Ortholasma rugosum is a species of harvestman (Opiliones) in the family Nemastomatidae, first described by Banks in 1894. It is found in North America and is one of approximately 163 observed records according to iNaturalist data. The genus Ortholasma belongs to the subfamily Ortholasmatinae, a group of small-bodied harvestmen characterized by distinctive morphological features.
Orthonops lapanus is a small spider species in the family Caponiidae, described by Gertsch and Mulaik in 1940. It belongs to a genus of spiders characterized by reduced eye numbers and elongated bodies. The species is known from limited records in the United States.
Oskoron spinosus is a harvestman (order Opiliones) and the type species of the genus Oskoron, established to accommodate this species and two close relatives distinct from the genus Taracus. Originally described as Taracus spinosus by Banks in 1894, it was later treated as Taracus malkini before being synonymized and transferred to the new genus Oskoron. It belongs to the family Taracidae within the superfamily Ischyropsalidoidea.
Pandionacarus fuscus is a species of mite in the family Avenzoariidae, order Sarcoptiformes. The genus name indicates an association with the osprey genus Pandion, suggesting this mite may be an ectoparasite or commensal of ospreys. Very little published information exists on the biology or ecology of this species. The species was described by Nitzsch in 1818, indicating it has been recognized in scientific literature for over two centuries.
microwhip scorpion, palpigrade, micro whipscorpion
Palpigradi is an order of minute arachnids, commonly called microwhip scorpions or palpigrades. They are the sister group to Solifugae (camel spiders), measuring 1–3 mm in length. These pale, thin-bodied arachnids inhabit wet tropical and subtropical soils worldwide, living interstitially in moist microhabitats under stones and in caves. They possess a distinctive multi-segmented flagellum that may comprise half the body length. The order contains two families, Prokoeneniidae and Eukoeneniidae, distinguished by the presence or absence of ventral respiratory sacs.
Paramaevia is a genus of jumping spiders in the family Salticidae. First described as a subgenus of Maevia in 1955, it was elevated to genus status in 1958, reduced to a junior synonym of Maevia in 1977, and reinstated as a valid genus by Jerzy Prószyński in 2017. The genus contains at least three described species. When included in Maevia, it was placed in the tribe Dendryphantini within the Salticoida clade of the subfamily Salticinae.
Paraphidippus fartilis is a species of jumping spider in the family Salticidae. It is native to the southwestern United States, Mexico, and Central America. The species was originally described by Peckham & Peckham in 1888 under the name Philaeus fartilis. Like other jumping spiders, it possesses excellent vision and active hunting behavior.
mites and ticks
Parasitiformes is a superorder of arachnids constituting one of two major mite lineages, alongside Acariformes. The group includes ticks (Ixodida), the highly diverse predatory and parasitic Mesostigmata, the small scavenging Holothyrida, and the large segmented Opilioacarida. Over 12,000 species have been described, with estimates of 100,000–200,000 total species. Recent phylogenomic analyses indicate Parasitiformes is more closely related to other chelicerates (spiders, scorpions, horseshoe crabs) than to Acariformes, challenging the traditional unification of all 'mites' as a single natural group.
Stripe-tailed scorpion
A medium-sized scorpion in the family Vaejovidae, found in the southwestern United States and northern Mexico. It was originally described as Vaejovis puritanus in 1958 and later transferred to the genus Paravaejovis. The species is one of several stripe-tailed scorpions in the region and is frequently encountered in desert and semi-arid habitats.
stripe-tailed scorpion, devil scorpion
Paravaejovis spinigerus, commonly known as the stripe-tailed scorpion or devil scorpion, is a medium-sized scorpion native to the Sonoran Desert region. Adults reach 60–70 mm in length and weigh approximately 9.5 g. The species was transferred from the genus Hoffmannius to Paravaejovis in 2013. Its venom is not medically significant to humans.
Dune Devil Scorpion
Paravaejovis waeringi, commonly known as the dune devil scorpion, is a scorpion species in the family Vaejovidae. It is native to the Colorado Desert of North America. The species was originally described as Vaejovis waeringi by Williams in 1970 before being transferred to the genus Paravaejovis. It is one of the scorpion species adapted to arid desert environments.
Pardosa californica is a species of thin-legged wolf spider in the family Lycosidae, first described by Keyserling in 1887. It belongs to the genus Pardosa, which comprises small to medium-sized wolf spiders characterized by long spines on their legs that are nearly perpendicular to the leg axis. The species is found in the United States and Mexico. Like other members of its genus, it is likely associated with moist habitats near water sources, though specific ecological details for this species remain limited.
Pardosa dorsuncata is a species of thin-legged wolf spider in the family Lycosidae. It was described by Lowrie and Dondale in 1981. The species is found in the United States and Canada, with records from Alberta and British Columbia in Canada. As a member of the genus Pardosa, it shares characteristics typical of this widespread group of small to medium-sized wolf spiders.
Groenland Wolf Spider, Greenland Wolf Spider
Pardosa groenlandica is a species of wolf spider in the family Lycosidae, commonly known as the Groenland Wolf Spider or Greenland Wolf Spider. It is one of approximately 65 Pardosa species recognized in the United States and 75 species north of Mexico. The species has a notably broad distribution spanning arctic and subarctic regions across multiple continents.
Little Banded Wolf Spider
Pardosa modica is a species of wolf spider in the family Lycosidae, commonly known as the Little Banded Wolf Spider. It is one of approximately 65 Pardosa species recognized in the United States and 75 species north of Mexico. As a member of the 'thin-legged wolf spiders,' it is characterized by distinctive leg spines and is typically small to medium in size. The species is distributed across the United States and Canada, including records from Alberta and Manitoba.
Paruroctonus is a genus of small to medium-sized scorpions in the family Vaejovidae, containing approximately 30 described species distributed primarily in arid regions of western North America. The genus includes notable alkali sink specialists such as P. soda and P. conclusus, which inhabit dry lake beds (playas) in California. Several species have been studied for their chemical communication systems and thermal ecology.
Paruroctonus luteolus is a species of scorpion in the family Vaejovidae, originally described as Vaejovis luteolus by Gertsch & Soleglad in 1966. It belongs to the genus Paruroctonus, which includes several alkali-sink specialist species found in arid regions of western North America. The species is known from Middle America and North America, though specific details about its ecology and behavior remain limited in available literature.
Peckhamia is a genus of ant-mimicking jumping spiders (family Salticidae) first described by Eugène Louis Simon in 1900, named in honor of arachnologists George and Elizabeth Peckham. Species in this genus exhibit striking myrmecomorphy—mimicking ants in body shape, movement patterns, and behavior. The genus is distinguished from related ant-mimicking genera such as Synageles by a more convex carapace in the cephalic area that slopes sharply downward behind the third row of eyes. Peckhamia species characteristically hold their second pair of legs aloft to simulate ant antennae, enhancing their deceptive appearance.
A species of jumping spider in the family Salticidae, characterized by its yellowish head (as indicated by the species epithet flaviceps, meaning 'yellow-headed'). It is found in the northeastern United States and southeastern Canada. The species was described by Kaston in 1973. As a member of the genus Pelegrina, it shares the typical salticid traits of excellent vision and active hunting behavior.
Pelegrina pervaga is a species of jumping spider (family Salticidae) described by G.W. Peckham and E.G. Peckham in 1909. It occurs in the United States. Like other salticids, it possesses excellent vision and active hunting behavior. The genus Pelegrina contains multiple species of small to medium-sized jumping spiders distributed primarily in North America.
harvestmen
Phalangioidea is a superfamily of harvestmen (order Opiliones) within the suborder Eupnoi, comprising five families and over 1,500 species. Members are characterized by relatively long legs, fused body regions (cephalothorax and abdomen not separated by a pedicel), and the absence of venom glands and silk production. The superfamily includes the common long-legged harvestmen frequently encountered in temperate regions. Phalangioidea is distinct from the similarly named Phalangodoidea, a superfamily within the suborder Laniatores.
mesh web weaver
Phantyna bicornis is a species of mesh web weaver spider in the family Dictynidae. It was described by Emerton in 1915. The species is known from North America, with records from the United States and Canada.
California Red Jumping Spider
Phidippus adumbratus is a jumping spider in the family Salticidae, commonly known as the California Red Jumping Spider. It belongs to the insignarius species group within the genus Phidippus. The species was first described by Gertsch in 1934 from a type specimen collected in Los Angeles. Its specific epithet derives from Latin adumbratus, meaning 'secret' or 'in the dark,' possibly alluding to the missing abdomen of the holotype specimen.
Phidippus boei is a species of jumping spider in the family Salticidae, described by G.B. Edwards in 2004. Like other members of the genus Phidippus, it possesses the characteristic large anterior median eyes that provide excellent vision for hunting. The species occurs in the southwestern United States and Mexico. Information on its specific biology remains limited compared to better-studied congeners.
Hairy Tufted Jumping Spider
Phidippus comatus is a species of jumping spider in the family Salticidae, distributed across North America including Canada, the United States, and Mexico. The species belongs to the genus Phidippus, which includes some of the largest jumping spiders in North America. Like other members of this genus, it possesses the characteristic enlarged anterior median eyes that provide excellent vision for hunting. The specific epithet 'comatus' refers to the hairy or tufted appearance.
Phidippus lynceus is a species of jumping spider in the family Salticidae, described by G.B. Edwards in 2004 as part of his revision of the genus Phidippus. As a member of this genus, it belongs to a group of relatively large, visually oriented hunting spiders known for their acute eyesight and complex behaviors. The species epithet "lynceus" derives from Greek mythology, referring to Lynceus, a figure noted for his exceptional vision. Specific details regarding its morphology, habitat preferences, and natural history remain poorly documented in the accessible literature, reflecting the challenges of studying this diverse genus of spiders.
Phidippus morpheus is a species of jumping spider in the family Salticidae, described by G.B. Edwards in 2004. It belongs to a genus of relatively large, colorful jumping spiders found primarily in North America. Like other Phidippus species, it possesses the characteristic enlarged anterior median eyes that provide acute vision for hunting. The species name references Morpheus, the Greek god of dreams, though the specific reason for this epithet is not documented in available sources.
Phoenix Jumping Spider
Phidippus phoenix is a species of jumping spider described by G.B. Edwards in 2004. It belongs to the genus Phidippus, which includes some of the largest and most conspicuous jumping spiders in North America. The species occurs in the southwestern United States and Mexico, where it inhabits arid and semi-arid environments. Like other Phidippus species, it possesses excellent vision and active hunting behavior characteristic of the family Salticidae.
Tux jumping spider
Phidippus tux is a species of jumping spider in the family Salticidae, first described by Pinter in 1970. It is found in the southwestern United States and Mexico. As a member of the genus Phidippus, it belongs to a group of relatively large, colorful jumping spiders known for their excellent vision and active hunting behavior. Specific details about its appearance, behavior, and ecology remain poorly documented in the available literature.
Phidippus vexans is a species of jumping spider in the family Salticidae, described by G.B. Edwards in 2004. As a member of the genus Phidippus, it shares the characteristic large anterior median eyes and active hunting behavior typical of salticid spiders. The species is known from the United States, though detailed ecological and behavioral information remains limited in published sources.
Philodromus josemitensis is a species of running crab spider in the family Philodromidae. It occurs in the United States and Canada. As a member of the genus Philodromus, it shares the characteristic laterigrade leg orientation that allows sideways movement. The species was described by Gertsch in 1934.
running crab spider
Philodromus laticeps is a species of running crab spider in the family Philodromidae. It is native to the United States. As a member of the genus Philodromus, it exhibits the characteristic laterigrade leg orientation typical of running crab spiders, allowing sideways movement.
Philodromus lutulentus is a running crab spider in the family Philodromidae, described by Gertsch in 1934. As a member of the genus Philodromus, it shares the characteristic laterigrade leg orientation that distinguishes this group from other crab spiders. The species epithet 'lutulentus' refers to something muddy or turbid, possibly alluding to coloration or habitat associations. Like other philodromids, it is an active hunter that does not build webs to capture prey.
running crab spider
Philodromus placidus is a species of running crab spider in the family Philodromidae. It is commonly found across North America, with distribution records from Canada (Alberta, Manitoba, Saskatchewan) and the United States. As a member of the Philodromidae, it is an active hunter that does not build webs to capture prey.
running crab spider
Philodromus rodecki is a species of running crab spider in the family Philodromidae. It occurs in the United States and Canada. As a member of the genus Philodromus, it shares the family's characteristic laterigrade leg orientation, allowing sideways movement. The species was described by Gertsch and Jellison in 1939.
Philodromus rufus quartus is a subspecies of running crab spider described by Dondale & Redner in 1968. It belongs to the family Philodromidae, a group of active hunters that do not build webs to capture prey. The subspecies is distributed across a broad Palearctic range including France, Korea, and parts of Russia and Central Asia. As a member of the Philodromus rufus species complex, it exhibits the characteristic laterigrade leg posture and flattened body form typical of bark-dwelling crab spiders.
Philodromus spectabilis is a running crab spider in the family Philodromidae, distributed across the United States and Canada. As a member of this family, it exhibits the characteristic laterigrade leg posture that enables sideways movement. The species has been documented in multiple Canadian provinces including Alberta, Manitoba, and Saskatchewan, as well as throughout the United States. It is one of many Philodromus species that occasionally enters human dwellings and has been observed in indoor environments such as bathrooms.
longlegged crab spider
Philodromus vulgaris is a running crab spider in the family Philodromidae, commonly known as the longlegged crab spider. It is a small to medium-sized spider found across North America, including the United States and Canada. The species belongs to a genus known for its flattened body form and laterigrade leg orientation, adaptations that facilitate sideways movement and hunting on flat surfaces. It is one of numerous Philodromus species documented in the region, though specific biological details remain limited in published literature.
Philoponella arizonica is a species of crevice weaver spider in the family Uloboridae, first described by Gertsch in 1936. The species occurs in the southwestern United States and Mexico. Like other members of the genus Philoponella, it constructs characteristic sprawling, lacy cribellate webs that issue from retreats in crevices and sheltered locations. Females are notably long-lived and continue to molt after reaching sexual maturity, a trait shared only with mygalomorph spiders among arachnids.
Phlegra hentzi is a species of jumping spider in the family Salticidae. It occurs in the United States and Canada. As a member of the genus Phlegra, it belongs to a group of small to medium-sized jumping spiders known for their active hunting behavior and excellent vision. The species was described by George Marx in 1890.
Phrurolithus pipensis is a species of true spider in the family Phrurolithidae, first described by Muma in 1945. It is known from the United States. Members of this family are generally small, ground-dwelling spiders.
Phrurotimpus alarius is a species of true spider in the family Phrurolithidae, originally described by Hentz in 1847. It occurs in the United States and Canada. The species includes two recognized subspecies: P. a. alarius and P. a. tejanus. It belongs to a genus of small, ground-dwelling spiders often associated with leaf litter and similar habitats.
tailless whipscorpion
A medium-sized tailless whipscorpion (18–22 mm total length) found across much of Mexico. Distinguished by chestnut coloration with reddish tones on the carapace and pedipalps, four anterior spines on the pedipalp trochanter, and specific female gonopod morphology. The species shows considerable morphological variation across its range, suggesting it may represent a species complex.
Phyllocoptes didelphis is a minute eriophyid mite in the family Eriophyidae. This species belongs to a genus containing many gall-forming and vagrant plant-feeding mites. The specific epithet 'didelphis' refers to the Virginia opossum (Didelphis virginiana), though the reason for this association is not documented in available sources. Eriophyid mites are among the smallest arthropods and are exclusively associated with plants.
Piabuna is a genus of small, ground-dwelling spiders in the family Phrurolithidae, endemic to North America. First described in 1933, it has undergone multiple family reassignments, reflecting ongoing revisions in spider systematics. The genus contains six described species distributed primarily in the southwestern United States and Mexico. These spiders are rarely encountered and poorly known in terms of natural history.
large hammockweb spider
Pimoa altioculata is a large hammockweb spider in the family Pimoidae, found in the western United States and Canada. It was formerly classified in the family Linyphiidae but was separated due to distinct morphological differences, particularly its substantially larger body size. The species constructs fine, horizontal, net-like webs and is primarily associated with coniferous forest habitats.
dwarf spider
Pocadicnemis pumila is a species of dwarf spider in the family Linyphiidae, first described by John Blackwall in 1841. It has a notably wide distribution spanning multiple continents, including North America, Europe, Turkey, the Caucasus, Russia (from European Russia to the Far East), Iran, and Japan. The species belongs to a family commonly known as sheet-web weavers or money spiders, though specific behavioral details for this species remain poorly documented.
Poeciloneta lyrica is a species of sheetweb spider in the family Linyphiidae, first described by Zorsch in 1937. It belongs to a diverse family of small spiders known for constructing flat, sheet-like webs. The species has been recorded in North America, with confirmed observations in Alberta, Canada. Available information on this species remains limited.
Prodidomus is a genus of long-spinneret ground spiders in the family Prodidomidae, first described by Nicholas Marcellus Hentz in 1847. The genus comprises 54 species as of September 2025. Members are small spiders, with males measuring 1.9–4.3 mm and females 1.8–5.0 mm in total length. They are distinguished by their elongated anterior lateral spinnerets, which measure 10–20% of abdominal length, and their distinctive eye arrangement with greatly enlarged, canoe-shaped posterior lateral eyes.
microscorpions, microwhip scorpions
Prokoeneniidae is a family of microscorpions (order Palpigradi) established by Condé in 1996. The family contains at least two genera—*Prokoenenia* and *Triadokoenenia*—with approximately seven described species. These minute arachnids are among the least studied of all arachnid orders, reflecting their cryptic lifestyle and small size.