Theridiidae
Guides
Phylloneta pictipes
Phylloneta pictipes is a cobweb spider in the family Theridiidae, native to the United States. This species constructs irregular cobwebs for prey capture. Adults display distinctive coloration with a yellow abdomen bearing patterned black spots, black-banded legs, and a comparatively small cephalothorax. The species has been documented in 1,110 iNaturalist observations, indicating it is moderately well-recorded though not commonly encountered in general natural history.
Platnickina alabamensis
cobweb spider
Platnickina alabamensis is a species of cobweb spider in the family Theridiidae. It was originally described as Theridion alabamense by Gertsch and Archer in 1942. The species is native to North America.
Platnickina mneon
A comb-footed spider in the family Theridiidae, originally described from a female specimen collected in Saga Prefecture, Kyushu, Japan in 1906. The species was recently reinstated as valid based on distinct body coloration, markings, genital morphology, and molecular data (partial mitochondrial COI gene), having been previously synonymized with Yunohamella lyrica. Molecular analysis revealed that females previously identified as Platnickina mneon are conspecific with males associated with Yunohamella varietas, leading to the latter's synonymization. The species is currently classified under the genus Platnickina, though it was transferred to Yunohamella in the revision that reestablished its validity.
Robertus
Robertus is a genus of comb-footed spiders in the family Theridiidae. It was established by Octavius Pickard-Cambridge in 1879 and is recognized as the senior synonym of the former genus Garritus. The genus comprises small spiders that construct tangled, irregular webs. Species within Robertus are found primarily in the Northern Hemisphere, with documented occurrences in Europe and North America.
Robertus frontatus
cobweb spider
Robertus frontatus is a small cobweb spider in the family Theridiidae, first described by Nathan Banks in 1892. The species was originally placed in the genus Microneta before being transferred to Robertus. It is one of many understudied theridiid species with limited published biological information.
Robertus pumilus
Robertus pumilus is a species of cobweb spider in the family Theridiidae. It is found in the United States. The species was described by James Henry Emerton in 1909.
Simitidion
Simitidion is a genus of comb-footed spiders (Theridiidae) described by J. Wunderlich in 1992. The genus contains three recognized species: S. agaricographum, S. lacuna, and S. simile. Native populations occur in Africa, Asia, and Europe, with S. simile introduced to Canada. The genus is part of the diverse cobweb spider family.
Simitidion simile
Simitidion simile is a species of comb-footed spider in the family Theridiidae. Native to the Palearctic region, it has been documented across Europe, North Africa, Turkey, Israel, the Caucasus, Kazakhstan, Iran, and Central Asia. The species has been introduced to Canada, establishing populations outside its native range. As a member of the Theridiidae, it possesses the characteristic comb-like setae on the hind tarsi used for silk handling.
Spintharus
Spintharus is a genus of cobweb spiders (Theridiidae: Argyrodinae) established by Nicholas Marcellus Hentz in 1850. The genus ranges from the northeastern United States to Brazil, with the highest diversity in the Caribbean. A 2018 revision by Agnarsson and colleagues described fifteen new species, many named after celebrities and public figures, making Spintharus notable for having the most species named after celebrities of any spider genus. Molecular evidence indicates that what was historically considered a single widespread species, S. flavidus, actually represents a 30 million year old radiation of at least 16 short-range endemic species in the Caribbean region.
Spintharus flavidus
Spintharus flavidus is a cobweb spider in the family Theridiidae, historically considered a single widespread species ranging from northern North America to Brazil and throughout the Caribbean. Molecular phylogenetic analysis has rejected this hypothesis, revealing instead a 30 million year old radiation of at least 16 distinct species in the Caribbean region alone. Nearly all are short-range endemics with limited overwater dispersal ability. The Caribbean colonization event occurred approximately 30 million years ago, coinciding with the GAARLandia landbridge hypothesis.
Steatoda
False Widow Spiders, Cupboard Spiders
Steatoda is a genus of cobweb spiders in the family Theridiidae containing approximately 120 recognized species with worldwide distribution. Many species are synanthropic, commonly found in human dwellings, sheds, garages, and undisturbed corners. Members are frequently mistaken for widow spiders (Latrodectus) due to similar body shape and web structure, earning them the common name "false widows," though they are significantly less harmful to humans. The genus includes both native and invasive species, with Steatoda nobilis (Noble False Widow) being particularly notable for its rapid range expansion in Europe and North America.
Steatoda albomaculata
white-spotted false widow, white-spotted false widow spider
Steatoda albomaculata is a small cobweb spider in the family Theridiidae, commonly known as the white-spotted false widow. It is widely distributed across North America, Europe, Russia, North Africa, the Middle East, Central Asia, and East Asia. The species has been studied for its predation efficiency on various prey types and is recognized as a generalist predator. It was formerly considered to have two subspecies, but Steatoda albomaculata infuscata was synonymized with the nominate form in 2024, leaving no valid subspecies.
Steatoda castanea
Steatoda castanea is a cobweb spider in the family Theridiidae, closely related to black widows and other Steatoda species. It is native to the Palearctic region, with distribution records from Europe through Russia, the Caucasus, Iran, Central Asia, and China. The species has been introduced to North America, including Canada. As a member of the cobweb weaver family, it constructs irregular tangled webs and shares the general morphology and habits typical of the genus Steatoda, though specific behavioral and ecological details for this species remain poorly documented in available literature.
Steatoda erigoniformis
Steatoda erigoniformis is a cobweb spider in the family Theridiidae. Originally described from the East Mediterranean region, it has a broad native distribution spanning North Africa, the Middle East, Caucasus, and East Asia. The species has been introduced to multiple regions including the United States, Caribbean, Venezuela, Cape Verde, and South Africa, where it has established populations in agricultural and natural habitats. It constructs three-dimensional cobwebs in dark, sheltered locations and has been recorded from sea level to nearly 3,000 meters elevation.
Steatoda grandis
Steatoda grandis is a species of cobweb spider in the family Theridiidae, first described by Banks in 1901. It is known from the United States, though specific details about its biology and ecology remain poorly documented in the scientific literature. The species belongs to a genus that includes several well-known spiders, some of which are frequently encountered in human dwellings.
Steatoda hespera
Steatoda hespera is a species of cobweb spider in the family Theridiidae. It is native to North America and has been documented in the United States and Canada. As a member of the genus Steatoda, it belongs to a group commonly known as false widow spiders, though specific details about its biology and ecology remain limited in the available literature.
Steatoda mexicana
Steatoda mexicana is a cobweb weaver spider (family Theridiidae) described by Herbert W. Levi in 1957. It is native to Mexico and the southwestern United States. Like other Steatoda species, it constructs irregular tangled webs and is a member of the same genus as the well-known Triangulate Cobweb Weaver (S. triangulosa) and the Noble False Widow (S. nobilis). Very little specific information has been published about the biology of this particular species.
Steatoda palomara
Steatoda palomara is a species of cobweb spider in the family Theridiidae. It is known only from the United States, with records from North America. The species was described by Chamberlin & Ivie in 1935. Like other members of the genus Steatoda, it is presumed to construct irregular tangled webs typical of theridiid spiders.
Steatoda variata
Steatoda variata is a species of cobweb spider in the family Theridiidae, first described by Gertsch in 1960. It is found in the United States and Mexico. Two subspecies are recognized: Steatoda variata variata and Steatoda variata china. Very little is known about the specific biology or ecology of this species compared to better-studied congeners like Steatoda triangulosa or Steatoda nobilis.
Steatoda washona
Steatoda washona is a cobweb spider in the family Theridiidae, described by Gertsch in 1960. It belongs to a genus that includes several species commonly known as false widows due to their resemblance to black widows (Latrodectus). The species occurs in the southwestern United States and Mexico. Like other Steatoda species, it constructs irregular tangled webs and is typically found in sheltered microhabitats.
Stemmops
Stemmops is a genus of small comb-footed spiders (Theridiidae: Spintharinae) first described in 1894. The genus contains approximately 27 species, with the majority distributed in the Americas from the United States through Central America to Brazil, and a smaller number of species in East Asia including China, Japan, Korea, and Laos. One species, S. satpudaensis, has been recorded from India.
Stemmops bicolor
Stemmops bicolor is a small spider species in the family Theridiidae (cobweb spiders), first described by O. Pickard-Cambridge in 1894. The species is known from the Caribbean region and parts of Central and North America, with records from Cuba, Mexico, the Bahamas, and the southern United States through Panama. As a member of the genus Stemmops, it belongs to a group of theridiid spiders characterized by their compact body form and specialized web-building behavior.
Theridion
tangle-web spiders
Theridion is a large genus of tangle-web spiders (family Theridiidae) with nearly 600 described species distributed worldwide. The genus has historically served as a wastebasket taxon for theridiid species lacking a colulus that did not fit into other genera. Notable species include T. grallator, the Hawaiian happy face spider, recognized for its distinctive abdominal color patterns, and T. nigroannulatum, one of few spider species known to live in social groups and hunt cooperatively. Molecular studies have revealed that Theridion as traditionally defined is para- or polyphyletic, with Hawaiian representatives representing at least two independent colonization events from different continental sources.
Theridion agrifoliae
Theridion agrifoliae is a species of cobweb spider in the family Theridiidae, described by Levi in 1957. It is native to western North America, with records from the United States and Canada. Like other members of Theridiidae, it constructs irregular, three-dimensional webs to capture prey. The species epithet "agrifoliae" suggests an association with coast live oak (Quercus agrifolia), though specific ecological relationships remain poorly documented.
Theridion albidum
White Long-legged Cobweaver
Theridion albidum is a species of cobweb spider in the family Theridiidae, first described by Banks in 1895. It is native to North America and has been documented in the United States and Canada. As a member of the genus Theridion, it belongs to a large and diverse group of comb-footed spiders that construct irregular, three-dimensional webs. The species is known by the common name "White Long-legged Cobweaver," though detailed natural history information remains limited in published sources.
Theridion arizonense
Theridion arizonense is a species of cobweb weaver spider in the family Theridiidae, described by Herbert W. Levi in 1957. The specific epithet suggests an association with Arizona, though detailed information about this species remains limited in the available literature. As a member of the genus Theridion, it shares the general characteristics of small to medium-sized theridiid spiders that construct irregular, three-dimensional webs.
Theridion australe
Theridion australe is a cobweb spider species in the family Theridiidae, first described by Nathan Banks in 1899. The species is part of the large genus Theridion, which contains numerous small spiders that construct irregular, three-dimensional webs. It has been recorded across parts of the Americas including the United States, Mexico, and Caribbean regions. Like other theridiids, it possesses comb-like spines on the hind tarsi used to manipulate silk.
Theridion californicum
Theridion californicum is a species of cobweb spider in the family Theridiidae. It has been documented in the United States and Canada. As a member of the Theridiidae, it constructs irregular, three-dimensional webs for prey capture.
Theridion cheimatos
Theridion cheimatos is a cobweb spider species in the family Theridiidae. It was described by Gertsch and Archer in 1942. The species is known from the United States, with records from North America. As a member of Theridiidae, it constructs irregular three-dimensional cobwebs and possesses comb-footed spines on the hind legs for manipulating silk.
Theridion differens
Different Cobweb Spider
Theridion differens is a species of cobweb spider in the family Theridiidae. It is found in the United States and Canada, with records from Alberta and British Columbia. The species was described by Emerton in 1882. As a member of the genus Theridion, it constructs the irregular, three-dimensional webs characteristic of this group.
Theridion dilutum
Theridion dilutum is a species of cobweb spider in the family Theridiidae, described by Herbert W. Levi in 1957. It belongs to one of the largest genera of spiders, with members characterized by their irregular, three-dimensional webs. The species occurs in North America, specifically in the United States and Mexico. Like other theridiids, it possesses comb-like serrated bristles on the hind tarsi used to manipulate silk.
Theridion flavonotatum
Theridion flavonotatum is a species of cobweb spider in the family Theridiidae. The species is documented from the United States, Cuba, and Turks & Caicos. Like other members of the genus, it constructs irregular three-dimensional webs. Published information on its biology and ecology remains sparse.
Theridion frondeum
Eastern Long-legged Cobweaver
Theridion frondeum is a species of cobweb spider in the family Theridiidae, commonly known as the Eastern Long-legged Cobweaver. It is found in North America, with records from the United States, Canada, and the Bahama Islands. Like other members of Theridiidae, it constructs irregular three-dimensional webs and possesses comb-like structures on its hind legs for silk handling. The species was first described by Nicholas Marcellus Hentz in 1850.
Theridion goodnightorum
Theridion goodnightorum is a species of cobweb spider in the family Theridiidae, described by arachnologist Herbert W. Levi in 1957. The species epithet honors the husband-and-wife arachnologists Clarence and Marie Goodnight. Like other members of the genus Theridion, this species constructs irregular, three-dimensional cobwebs and possesses the characteristic comb-like bristles (setae) on the hind tarsi used to manipulate silk. The species is documented from the southwestern United States and Mexico.
Theridion kawea
Theridion kawea is a species of cobweb spider described by Herbert W. Levi in 1957. It belongs to the family Theridiidae, a large group of spiders characterized by their irregular, three-dimensional webs and comb-like structures on their hind legs used for silk manipulation. The species has been documented in the southwestern United States and Mexico.
Theridion lawrencei
Theridion lawrencei is a species of cobweb spider in the family Theridiidae, described by Gertsch and Archer in 1942. It is a small theridiid spider found in the United States. Like other members of its family, it constructs irregular, three-dimensional tangled webs. The species is named in honor of someone (likely R.F. Lawrence, a notable arachnologist), though the specific etymology is not documented in available sources. Very little detailed biological information has been published about this species specifically.
Theridion melanurum
Theridion melanurum is a cobweb spider in the family Theridiidae, first described by Hahn in 1831. The species has a broad Palearctic distribution spanning Europe to Siberia, with additional populations in Macaronesia, North Africa, and the Middle East. It has been introduced to the United States, where established populations have been documented. As a member of Theridiidae, it constructs the irregular, three-dimensional webs characteristic of cobweb spiders.
Theridion michelbacheri
Theridion michelbacheri is a species of cobweb spider in the family Theridiidae, first described by Levi in 1957. It is known from the United States, with records indicating presence in North America. As a member of the genus Theridion, it shares the general characteristics of this large and diverse group of comb-footed spiders, though specific details about its biology remain poorly documented.
Theridion morulum
Theridion morulum is a species of cobweb spider in the family Theridiidae, first described by O. Pickard-Cambridge in 1898. It belongs to a large genus of small spiders known for their irregular, three-dimensional webs. The species is recorded from the southwestern United States and Mexico, but detailed biological information appears limited in available sources.
Theridion murarium
Fence Long-legged Cobweaver
Theridion murarium is a species of cobweb spider in the family Theridiidae, first described by Emerton in 1882. It is found in North America, with records from the United States, Canada (including Alberta), and Middle America. Like other Theridiidae, it constructs irregular, three-dimensional webs. The common name 'Fence Long-legged Cobweaver' suggests an association with fence-line habitats, though specific ecological details remain poorly documented.
Theridion neomexicanum
Theridion neomexicanum is a species of cobweb spider in the family Theridiidae. It is found in the United States and Canada. As a member of the Theridiidae, it constructs irregular, three-dimensional webs typical of the family. The species was described by Banks in 1901.
Theridion neshamini
Theridion neshamini is a species of cobweb spider in the family Theridiidae, described by Levi in 1957. The species is known from the United States, though specific details about its biology, habitat preferences, and ecology remain poorly documented. As a member of Theridiidae, it is presumed to construct irregular, three-dimensional cobwebs for prey capture.
Theridion pennsylvanicum
Theridion pennsylvanicum is a cobweb spider in the family Theridiidae, described by Emerton in 1913. It belongs to the infraorder Araneomorphae, the true spiders. The species is known from the United States and Canada. Like other members of Theridiidae, it constructs irregular, three-dimensional webs and possesses the comb-like spines on the hind legs characteristic of this family.
Theridion petraeum
Theridion petraeum is a cobweb spider in the family Theridiidae, described by L. Koch in 1872. The species has a broad distribution spanning North America, Europe, North Africa, the Caucasus, and Russia extending to the Far East and Kazakhstan. Records indicate presence across multiple continents including Africa and northern Asia. As a member of Theridiidae, it constructs irregular three-dimensional webs, though specific details of its biology and ecology remain poorly documented in available sources.
Theridion pictum
Painted Cobweb Weaver
Theridion pictum is a cobweb spider in the family Theridiidae and the type species of the genus Theridion. It has a Holarctic distribution spanning North America, Europe, and Asia, with introduced populations in South Africa. The species constructs three-dimensional webs in damp, low-lying areas, often on vegetation or man-made structures. Adults mature in early to mid-summer, with females persisting into autumn.
Theridion pierre
Theridion pierre is a species of cobweb spider in the family Theridiidae, described by Levi & Patrick in 2013. It is a member of the large genus Theridion, which contains numerous small spiders that construct irregular, three-dimensional webs. The species is known from the United States.
Theridion rabuni
Theridion rabuni is a species of cobweb spider in the family Theridiidae. It is known from the United States and the Bahama Islands. Little specific information is available about its biology, ecology, or behavior beyond its taxonomic placement and geographic distribution.
Theridion submissum
Theridion submissum is a species of cobweb spider in the family Theridiidae. The species was described by Gertsch and Davis in 1936. It is found in the United States, Mexico, the Bahama Islands, and Jamaica. Like other members of the genus Theridion, it constructs irregular three-dimensional webs.
Theridion transgressum
Theridion transgressum is a species of cobweb spider in the family Theridiidae, first described by Petrunkevitch in 1911. It belongs to the large genus Theridion, which contains numerous small-bodied spiders that construct irregular, three-dimensional webs. The species is recorded from the United States and Mexico. Very little specific biological information is available for this species.
Theridion varians
Variable Cobweb Spider
Theridion varians is a species of cobweb spider in the family Theridiidae. It has a broad native distribution spanning Europe, North Africa, Turkey, the Caucasus, Russia, Central Asia, and China. The species has been introduced to North America, where it is now established in Canada and the United States. Four subspecies are recognized, reflecting geographic variation across its range.