Araneae
Guides
Piratula insularis
Lonely Wolf Spider
Piratula insularis is a wolf spider (family Lycosidae) found across northern regions of North America and Eurasia. First described by Emerton in 1885 under the name Pirata insularis, this species has since been reclassified to the genus Piratula. The species epithet "insularis" (meaning "of islands") likely refers to its occurrence on islands or isolated habitats, though the original description context is not preserved in available sources. It is one of several species in the genus Piratula, which comprises small to medium-sized wolf spiders often associated with wetland and riparian habitats.
Platycryptus arizonensis
Platycryptus arizonensis is a species of jumping spider in the family Salticidae. It is found in the United States, with records indicating presence in North America. The species belongs to a genus of jumping spiders characterized by their flattened body form and cryptic coloration.
Psilochorus californiae
Psilochorus californiae is a species of cellar spider in the family Pholcidae. It was described by Chamberlin in 1919. The species occurs in the southwestern United States and Mexico. Like other pholcids, it constructs irregular, three-dimensional webs in dark, sheltered locations.
Psilochorus rockefelleri
A species of cellar spider in the family Pholcidae, described by Gertsch in 1935. The species belongs to a genus characterized by long, delicate legs and small, elongated bodies typical of pholcid spiders. Very little specific information has been published about this particular species beyond its original description and taxonomic placement.
Rhysodromus alascensis
Rhysodromus alascensis is a species of running crab spider in the family Philodromidae. It has a broad transcontinental distribution spanning northern North America and Eurasia, including Alaska, Siberia, Kazakhstan, and China. The species was originally described as Philodromus alascensis by Keyserling in 1884 and later transferred to the genus Rhysodromus. Like other philodromids, it is an active hunter that does not build webs to capture prey.
Saltonia incerta
Rare sheet-web-weaving spider, sole representative of monotypic genus Saltonia. Restricted to salt crusts of intermittent or dry lakes, streams, and rivers in desert southwestern North America. Previously presumed extinct following 1905 flooding of type locality at Salton Sea, but rediscovered in 1990s at multiple sites. Genetic analyses reveal significant population structure with two major clades (New Mexico versus California-northern Baja California) and minimal gene flow among isolated populations in fragmented desert salt flat habitats.
Schizocosa maxima
Scytodes
spitting spiders
Scytodes is a globally distributed genus of spitting spiders distinguished by their unique prey-capture mechanism: projecting a sticky, glue-like secretion from their fangs to immobilize prey. The genus contains approximately 239 species, with Scytodes thoracica being the most widely distributed. Members exhibit diverse social structures ranging from solitary to communal-territorial and fully social species.
Socalchemmis
false wolf spiders
Socalchemmis is a genus of spiders in the family Zoropsidae, first described by Norman I. Platnick and D. Ubick in 2001. The genus name derives from "Southern Californian Chemmis," reflecting its original discovery in California. The genus contains seventeen described species distributed in the southwestern United States and Mexico, with most species described from California localities. These spiders are commonly referred to as false wolf spiders due to their resemblance to true wolf spiders (Lycosidae).
Sparassidae
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.
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.
Symphytognathidae
dwarf orbweavers, micro orb-weavers
Symphytognathidae is a family of extremely small spiders (body size typically 1 mm or less, with Patu digua at 0.37 mm among the smallest known spiders). The family contains approximately 105 species in ten genera, including Crassignatha, Patu, Anapistula, and Micropholcomma. Members construct minute orb webs, often suspended between dead leaves in leaf litter or between vegetation. The family was historically placed in various superfamilies but molecular phylogenetics supports placement within Araneoidea, with affinities to Theridiosomatidae and Anapidae.
Tapinesthis inermis
Tapinesthis inermis is a minute spider species in the family Oonopidae (dwarf goblin spiders). It is the sole member of its genus, which was established by Simon in 1914 based on specimens originally described as Oonops inermis in 1882. The species is native to Europe and has been introduced to North America (Canada and USA).
Tapinopa bilineata
Tapinopa bilineata is a species of sheetweb spider in the family Linyphiidae, first described by Nathan Banks in 1893. It is a small arachnid found in North America, with records from the United States and Canada. Like other linyphiids, it constructs sheet webs to capture prey. The species is part of one of the most species-rich spider families, though specific ecological details for this particular species remain limited.
Tenuiphantes zebra
Zebra Thin Sheetweaver
Tenuiphantes zebra is a species of sheetweb spider in the family Linyphiidae, a group known for constructing flat, horizontal webs. First described by Emerton in 1882, this small spider is found in North America, with records from the United States and Canada. As a member of the dwarf spider family Linyphiidae, it contributes to terrestrial arthropod diversity in its range, though detailed ecological studies remain limited.
Tetragnatha
Stretch Spiders, Long-jawed Orb Weavers
Tetragnatha is a large genus of long-jawed orb-weaving spiders with hundreds of species distributed worldwide, though most occur in tropical and subtropical regions. These spiders are characterized by their elongated bodies, extremely long legs, and notably elongated chelicerae (jaws) with well-developed teeth. They construct horizontal orb webs, often near water, and many species can run across water surfaces. The genus exhibits remarkable variation in dispersal ability, with some species being excellent dispersers capable of colonizing islands, while others appear to have secondarily lost this capacity. Hawaiian Tetragnatha species have undergone adaptive radiation, with some lineages evolving cursorial (running) behavior and abandoning web-building entirely.
spiderorb-weaverlong-jawedaquaticstretch-spideradaptive-radiationHawaiicursorial-evolutionhorizontal-webwater-walkingcamouflagemultivoltinesocial-spiderTetragnathidaeAraneaeArachnidapredatorinsectivoreriparianwetlandmeadowtropicalsubtropicalcosmopolitandispersalisland-colonizationphylogeographychemical-species-recognitioncommunal-webbingkleptoparasitism-targetThallumetus pineus
Thallumetus pineus is a species of mesh-web weaver spider in the family Dictynidae, first described from specimens collected in the United States. It belongs to a genus of small spiders that construct irregular, tangled webs. The species epithet 'pineus' suggests an association with pine habitats. Very little is documented about its specific biology or ecology.
Theridiidae
tangle-web spiders, cobweb spiders, comb-footed spiders
Theridiidae is a large, globally distributed family of araneomorph spiders comprising over 2,600 species in more than 130 genera. Members are characterized by a comb of serrated bristles (setae) on the tarsus of the fourth leg, used to manipulate silk. The family exhibits remarkable diversity in web architecture, ranging from irregular tangle webs to specialized gumfoot webs and sheet-like structures. Theridiids are ecribellate, producing sticky capture silk rather than woolly silk, and are entelegyne with females possessing a genital plate. The family includes medically significant species such as widow spiders (Latrodectus), model organisms for social behavior research (Anelosimus), and specialized kleptoparasites (Argyrodinae).
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 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.
Thymoites pallidus
Thymoites pallidus is a species of comb-footed spider in the family Theridiidae, first described by Emerton in 1913. This species is known from Cuba, the United States, and the Caribbean region extending to Venezuela. Like other theridiid spiders, it possesses the characteristic comb-like serrated bristles (setae) on the tarsi of the hind legs used for manipulating silk. The species epithet 'pallidus' refers to its pale coloration.
Tibellus chamberlini
Chamberlin's Slender Crab Spider
Tibellus chamberlini is a species of running crab spider in the family Philodromidae, first described by Gertsch in 1933. It belongs to a genus of slender, elongate spiders adapted for ambush hunting on grasses and foliage. The species is distributed across the United States and Canada, though specific details of its biology remain poorly documented compared to better-known congeners.
Tinus
nursery web spider
Tinus is a genus of nursery web spiders in the family Pisauridae, established by F. O. Pickard-Cambridge in 1901. The genus includes small-bodied species that are notably smaller than most other pisaurid genera such as Dolomedes and Pisaurina. Tinus peregrinus is the best-documented species, known from the southwestern United States and northern Mexico. Members of this genus prefer vertical surfaces and are often found near water edges.
Titanoeca
Titanoeca is a genus of cribellate-web spiders in the family Titanoecidae, established by Thorell in 1870. The genus comprises 31 species as of January 2026, distributed primarily across Eurasia with notable exceptions: three species endemic to North America (T. americana, T. brunnea, T. nigrella), one holarctic species (T. nivalis), and one Ecuadorian endemic (T. guayaquilensis). Members construct cribellate webs and exhibit conditional foraging behavior.
Titiotus flavescens
Titiotus flavescens is a species of spider in the family Zoropsidae, commonly known as false wolf spiders or wandering spiders. The species was described by Chamberlin and Ivie in 1941. It is known from the United States, though specific details about its biology and ecology remain poorly documented in available literature.
Trebacosa marxi
Marx pirate spider
Trebacosa marxi is a wolf spider in the family Lycosidae, described by Stone in 1890. The species occurs in North America, with confirmed records from the United States and Canada. As a member of the genus Trebacosa, it belongs to a group of medium-sized wolf spiders. Limited detailed information is available regarding its specific biology and ecology.
Trochosa abdita
Trochosa abdita is a wolf spider (family Lycosidae) described by Gertsch in 1934. It belongs to the genus Trochosa, a group of ground-dwelling hunting spiders characterized by their distinctive eye arrangement. The species is known only from the United States, though specific details about its ecology and behavior remain poorly documented in the scientific literature.
Trogloneta
spurred orb-weavers
Trogloneta is a genus of minute spurred orb-weavers in the family Mysmenidae, described by Eugène Louis Simon in 1922. The genus currently comprises twelve described species distributed across Europe, East Asia, and the Americas. These spiders are among the smallest known spiders, with some species measuring less than 2 mm in body length. Several species exhibit cave-adapted characteristics and restricted distributions, with some Chinese species showing extreme population genetic divergence due to geographic isolation in karst cave systems.
Trogloneta paradoxa
Trogloneta paradoxa is a minute spider species in the family Mysmenidae, first described by Gertsch in 1960. Members of this family are among the smallest spiders known, with body lengths typically under 2 mm. The genus Trogloneta is characterized by a distinctive body shape featuring a disproportionately large, spherical posterior abdomen relative to the cephalothorax. The specific epithet "paradoxa" likely refers to this unusual morphology. The species is known from the United States.
Usofila pacifica
Usofila pacifica is a small true spider in the family Telemidae, described by Banks in 1894. It is found along the west coast of North America, from the United States into Canada. The species inhabits moist forest floor environments, where it constructs minute, delicate webs.
Walckenaeria palustris
Walckenaeria palustris is a species of dwarf spider in the family Linyphiidae, described by Millidge in 1983. The specific epithet 'palustris' (Latin for 'of the marsh') suggests association with wetland or marshy habitats. Like other members of the genus Walckenaeria, it is a small-bodied spider with characteristic genitalic structures used for species identification. The species has been recorded in Canada based on available distribution data.
Wubana pacifica
Wubana pacifica is a species of sheetweb spider in the family Linyphiidae. It was described by Nathan Banks in 1896. The species is known from the United States. As a member of Linyphiidae, it constructs flat, horizontal sheet webs rather than orb webs.
Wulfila tantillus
Wulfila tantillus is a species of ghost spider in the family Anyphaenidae, first described by Chickering in 1940. It belongs to a guild of active hunting spiders that do not construct webs for prey capture. The genus Wulfila is part of a family commonly referred to as ghost spiders due to their pale coloration and nocturnal habits. Observations of Wulfila spiders have been documented in association with urban tree canopies infested with scale insects, where they contribute to predator communities.
Xeropigo
Xeropigo is a genus of sac spiders in the family Corinnidae, first described by O. Pickard-Cambridge in 1882. The genus comprises 17 described species distributed across South America and the Caribbean, with the majority of species occurring in Brazil. Recent taxonomic revisions have significantly expanded the known diversity, with seven new species described from Brazil in 2016. The genus shows notable species richness in northeastern Brazilian states, particularly Piauí, Ceará, and Maranhão.
Xylesthia
Xylesthia is a genus of wall spiders in the family Oecobiidae, a group of small arachnids known for constructing flat, tangled webs on vertical surfaces such as walls, rocks, and tree trunks. These spiders are characterized by their compact bodies, relatively long legs, and distinctive spinneret arrangement. The genus is poorly documented in North American faunal surveys, with most species described from other regions. The 'n-sp' designation indicates an undescribed or unidentified species within the genus.
Xysticus apachecus
Xysticus apachecus is a species of crab spider in the family Thomisidae, first described by Gertsch in 1933. Like other members of the genus Xysticus, it is a ground-dwelling ambush predator characterized by its crab-like leg posture and sideways movement. The species is known from the United States, though specific details about its ecology and behavior remain limited in the published literature.
Xysticus montanensis
Montane Crab Spider
Xysticus montanensis is a species of crab spider in the family Thomisidae, first described by Keyserling in 1887. It is distributed across western and central North America, with records from Canadian provinces including Alberta, British Columbia, and Manitoba, as well as the United States. As a member of the genus Xysticus, it shares the typical crab spider morphology and ambush-hunting behavior, though species-specific details remain limited in the literature.
Xysticus possiblefunestus
Xysticus possiblefunestus is a species of crab spider in the family Thomisidae. The genus Xysticus comprises ground-dwelling crab spiders that are ambush predators, typically found in terrestrial habitats across the Northern Hemisphere. This species belongs to a diverse genus with over 360 described species worldwide. Like other Xysticus species, it likely exhibits the characteristic crab-like posture with enlarged front legs used for seizing prey. The specific epithet "possiblefunestus" suggests taxonomic uncertainty or similarity to Xysticus funestus, a European species.
Yorima angelica
Yorima angelica is a species of true spider in the family Cybaeidae, described by Roth in 1956. It is known from the United States. The genus Yorima belongs to a family of small to medium-sized spiders commonly found in leaf litter and other ground-level habitats. Information about this species is limited in the available literature.
Zoropsis spinimana
Mediterranean Spiny False Wolf Spider, Nosferatu-Spinne
Zoropsis spinimana is a medium-sized zoropsid spider native to the Mediterranean region that has expanded its range northward into Central and Northern Europe and been introduced to the United States and United Kingdom. The species is notable for its wolf spider-like appearance but with eyes more spread out along the cephalothorax, and for its strong association with human dwellings where it finds mild temperatures and abundant prey. It is an active nocturnal hunter that does not build webs. Sexual maturity occurs in autumn, with egg-laying in spring. Climate change and human-mediated transport have facilitated its range expansion.