Actinotrichida
Acariformes is one of two superorders of mites, representing the more diverse lineage with over 32,000 described species in 351 families and an estimated total of 440,000–929,000 species. Recent phylogenomic analyses indicate Acariformes is the most deeply rooted chelicerate lineage, rendering the traditional grouping of all mites into a single taxon scientifically problematic. The superorder comprises two main clades: Sarcoptiformes (including Oribatida and Astigmatina) and Trombidiformes, with the enigmatic Endeostigmata representing primitive forms of uncertain placement.
dwarf spiders
Allomengea is a genus of dwarf spiders in the family Linyphiidae, first described by Embrik Strand in 1912. The genus contains six species with a primarily Holarctic distribution, ranging from North America across Eurasia to East Asia. Species occur in diverse habitats including boreal and temperate regions, with some showing broad transcontinental ranges while others are restricted to specific regions such as the Korean Peninsula or China.
Hackledmesh Weavers, Night Spiders, Laceweavers
Amaurobiidae is a family of three-clawed spiders found worldwide, containing approximately 286 species in 51 genera. Members are characterized by possessing either a cribellum (a silk-spinning plate) or being ecribellate, and are often difficult to distinguish from related families such as Agelenidae, Desidae, and Amphinectidae. The family's taxonomic boundaries and internal relationships have been historically contentious, with genera frequently reassigned between families based on morphological and molecular studies. Australian representatives are small to medium-sized entelegyne spiders with minimal sheet webs, while North American species include relatively large, powerful hunters.
Anahita is a genus of wandering spiders in the family Ctenidae, established by Karsch in 1879. The genus name derives from an Iranian goddess associated with waters and fertility. These spiders are part of the diverse tropical and subtropical spider fauna, with species distributed across parts of Asia and Africa. As ctenids, they possess characteristic eye arrangements and are active hunters rather than web-builders.
spiders
Araneae is an order of air-breathing arachnids comprising over 51,000 described species across 136 families, ranking seventh in total species diversity among all organismal orders. Members are characterized by two body regions (cephalothorax and unsegmented abdomen), eight legs, cheliceral fangs with venom glands, and abdominal spinnerets that produce silk. The order is divided into two suborders: Mesothelae (87 species, retaining abdominal segmentation) and Opisthothelae (over 39,000 species, without abdominal segmentation). Spiders occupy virtually all terrestrial habitats worldwide except Antarctica, functioning exclusively as predators of insects and other small arthropods.
fat-tailed scorpions, bark scorpions, arrowbreasted scorpions
Buthidae is the largest family of scorpions, containing approximately 100 genera and 1300 species as of 2025. Members are typically mid-sized to small, with weak, slender pedipalps and characteristically thickened tails. The family has a cosmopolitan distribution throughout tropical and subtropical environments worldwide. Buthidae includes nearly all medically significant scorpion species, with venoms containing potent neurotoxins that affect ion channels.
rake-legged mites
Caeculoidea is a superfamily of mites in the order Trombidiformes, containing the single family Caeculidae. These arachnids are commonly known as rake-legged mites due to their distinctive leg modifications. The group comprises approximately 9 genera and 100 described species with a worldwide distribution. Fossil evidence extends back to the Cenomanian (Late Cretaceous), with specimens preserved in Burmese amber.
Dyspnoan Harvestmen
Dyspnoi is a suborder of harvestmen (Opiliones) comprising approximately 43 extant genera and 356 described species across eight families. The group is organized into three superfamilies: Acropsopilionoidea, Ischyropsalidioidea, and Troguloidea. Dyspnoi represents one of the most biogeographically conserved higher groups of harvestmen, with distribution patterns suggesting relictual status as paleo-European mainland fauna. Members possess distinctive defensive scent glands with complex functional anatomy involving hidden ozopores and specialized secretion discharge mechanisms.
dwarf spiders
Entelecara is a genus of dwarf spiders (family Linyphiidae) described by Eugène Louis Simon in 1884. The genus contains 21 described species distributed across North America, Europe, Russia, Central Asia, China, Korea, Japan, and North Africa. Species within this genus are small-bodied spiders, consistent with the dwarf spider morphology characteristic of Linyphiidae. The type species is Entelecara acuminata.
dwarf spiders, money spiders
Erigoninae is the largest subfamily of Linyphiidae (sheet-web weavers), itself the second largest spider family. These minute spiders are commonly called dwarf spiders in the United States and money spiders in England. The subfamily contains over 2,000 described species, making it the most numerous group within the sheet-web weavers. Many species inhabit leaf litter and construct small sheet webs, while others occupy diverse terrestrial habitats from coastal dunes to alpine timberlines.
Escaphiella is a genus of dwarf goblin spiders in the family Oonopidae, established in 2009 by arachnologists Norman Platnick and Nadine Dupérré. The genus contains 36 described species distributed across the Americas, from the southwestern United States through Mexico, Central America, and into South America. Most species were described in the original 2009 revision, though some were transferred from other genera based on newly recognized morphological characters.
Eurybunus is a genus of harvestmen (Opiliones) in the family Globipedidae, established by Nathan Banks in 1893. The genus contains four described species: E. brunneus, E. pallidus, E. riversi, and E. spinosus. All species are endemic to the Western United States. Taxonomic placement has been disputed, with some sources historically placing the genus in Sclerosomatidae, though current consensus recognizes Globipedidae.
Eylaidae is a family of mites in the order Trombidiformes, suborder Prostigmata. The family contains at least one genus, Eylais, with approximately six described species. These mites are classified within the superfamily Eylaoidea and infraorder Anystina. The group is poorly studied, with limited published information on their biology and ecology.
Bowl and Doily Spiders
Frontinella is a genus of dwarf spiders in the family Linyphiidae, first described by F. O. Pickard-Cambridge in 1902. The genus contains nine described species distributed across China, El Salvador, Mexico, and the United States. The best-known member, F. communis (formerly F. pyramitela), is recognized by its distinctive bowl-and-doily web architecture. These spiders are small-bodied, with mature females measuring 3–4 mm. Some species exhibit behavioral thermoregulation through solar orientation and cohabitation behavior between males and females.
pseudoscorpions
Garypidae is a family of pseudoscorpions established by Eugène Simon in 1879. The family comprises eleven accepted genera, including the type genus Garypus. Members of this family are distributed across multiple continents, with records from Europe and elsewhere. The family belongs to the superfamily Garypoidea within the suborder Iocheirata.
House Jumping Spiders
Hasarius is a genus of jumping spiders (family Salticidae) containing 32 species as of October 2025. The genus was established by Simon in 1871. Species in this genus are commonly known as House Jumping Spiders. One species, H. neocaledonicus, was removed from Hasarius in 2008 and placed in its own genus, Rhondes.
Heteroonops is a genus of goblin spiders (family Oonopidae) described by Dalmas in 1916. The genus contains approximately 25 species as of 2021. These spiders are part of the diverse Oonopidae family, which are characterized by their small size and compact body form. Members of this genus are found in various regions, with distribution records including Denmark.
North American lampshade spiders
Hypochilus is a genus of North American lampshade spiders (family Hypochilidae) comprising eleven described species, all endemic to the United States. The genus is a relictual lineage with a disjunct distribution across three montane regions: California, the southern Rocky Mountains, and the southern Appalachia. Hypochilus species exhibit extreme genetic divergence coupled with striking morphological conservatism, creating persistent challenges for species delimitation. These spiders are textbook examples of short-range endemics with naturally small geographic ranges and strict microhabitat specialization.
Leptinae is a subfamily of mites in the family Erythraeidae, order Trombidiformes. These are prostigmatid mites, a group that includes many predatory and parasitic species. The subfamily was established by Billberg in 1820 and contains genera characterized by elongated body forms. Members of this subfamily are found across multiple continents, with over 3,000 observations recorded on iNaturalist.
Limnesiidae is a family of water mites (Prostigmata) within the order Trombidiformes. The family comprises at least 3 genera—*Limnesia*, *Centrolimnesia*, and *Tyrrellia*—with approximately 20 described species. Members of this family are aquatic arachnids associated with freshwater habitats.
Mygalomorphs, Orthognatha
Mygalomorphae is one of three major lineages of living spiders, comprising over 3,000 species across 32 families. Members include tarantulas, trapdoor spiders, and Australian funnel-web spiders. They are characterized by downward-pointing chelicerae, two pairs of book lungs, and often large body sizes with exceptional longevity—some individuals live 25 years or more. The group exhibits remarkable morphological conservatism across its global distribution.
dwarf sheet spiders
Neoantistea is a genus of dwarf sheet spiders in the family Hahniidae, established by Willis J. Gertsch in 1934. The genus contains approximately 25 species distributed across North America, Mexico, and parts of Asia. These spiders are characterized by their small size, with most adults under 4 mm in body length. Neoantistea is notable within the Hahniinae for being one of the few genera that constructs webs, unlike related genera such as Hahnia and Antistea.
cellar spiders, daddy long-legs spiders, carpenter spiders, vibrating spiders, gyrating spiders
Pholcidae is a large family of araneomorph spiders containing over 2,000 species across 94+ genera. Members are commonly known as cellar spiders or daddy long-legs spiders due to their extremely long, thin legs and tendency to inhabit dark, undisturbed spaces. The family exhibits remarkable diversity in habitat use, from caves and tropical forests to human dwellings, with some species showing specialized adaptations including troglomorphism and communal web-sharing. Several species have become globally distributed through human transport, notably Pholcus phalangioides.
Guardstone Spiders
Phrurolithidae is a family of araneomorph spiders commonly known as guardstone spiders. First described by Nathan Banks in 1892, the family was long treated as a subfamily (Phrurolithinae) within Corinnidae until phylogenetic studies established its separate family status. The family currently comprises 27 genera and approximately 421 species. Members are small to medium-sized spiders, predominantly found in the Northern Hemisphere with exceptional diversity in southern China, where many species are endemic to specific mountain localities.
Polyaspis is a genus of mesostigmatid mites in the family Polyaspididae. The genus contains approximately six described species distributed across multiple continents. These mites belong to the diverse order Mesostigmata, which includes many free-living and parasitic species.
Praestigia is a genus of sheet-weaving spiders (family Linyphiidae) described by Alfred Frank Millidge in 1954. The genus is distinguished by a unique male cephalic projection bearing a detachable cap composed of interconnected fibers bound with a waxy substance. Eight species are recognized, distributed across boreal and arctic regions of the Northern Hemisphere. The etymology combines Latin 'prae' (before/in front) and Greek 'stigios' (awl), referencing this distinctive projection.
Huntsman spiders, Giant crab spiders, Wood spiders
Sparassidae, commonly known as huntsman spiders or giant crab spiders, comprises a family of large, fast-moving araneomorph spiders distributed primarily in tropical and subtropical regions worldwide. Members are characterized by laterigrade legs—oriented horizontally to the body—that enable them to navigate narrow crevices and vertical surfaces with ease. The family includes both solitary and social species, with some genera exhibiting prolonged subsociality where females share retreats with multiple generations of offspring for extended periods. Several species are known to occasionally appear in temperate regions through human commerce, particularly in banana shipments.
prowling spiders
Syspira is a genus of prowling spiders in the family Miturgidae, first described by Simon in 1895. These active, nocturnal hunters are characterized by their leggy appearance and body lengths of 10–18 mm. The genus occurs in arid and semi-arid regions of the southwestern United States, Mexico, and the Caribbean, with highest diversity in western North America. Taxonomic revision is ongoing, with species historically placed in Clubionidae and some specimens of S. pallida potentially belonging to the unrelated genus Zorocrates.
Talanites is a genus of ground spiders in the family Gnaphosidae, established by Eugène Simon in 1893. The genus contains fifteen described species distributed across arid and semi-arid regions of North America, the Mediterranean, Central Asia, and South Asia. Members are ground-dwelling hunters with a flattened body form typical of the family. The genus shows a disjunct distribution pattern with species in both the New World and Old World.
Spider Mites
Tetranychidae is a family of mites commonly known as spider mites, comprising approximately 1,200 described species. Members are minute plant-feeding arachnids, typically measuring less than 1 mm in length. They are distributed worldwide and are significant agricultural pests, causing damage to hundreds of plant species by piercing leaf cells and extracting contents. Many species produce silk webbing for protection and dispersal. The family is divided into two subfamilies: Bryobiinae and Tetranychinae.
Trombidiform Mites
Trombidiformes is a large, diverse order of mites within the subclass Acariformes, comprising approximately 25,821 described species across 151 families. The order is divided into two suborders: Sphaerolichida (two families) and Prostigmata (the majority, with four infraorders and 40 superfamilies). Members include medically significant species such as Demodex mites, chiggers (Trombiculidae), and scrub-itch mites, as well as agriculturally important groups like spider mites (Tetranychidae). The phylogenetic placement of the superfamily Eriophyoidea (gall mites) remains uncertain; recent molecular analyses suggest it may fall outside Trombidiformes, possibly related to Nematalycidae.
Uropodella is a genus of mites in the family Uropodellidae, established by Berlese in 1888. The genus contains a single described species, Uropodella laciniata. These mites belong to the order Mesostigmata, a group of predatory or parasitic mites with diverse ecological roles.
Uropodellidae is a family of mites in the order Mesostigmata, suborder Sejida. These mites belong to the superfamily Sejoidea. The family is small and poorly documented, with limited biological and ecological data available. Members are known from scattered records, and their taxonomy and natural history remain incompletely studied.
dwarf spiders
Walckenaeria is a genus of dwarf spiders in the family Linyphiidae, first described by John Blackwall in 1833. The genus contains approximately 195-198 species as of 2020, distributed across multiple continents. Males in this genus exhibit distinctive eye morphology, with some species having eyes elevated on mounds, turrets, or stalks that can exceed the height of the carapace. Walckenaeria is a senior synonym of several previously described genera including Paragonatium, Wideria, and Cornicularia.
ground spider
Zelotes is a large genus of ground spiders in the family Gnaphosidae, with approximately 400 described species distributed worldwide. These small to medium-sized spiders (5-10 mm) are typically dark reddish brown to nearly black in color. They are characterized by distinctive eye arrangements and frequently display a pale patch on the inner surface of the first femur. The genus was first described by J. Gistel in 1848 and represents one of the most species-rich genera within the ground spider family.
Zora is a genus of small to medium-sized spiders in the family Miturgidae. These entelegyne, ecribellate spiders are characterized by two claws with claw tufts, distinct longitudinal bands on the cephalothorax, an 4-2-2 eye arrangement, and long overlapping spines on the first two tibiae and metatarsi. The genus contains 17 described species with abdomens showing distinct color patterns useful for species identification. The genus was established by C. L. Koch in 1847 and has historically been placed in the family Zoridae, though modern classifications assign it to Miturgidae.
False Wolf Spiders
Zoropsidae, commonly known as false wolf spiders, is a family of cribellate araneomorph spiders first described by Philipp Bertkau in 1882. The family includes approximately 180 species across 28 genera as of 2026. Members are wandering spiders that bear superficial resemblance to wolf spiders (Lycosidae) but are distinguished by their eye arrangement. The family has undergone taxonomic revision, with Tengellidae and Zorocratidae now included within Zoropsidae. One species, Zoropsis spinimana, has been introduced to the United States.