Araneus partitus is a species of orb-weaver spider in the family Araneidae. It is known to occur in the United States, though specific details about its biology and ecology remain poorly documented. The species was described by Walckenaer in 1841. Like other members of the genus Araneus, it constructs spiral orb webs for prey capture.
Redlined Wolf Spider
Arctosa rubicunda is a wolf spider in the family Lycosidae, commonly known as the Redlined Wolf Spider. It occurs in North America, with confirmed records from the United States and Canada including Alberta and British Columbia. The species has been documented as a host for the spider wasp Priocnemis minorata, which paralyzes it to provision nests for its larvae.
Arcuphantes arcuatulus is a species of sheetweb spider in the family Linyphiidae. It was described by Roewer in 1942 and is known from the United States and Canada. Members of this family construct small, flat sheet webs to capture prey.
Plump Dictynid Spider
Argenna obesa is a small spider in the family Dictynidae, described by Emerton in 1911. It is known from prairie and grassland regions of central North America. The species is characterized by a notably plump, rounded abdomen that distinguishes it from related dictynid spiders. Records indicate it occurs in the Canadian prairies and north-central United States. Very little is known of its biology or ecological role.
dew-drop spider, American Dewdrop Spider
Argyrodes elevatus is a kleptoparasitic spider in the family Theridiidae that steals food from the webs of other spiders rather than building its own. Adults measure 4–7 mm in length, with males smaller than females. The species exhibits specialized adaptations for stealth, including vibrational detection of host activity, rapid prey theft completed in under 12 seconds, and nocturnal activity patterns that oppose those of diurnal host species. Courtship involves males presenting silk-wrapped prey as nuptial gifts to females.
giant daddy-long-legs spider, Giant Cellar Spider
Artema atlanta is a large cellar spider and the largest known pholcid, with a body length of 8–11 mm. It has a pantropical distribution and has been introduced to temperate regions including North America and Europe. The species is commonly known as the giant daddy-long-legs spider. It constructs tangled webs in dark, sheltered locations and exhibits characteristic pholcid behavior of rapid, vibrating movement when disturbed.
Attidops cutleri is a small jumping spider in the family Salticidae, first described by Edwards in 1999. The species is known from limited observations, with only 8 documented records on iNaturalist. It occurs in the southern United States and Mexico. Like other salticids, it possesses excellent vision and hunts by stalking prey rather than building webs.
Attulus finschi is a species of jumping spider in the family Salticidae. It occurs across northern regions of North America and Eurasia, with documented populations in Russia (from West Siberia to the Far East), Canada, and the United States. As a member of the Attulus genus, it shares the characteristic jumping ability and visual acuity typical of salticid spiders.
long-jawed orb-weavers
Azilia is a genus of long-jawed orb-weavers in the spider family Tetragnathidae, first described by Eugen von Keyserling in 1881. It is a senior synonym of Cardimia. The genus contains eleven recognized species distributed across the Americas, from the southern United States through Central America to South America, plus the Caribbean islands of Cuba and Saint Vincent and the Grenadines.
Azilia affinis is a species of long-jawed orb-weaver spider in the family Tetragnathidae. It was described by O. Pickard-Cambridge in 1893. The species occurs from the southern United States through Central America to Panama. Like other members of Tetragnathidae, it possesses elongated chelicerae (jaws) adapted for capturing prey while building orb-shaped webs.
Barronopsis floridensis is a funnel weaver spider in the family Agelenidae, originally described from Florida. It belongs to the large-bodied B. texana species group, characterized by robust morphology and distinct genitalic structures. Phylogenetic analysis places it in a clade with B. arturoi, sister to a clade containing B. texana and B. jeffersi. The species has been documented in the southeastern United States and the Bahama Islands.
Barronopsis texana is a species of funnel weaver spider in the family Agelenidae. It belongs to the large-bodied B. texana species group, characterized by distinctive genital morphology and larger body size relative to congeners. The species has been recorded across the United States with over 1,500 observations documented.
Utah Crab Spider
Bassaniana utahensis is a crab spider species in the family Thomisidae, commonly known as the Utah Crab Spider. It is native to western North America, occurring in Canada and the United States. As a member of the bark crab spider genus Bassaniana, it is typically associated with trees and woody vegetation where it employs ambush predation. The species was first described by Gertsch in 1932.
Multicolored Bark Crab Spider
Bassaniana versicolor is a crab spider in the family Thomisidae, native to North America. Females reach 6.75 mm in length, while males are smaller at 3.8–4.5 mm. The species exhibits color variation with a brown body marked by white spots. It is commonly known as the Multicolored Bark Crab Spider.
dwarf spiders, sheetweb weavers
Bathyphantes is a genus of dwarf spiders (family Linyphiidae) comprising approximately 57 species distributed across the Holarctic region, with additional species in South America, Africa, Asia, and Oceania. These small spiders construct sheet webs and are characterized by complex male pedipalps and female epigyna used for species identification. The genus was first described by Anton Menge in 1866. At least one species, Bathyphantes simillimus, exhibits a triennial life cycle potentially adapted to cooler environments.
Notch-tipped Shield Sheetweaver
Bathyphantes alboventris is a small sheetweb spider in the family Linyphiidae, first described by Banks in 1892. It is known from the United States and Canada. The species belongs to a genus of sheetweb weavers characterized by specific male genitalia structures. Limited information exists on its natural history and ecology.
Grey Sheetweb Weaver
Bathyphantes brevipes is a species of sheetweb spider in the family Linyphiidae, commonly known as the Grey Sheetweb Weaver. It is a small arachnid found across northern North America, with records from the United States and Canada including Alberta, British Columbia, and Manitoba. As a member of the Linyphiidae family, it constructs flat sheet webs typically positioned close to the ground or substrate.
Short Sheetweb Weaver
Bathyphantes brevis is a species of sheetweb spider in the family Linyphiidae, first described by Emerton in 1911. It is found in the United States and Canada. As a member of the Linyphiidae, it constructs flat, horizontal sheet webs. The species is part of the diverse genus Bathyphantes, which contains numerous small-bodied spiders.
Canada Sheetweb Weaver
Bathyphantes canadensis is a small sheetweb weaving spider in the family Linyphiidae, found across northern North America and eastern Russia. It is one of approximately 4,000 species in the sheetweb weaver family, characterized by their flat, horizontal web architecture. The species is rarely encountered by casual observers due to its small size and cryptic habits.
Hump-headed Shield Sheetweaver
Bathyphantes keeni is a species of sheetweb spider in the family Linyphiidae. It occurs in Canada and the United States. The species is part of the diverse sheetweb weaver group, which constructs flat or dome-shaped webs rather than orb webs. Little specific information has been published on its biology.
Short Shield Sheetweaver
Bathyphantes orica is a species of sheetweb spider in the family Linyphiidae, commonly known as the Short Shield Sheetweaver. It was described by Ivie in 1969. The species is known from the United States and Canada, though specific details about its biology remain poorly documented. Like other members of the genus Bathyphantes, it constructs sheet-like webs rather than orb webs.
Wide Shield Sheetweaver
Bathyphantes weyeri is a species of sheetweb spider in the family Linyphiidae, first described by Emerton in 1875. It belongs to a genus of small spiders that construct flat, horizontal sheet webs often accompanied by a dome-shaped retreat. The species is known from the United States, though specific details about its biology and ecology remain poorly documented. Like other linyphiids, it is presumed to be a small-bodied spider that occupies ground-level or low vegetation habitats.
Beata is a genus of jumping spiders (family Salticidae) found in North and South America. The genus was established by G. W. Peckham and E. G. Peckham in 1895. As members of the jumping spider family, species in this genus possess the characteristic large anterior median eyes and salticid locomotion patterns. The genus has accumulated 578 observations on iNaturalist, indicating moderate documentation of its occurrence.
Blabomma californicum is a species of true spider first described by Simon in 1895. It belongs to the family Cybaeidae (previously placed in Dictynidae). The species is notable for having only six eyes rather than the typical eight eyes found in most spiders. It occurs in western North America across Canada, the United States, and Mexico, and is listed as imperiled in Canada.
funnel weavers
Calilena is a genus of North American funnel-web spiders in the family Agelenidae. The genus was established in 1941 and currently contains 21 recognized species distributed primarily across the western and southwestern United States, with some species extending into Mexico. These spiders construct sheet-like webs with funnel-shaped retreats and are characterized by long spinnerets held parallel to each other.
Callilepis gosoga is a species of ground spider in the family Gnaphosidae, first described by Chamberlin & Gertsch in 1940. It is known from the United States. Like other members of its genus, it belongs to a group of ornate gnaphosids that share superficial similarities with the more extensively studied genus Sergiolus.
Ground spider
Callilepis imbecilla is a species of ground spider in the family Gnaphosidae. It occurs in the United States and Canada. Like other members of its genus, it is an ornate, colorful spider related to the more commonly observed Sergiolus. The species is poorly documented in scientific literature and field observations.
hacklemesh weaver
Callobius nomeus is a species of hacklemesh weaver spider in the family Amaurobiidae. It occurs in the United States and Canada, where it has been observed in association with tree bark. As a member of Amaurobiidae, it likely constructs tangled, mesh-like webs typical of the family. The species was first described by Chamberlin in 1919.
Callobius pictus is a hacklemesh weaver spider in the family Amaurobiidae. It occurs in the United States and Canada. As a member of the genus Callobius, it belongs to a group of spiders known for constructing tangled, mesh-like webs.
basket-web weavers
Calymmaria is a genus of small North American spiders known for their distinctive inverted cone-shaped webs. These araneomorph spiders were first described in 1937 and contain 31 species, with most distributed along the Pacific coast of the United States and Canada. They are primarily nocturnal and construct unique 'basket' webs under bark, rocks, and other sheltered substrates.
Calymmaria californica is a species of true spider in the family Cybaeidae. It was described by Nathan Banks in 1896. The species is found in the United States, though specific details about its biology and ecology remain poorly documented in published literature.
Calymmaria emertoni is a small true spider in the family Cybaeidae (formerly Hahniidae). It is one of approximately 31 Calymmaria species found north of Mexico, with most species restricted to the Pacific coast region. This species is notable for its distinctive basket-shaped web and nocturnal habits.
Calymmaria persica is a species of true spider in the family Cybaeidae, found in the United States. It belongs to the marronoid clade, a diverse group of small to medium-sized spiders united by genetic rather than obvious morphological characteristics. The species constructs distinctive basket-shaped webs and is primarily nocturnal.
Calymmaria suprema is a species of true spider in the family Cybaeidae, first described by Chamberlin and Ivie in 1937. It belongs to the genus Calymmaria, which contains 31 species north of Mexico, most restricted to the Pacific coast region. The species occurs in the United States and Canada, though specific details about its biology remain limited in published literature.
Canalidion montanum is a small tangle-web spider (family Theridiidae) and the sole species in the monotypic genus Canalidion. Originally described as Theridion montanum by James Emerton in 1882, it was transferred to its own genus by J. Wunderlich in 2018 based on distinctive cheliceral dentition and male genitalic morphology. The species has a holarctic distribution, occurring across northern North America and Eurasia.
Prairie Ant-mimic Sac Spider
Castianeira alteranda is a species of ant-mimic spider in the family Corinnidae. It occurs in the northern United States and southern Canada, with records from Alberta, Manitoba, and Saskatchewan. The species was described by Gertsch in 1942. Like other members of the genus Castianeira, it exhibits ant-mimicry as a defensive strategy.
Castianeira athena is a species of ant-mimic spider in the family Corinnidae, first described by Reiskind in 1969. Like other members of its genus, it exhibits Batesian mimicry of ants as a defensive strategy against predators. The species occurs in the United States and Mexico. As a corinnid spider, it is an active hunter rather than a web-builder.
Red-spotted Ant-mimic Sac Spider, Red Stripe Spider
Castianeira crocata is a small ant-mimic spider in the family Corinnidae, first described by Nicholas Marcellus Hentz in 1847. It is found in the United States. The species has a black body with distinctive red dorsal markings, a color pattern that can lead to misidentification as a black widow spider despite its very different body shape. Like other Castianeira species, it exhibits ant-mimicry behaviors and morphology.
Castianeira crucigera is a species of ant-mimic spider in the family Corinnidae, found in the United States. Like other members of its genus, it exhibits ant-mimicry morphology and behavior. The species is poorly documented in the scientific literature compared to congeners such as C. cingulata.
Castianeira dorsata is a species of true spider in the family Corinnidae, first described by Banks in 1898. It is distributed across the United States and Mexico. Like other members of its genus, it is an ant-mimicking spider, though specific behavioral and ecological details for this species remain poorly documented.
Castianeira thalia is a species of ant-mimic spider in the family Corinnidae, first described by Reiskind in 1969. It belongs to a genus known for ant-mimicry, where spiders resemble ants in appearance and behavior to avoid predation. The species has been documented in the western United States, particularly along the West Coast.
Variegated Ant-mimic Sac Spider
Castianeira variata is an ant-mimicking spider in the family Corinnidae, found in North and Central America. Females typically measure 7–9 mm in body length and are larger than males. The species exhibits Batesian mimicry of ants, particularly carpenter ants, as a defense strategy against predators. It is similar in general appearance to C. longipalpus and can be distinguished by specific coloration and pattern details.
Castianeira walsinghami is a species of true spider in the family Corinnidae. It occurs in the United States and Canada. Beyond basic taxonomic placement and geographic distribution, detailed natural history information for this specific species is limited in available sources.
Centromerita bicolor is a species of sheetweb spider in the family Linyphiidae, first described by John Blackwall in 1833. It is a small spider with a trans-Palearctic native distribution and has been introduced to North America. The species is known to occur in a variety of habitats across its range. Like other linyphiids, it constructs sheet webs for prey capture.
dwarf spiders
Centromerus is a genus of dwarf spiders in the family Linyphiidae, containing approximately 88 species and two subspecies. The genus has a broad distribution spanning the Holarctic region, with species recorded across Europe, North America, Asia, and North Africa. Many species exhibit restricted geographic ranges, while a few such as C. sylvaticus have exceptionally wide distributions. The genus was established by Dahl in 1886.
Centromerus persolutus is a species of sheetweb spider (family Linyphiidae) described by O. Pickard-Cambridge in 1875. It is a small-bodied spider that constructs flat, sheet-like webs to capture prey. The species occurs in northeastern North America, with documented records from the United States and Canada.
sheetweb spider, money spider
Centromerus sylvaticus is a small sheetweb spider in the family Linyphiidae, commonly known as money spiders. The species has a broad Holarctic distribution spanning North America, Europe, and Asia. Adults measure 2.2–4 mm in body length. Two subspecies are recognized: the nominate C. s. sylvaticus and C. s. paucidentatus described from Bulgaria.
dwarf spiders
Ceraticelus is a genus of dwarf spiders in the family Linyphiidae, subfamily Erigoninae. First described by Eugène Louis Simon in 1884, the genus currently contains approximately 34 species and two subspecies distributed primarily in North America, with some species occurring in Europe and Asia. The genus definition has been historically problematic due to superficial treatment of male palpal bulb morphology. Recent taxonomic work has clarified diagnostic characters through examination of the type species, C. fissiceps.
Thick-headed Dwarf Weaver
Ceraticelus crassiceps is a dwarf spider in the family Linyphiidae, described by Chamberlin and Ivie in 1939. It belongs to the subfamily Erigoninae, commonly known as dwarf spiders or money spiders. The species occurs in North America, with records from the United States and Canada.
dwarf spider
Ceraticelus fissiceps is a species of dwarf spider in the family Linyphiidae. It serves as the type species for the genus Ceraticelus, and examination of its specimens has been used to establish a formal definition of the genus. The species is found in the United States and Canada, with records from multiple provinces across Canada including Alberta, British Columbia, and Manitoba. As a sheet-web weaving spider in the Linyphiidae family, it likely constructs small horizontal webs in vegetation.