dwarf spider
Ceraticelus minutus is a species of dwarf spider in the family Linyphiidae, first described by James Henry Emerton in 1882. It is one of the smallest North American spiders, typically measuring only 1–2 mm in body length. The species is distributed across the United States and Canada, with records from provinces including Alberta, Manitoba, and Ontario. Like other linyphiids, it constructs small sheet webs close to the ground in vegetation.
dwarf spider
Ceraticelus similis is a species of dwarf spider in the family Linyphiidae, first described by Nathan Banks in 1892. It belongs to a diverse family of small spiders commonly known as sheet-web weavers or money spiders. The species is known from the United States and has been recorded in Alberta, Canada.
dwarf spiders
Ceratinella is a genus of dwarf spiders in the family Linyphiidae, first described by James Henry Emerton in 1882. As of January 2026, the genus comprises 28 recognized species. Members are morphologically similar to the related genera Ceraticelus and Idionella, and taxonomic revisions affecting these groups are anticipated.
Ceratinopsidis formosa is a species of dwarf spider in the family Linyphiidae. It is the sole member of its genus, which was established by Bishop and Crosby in 1930. The species was originally described by Banks in 1892. Very little is known about its biology or ecology.
dwarf spider
Ceratinopsis interpres is a species of dwarf spider in the family Linyphiidae, first described by O. Pickard-Cambridge in 1874. It belongs to a genus of small sheet-web weavers. The species is known from limited observations in the United States.
dwarf spider
Ceratinopsis nigriceps is a dwarf spider species in the family Linyphiidae, first described by Emerton in 1882. The species is recorded from the United States and Canada. Members of this family are generally small-bodied spiders that construct sheet webs or occupy ground layer habitats. Available information for this species is limited.
Ceratinopsis nigripalpis is a species of dwarf spider in the family Linyphiidae, first described by Emerton in 1882. It is one of numerous small-bodied spiders in the genus Ceratinopsis, which are characterized by their sheet-web building behavior. The species is known from the United States and Canada.
Carmine Orbweaver
Cercidia prominens is a small orb-weaver spider (family Araneidae) known for its distinctive brick-red to orange coloration. Females measure 3.8–5.4 mm in body length, with males slightly smaller at 3.6–4.1 mm. The species was first described by Niklas Westring in 1851 and underwent several taxonomic revisions before receiving its current name from Tamerlan Thorell in 1869. It occupies a broad geographic range across the Northern Hemisphere.
Cesonia is a genus of ground spiders in the family Gnaphosidae, first described by Eugène Simon in 1893. The genus contains 31 species distributed across North America, the Caribbean, and parts of the Mediterranean. Despite their common name as "ground spiders," many species are frequently found on vegetation and in arboreal habitats. Cesonia bilineata, the type species, has been documented engaging in predation on spiderlings of other spider species.
Two-lined Stealthy Ground Spider
Cesonia bilineata is a small ground spider in the family Gnaphosidae, first described by Nicholas Marcellus Hentz in 1847. Despite its common name suggesting terrestrial habits, this species is frequently observed climbing vegetation and scaling walls. It has been documented preying on spiderlings of other spider species, including in nursery webs of Pisaurina mira and Peucetia viridans. The species is widespread in eastern North America.
ground spider
Cesonia classica is a ground spider in the family Gnaphosidae, first described by Chamberlin in 1924. The species occurs in the southern United States and Mexico. Like other members of the genus Cesonia, it belongs to a group of active hunting spiders that do not build webs to capture prey. The genus Cesonia includes species that have been documented exhibiting predatory behavior toward other spiders, including raiding nursery webs to feed on spiderlings.
Cesonia gertschi is a species of ground spider in the family Gnaphosidae, described by Platnick & Shadab in 1980. It is distributed across the United States and Mexico. Like other members of its genus, it is a small, agile hunter. Specific details about its biology and ecology remain poorly documented.
ground spider
Cesonia rothi is a species of ground spider in the family Gnaphosidae, described by Platnick & Shadab in 1980. It is known from the United States. As a member of the Cesonia genus, it is presumed to share traits with congeners such as Cesonia bilineata, including small body size, arboreal habits despite the "ground spider" common name, and potential predation on other spiders including spiderlings.
Cesonia ubicki is a species of ground spider in the family Gnaphosidae, described by Platnick and Shadab in 1980. The species is distributed across the southwestern United States and Mexico. Like other members of the genus Cesonia, it is a small, agile predator. Specific details about its ecology and behavior remain poorly documented in the scientific literature.
Longlegged Sac Spiders, Yellow Sac Spiders
Cheiracanthium is a genus of araneomorph spiders in the family Cheiracanthiidae, first described by Carl Ludwig Koch in 1839. Commonly known as longlegged sac spiders or yellow sac spiders, the genus contains over 230 accepted species. These spiders are notable for their pale coloration, nocturnal hunting behavior, and habit of constructing silken retreats rather than permanent webs. They are frequently encountered in human dwellings, particularly in temperate regions, and have been the subject of controversy regarding their medical significance.
black-footed yellow sac spider, American yellow sac spider, Agrarian Sac Spider
Cheiracanthium inclusum is a small, pale yellow spider native to the Americas, commonly known as the black-footed yellow sac spider or American yellow sac spider. It is an active nocturnal hunter that does not construct webs to capture prey, instead relying on speed and agility to pursue arthropods. The species builds small silk retreats during daylight hours and is frequently encountered both in natural vegetation and human dwellings. Despite historical misconceptions, its bite produces only localized symptoms without necrosis.
Northern Yellow Sac Spider, Long-legged Sac Spider
Cheiracanthium mildei is a medium-sized spider native to Europe and North Africa, introduced to North America and parts of South America. Adults measure 7–10 mm in body length with pale green or tan coloration, darker palpi and chelicerae, and characteristically long front legs up to twice the length of others. It constructs silken retreats rather than capture webs, hunting actively at night. The species is frequently encountered in human dwellings, particularly in northern regions of its introduced range, and has been documented to bite humans with generally mild effects.
Chelicerates
Chelicerata is a major subphylum of arthropods characterized by the presence of chelicerae—pincer-like or fang-like appendages that are the first pair of structures before the mouth. The group includes horseshoe crabs, sea spiders, and arachnids (spiders, scorpions, mites, ticks, harvestmen, and allies). Chelicerates diverged from other arthropods by the mid-Cambrian period, approximately 508 million years ago. With over 77,000 described living species and estimates suggesting hundreds of thousands more undescribed species, chelicerates represent one of the most diverse animal groups after insects. Most living species are terrestrial air-breathers, though marine lineages persist.
Chrysso albomaculata is a species of comb-footed spider in the family Theridiidae, first described by O. Pickard-Cambridge in 1882. The species is documented from the United States, Caribbean islands, and Brazil. It belongs to a genus of small spiders often associated with leaf litter and vegetation in tropical and subtropical habitats. As with many Theridiidae, detailed natural history information remains limited.
cave meshweaver
Cicurina is a genus of small spiders commonly known as cave meshweavers, first described by Anton Menge in 1871. The genus has undergone multiple family reassignments, most recently placed in the family Cicurinidae in 2023. Species exhibit considerable size variation, with some measuring under 2 mm and others exceeding 13 mm. Many species are specialized cave dwellers (troglobites), including several federally endangered species in the United States.
Cicurina brevis is a small araneomorph spider species distributed across northern North America. A 2024 study identified this species as a potential subnivium specialist, exhibiting higher population densities beneath seasonal snowpack in winter than during summer months. This seasonal activity pattern suggests adaptation to cold-weather environments, distinguishing it from typical summer-active forest floor spiders.
Cicurina bryantae is a species of true spider in the family Cicurinidae, described by Exline in 1936. It is known only from the United States. The genus Cicurina includes species adapted to specialized habitats, with some congeners inhabiting caves or subnivium environments.
Cicurina intermedia is a species of true spider in the family Cicurinidae, first described by Chamberlin and Ivie in 1933. It belongs to a genus of small to medium-sized spiders known for their association with dark, humid microhabitats. The species has been recorded from the United States and parts of Canada.
Cicurina japonica is a spider species in the family Cicurinidae, originally described from Japan. It occurs naturally in Korea and Japan and has been introduced to parts of Europe, including Switzerland and Germany, though some European records are marked as doubtful. The species belongs to a genus that includes several cave-dwelling species, though specific habitat details for C. japonica itself are limited in available sources.
Cicurina pallida is a species of true spider in the family Cicurinidae, originally described by Keyserling in 1887. It is known from the United States. The genus Cicurina comprises small, pale spiders often associated with caves and subterranean habitats, though specific details about C. pallida's biology remain limited in published literature.
Cicurina pusilla is a small spider species in the family Cicurinidae, described by Simon in 1886. It is known from the United States, with six iNaturalist observations recorded. Like other members of the genus Cicurina, it is likely a ground-dwelling or cryptic species, though specific ecological details for this species remain poorly documented. The genus Cicurina includes several cave-dwelling specialists, though C. pusilla itself has not been documented as a cave obligate.
Cithaeron is a genus of small, nomadic spiders in the family Cithaeronidae. Members are characterized by depressed posterior median eyes and pseudosegmented tarsi. The genus includes species with Old World origins that have become established as human-mediated introductions in multiple regions, including the Americas. Cithaeron praedonius, the best-known species, was first documented in Florida in 2011 and has since been recorded in multiple counties.
Curly-legged Ground Spiders
Cithaeronidae is a small family of araneomorph spiders in the superfamily Gnaphosoidea, established by Simon in 1893. The family contains two genera—Cithaeron and Inthaeron—with approximately ten described species. Members are small, pale yellowish, fast-moving nocturnal hunters that construct silken retreats under rocks. Several species, notably Cithaeron praedonius, have been introduced to the Americas and Australia through human activity.
Citharoceps is a genus of tube-dwelling spiders in the family Segestriidae, established by Chamberlin in 1924. The genus contains two described species, both found in North America: C. fidicina (southern United States and Mexico) and C. cruzana (United States). These spiders are characterized by their elongated, cylindrical abdomens and six eyes arranged in three pairs, traits typical of their family.
Citharoceps fidicina is a tube-dwelling spider in the family Segestriidae, described by Chamberlin in 1924. The genus Citharoceps is endemic to the southwestern United States and Mexico. Segestriid spiders are characterized by their elongated, cylindrical abdomens and their habit of constructing silken retreats in crevices, under bark, or in other sheltered locations. Members of this family possess six eyes arranged in a distinctive semicircular pattern, a trait that distinguishes them from most other spider families which typically have eight eyes.
Cixius yufengi is a species of planthopper in the family Cixiidae, described by Tsaur in 1993. The species belongs to a genus of small, often inconspicuous insects that feed on plant sap. Very little specific information is available about this particular species.
Clubiona abboti is a species of sac spider in the family Clubionidae, found in the United States and Canada. It is a nocturnal hunter that does not construct webs to capture prey. The species was described by L. Koch in 1866 and includes two recognized subspecies: C. a. abboti and C. a. abbotoides.
Clubiona bishopi is a species of sac spider in the family Clubionidae, first described by Edwards in 1958. It occurs in the United States and Canada. As a member of the sac spider family, it likely constructs silken retreats rather than webs for prey capture, though specific behavioral observations for this species are limited.
Canada Sac Spider
Clubiona canadensis is a species of sac spider in the family Clubionidae, first described by Emerton in 1890. It is distributed across northern North America, with records from multiple Canadian provinces including Alberta, British Columbia, and Manitoba, as well as the United States. As a member of the sac spider family, it likely constructs silken retreats rather than prey-capture webs, though specific details of its biology remain poorly documented.
Clubiona janae is a species of sac spider in the family Clubionidae, described by Edwards in 1958. The genus Clubiona is characterized by the presence of a distinct groove in the center of the carapace and a tuft of curved setae on the front edge of the abdomen, features that distinguish it from the superficially similar genus Cheiracanthium. Like other sac spiders, members of this genus do not construct prey-capture webs but instead hunt actively on foot. They construct silken retreats or "sleeping bags" for shelter.
Johnson's Sac Spider
Clubiona johnsoni is a species of sac spider in the family Clubionidae, described by Gertsch in 1941. It is found in the United States and Canada, with records from Alberta, Manitoba, and Ontario in Canada. Like other members of the genus Clubiona, it is a nocturnal hunting spider that does not build webs to capture prey. The species is distinguished from similar genera by possessing a distinct groove in the center of its carapace and a tuft of curved setae on the front edge of the abdomen.
Clubiona maritima is a sac spider species in the family Clubionidae. It occurs across North America from Canada through the United States and into the Caribbean region. As a member of the sac spider group, it constructs silken retreats rather than prey-capture webs and hunts actively. The species was described by Ludwig Carl Christian Koch in 1867.
Clubiona moesta is a species of sac spider in the family Clubionidae, first described by Banks in 1896. It belongs to a family of wandering spiders that do not construct permanent webs for prey capture. The species has a documented distribution across North America and Asia, with records from the United States, Canada, and China. Like other sac spiders, it constructs temporary silken retreats for shelter rather than for prey capture.
European Sac Spider
Clubiona pallidula is a species of sac spider in the family Clubionidae. It is native to Europe, the Caucasus, Russia (extending to the Far East), and Central Asia, and has been introduced to North America. The species has been the subject of detailed morphological studies examining its genital anatomy and copulatory mechanics. Unlike some related spiders frequently found indoors, this species is primarily encountered in outdoor habitats.
Riparian Sac Spider
Clubiona riparia is a sac spider species in the family Clubionidae. It is known from a broad geographic range spanning northern Eurasia and North America. The specific epithet 'riparia' refers to its association with riparian habitats. Like other Clubiona species, it constructs silken retreats rather than prey-capture webs and hunts actively.
Clubiona saltitans is a sac spider in the family Clubionidae, described by Emerton in 1919. The species name "saltitans" (Latin for "jumping" or "dancing") may allude to its active movement. Sac spiders in this genus are wandering hunters that construct silken retreats rather than prey-capture webs. They are primarily nocturnal predators of small insects and other arthropods. The genus Clubiona is distinguished from similar sac spiders by the presence of a distinct groove in the center of the carapace and a tuft of curved setae on the front edge of the abdomen.
Clubiona trivialis is a small sac spider in the family Clubionidae, characterized by its reddish-brown coloration and holarctic distribution. Unlike the longlegged sac spiders in the genus Cheiracanthium (now Eutichuridae), which are frequently encountered indoors, Clubiona species are less commonly found inside human dwellings. Adults are present year-round and occupy exposed positions on low vegetation.
Coleosoma floridanum is a small cobweb spider in the family Theridiidae. The species has a broad native distribution across the Americas and has been introduced to multiple regions worldwide, including Europe, West Africa, and Pacific islands. It builds irregular, tangled webs characteristic of its family.
Coras aerialis is a species of funnel weaver spider in the family Agelenidae, first described by Muma in 1946. It is found in the United States, with records from Vermont and other eastern states. The species belongs to a genus of forest-dwelling spiders that construct funnel-shaped webs with multiple retreats, often in elevated positions or crevices.
Coras lamellosus is a species of funnel weaver spider in the family Agelenidae. It occurs in the United States, where it constructs funnel-shaped webs in sheltered locations. Like other members of the genus Coras, it builds webs with multiple retreats rather than a single retreat, a distinguishing feature of this group. The species was described by Keyserling in 1887.
Medicinal Funnel Weaver
Coras medicinalis is a funnel-weaving spider in the family Agelenidae, native to eastern North America. The species was first described in 1821 and has undergone extensive taxonomic revision, with its current placement in Coras established by Eugene Simon in 1898. It constructs distinctive funnel-shaped webs with multiple retreats, often in human-associated structures as well as natural forest habitats. The species acquired its name from historical medicinal use of its webs in fever treatments during the 1800s.
Coreorgonal bicornis is a species of sheet-web weaver spider in the family Linyphiidae, first described by Emerton in 1923. The genus Coreorgonal belongs to a large family of small spiders commonly known as money spiders or sheet-web weavers, which construct horizontal sheet webs often with a retreat at one edge. The specific epithet "bicornis" (Latin for "two-horned") likely refers to a morphological feature of this species, though detailed descriptions of its appearance remain limited in available literature.
Cryphoeca is a genus of small araneomorph spiders first described by Tamerlan Thorell in 1870. The genus name derives from Greek meaning "hidden," reflecting its reclusive habits beneath loose bark and within stone walls. The genus contains twelve described species with a Holarctic distribution spanning North America, Europe, and Asia. Cryphoeca species are nocturnal and among the larger members of their subfamily, reaching nearly eight millimeters in body length.
Cryphoeca montana is a species of true spider in the family Cybaeidae, originally described by Emerton in 1909. It is a nocturnal spider belonging to the subfamily Cryphoecinae, which was historically classified within the family Hahniidae. The species occurs in forested habitats of the United States and Canada, where it has been documented from under bark on dead trees, in leaf litter, moss, and beneath stones.
Ctenus valverdiensis is a species of wandering spider in the family Ctenidae, described by Peck in 1981. It belongs to a genus known for active hunting behavior rather than web-building. The species has been documented in the United States, with observations recorded on iNaturalist. As with many Ctenidae, it likely exhibits cursorial habits and nocturnal activity patterns.