 cm (11 in) – some species are less than one millimeter (0.039 in) long. Mygalomorphs are capable of spinning at least slightly adhesive silk, and some build elaborate capture webs that approach

437-708: The orders in the zoology part of the Systema Naturae refer to natural groups. Some of his ordinal names are still in use, e.g. Lepidoptera (moths and butterflies) and Diptera (flies, mosquitoes, midges, and gnats). In virology , the International Committee on Taxonomy of Viruses 's virus classification includes fifteen taxomomic ranks to be applied for viruses , viroids and satellite nucleic acids : realm , subrealm , kingdom , subkingdom, phylum , subphylum , class, subclass, order, suborder, family, subfamily , genus, subgenus , and species. There are currently fourteen viral orders, each ending in

460-564: The precursor of the currently used International Code of Nomenclature for algae, fungi, and plants . In the first international Rules of botanical nomenclature from the International Botanical Congress of 1905, the word family ( familia ) was assigned to the rank indicated by the French famille , while order ( ordo ) was reserved for a higher rank, for what in the 19th century had often been named

483-502: The rank of family (see ordo naturalis , ' natural order '). In French botanical publications, from Michel Adanson 's Familles naturelles des plantes (1763) and until the end of the 19th century, the word famille (plural: familles ) was used as a French equivalent for this Latin ordo . This equivalence was explicitly stated in the Alphonse Pyramus de Candolle 's Lois de la nomenclature botanique (1868),

SECTION 20

#1732780659827

506-553: The suffix -virales . Atypoidea See text. Atypoidea is a clade of mygalomorph spiders, one of the two main groups into which the mygalomorphs are divided (the other being Avicularioidea ). It has been treated at the rank of superfamily. It contains five families of spiders: Spiders from atypoid families live in burrows and use silk to build many different types of burrow entrance constructs, including purse webs, trapdoors, funnel-and-sheet webs, turrets and silken collars. The following cladogram illustrates

529-418: Was adopted by Systema Naturae 2000 and others. In botany , the ranks of subclass and suborder are secondary ranks pre-defined as respectively above and below the rank of order. Any number of further ranks can be used as long as they are clearly defined. The superorder rank is commonly used, with the ending -anae that was initiated by Armen Takhtajan 's publications from 1966 onwards. The order as

#826173