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Araneomorphae
View on Wikipediafrom Wikipedia
| Araneomorph spiders Temporal range:
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|---|---|
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| Nephila inaurata (Nephilidae) | |
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| Pholcus phalangioides female with eggsac (Pholcidae) | |
Scientific classification 
| |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Subphylum: | Chelicerata |
| Class: | Arachnida |
| Order: | Araneae |
| Suborder: | Opisthothelae |
| Infraorder: | Araneomorphae |
| Subdivisions | |
| |
| Diversity | |
| 95 families | |
The Araneomorphae (also called the Labidognatha or "true spiders"[1]) are an infraorder of spiders. They are distinguishable by chelicerae (fangs) that point diagonally forward and cross in a pinching action, in contrast to those of Mygalomorphae (tarantulas and their close kin), which point straight down. Araneomorphs comprise the vast majority (about 93%[2]) of living spiders.
Distinguishing characteristics
[edit]Most spider species are Araneomorphae, which have fangs that face towards each other, increasing the orientations that they can employ during prey-capture. They have fewer book lungs (when present) – usually one pair – and the females typically live one year.
The Mygalomorphae have fangs that face towards the ground, and which are parallel to the long axis of the spider's body, thus they have only one orientation they can employ during prey capture. They have two pairs of book lungs, and the females often live many years.[3]
-
This Cheiracanthium punctorium shows the orientation of Araneomorphae fangs. -
This Atrax robustus shows the orientation of Mygalomorphae fangs.
Spiders included
[edit]Almost all of the familiar spiders are included in the Araneomorphae group, one major exception being the tarantulas. There are a few other Mygalomorphae species that live around homes or gardens, but they typically are relatively small and not easily noticed.
The Araneomorphae, to the contrary, include the weavers of spiral webs; the cobweb spiders that live in the corners of rooms, and between windows and screens; the crab spiders that lurk on the surfaces of flowers in gardens; the jumping spiders that are visible hunting on surfaces; the wolf spiders that carpet hunting sites in sunny spots; and the large huntsman spiders.
Systematics
[edit]In older schemes, the Araneomorphae were divided into two lineages, the Hypochilae (containing only the family Hypochilidae), and the Neocribellatae. The Neocribellatae were in turn divided into the Austrochiloidea, and the two series Haplogynae and Entelogynae, each containing several superfamilies. Molecular phylogenetic studies have shown that the haplogynes in particular are not a monophyletic group. A 2020 study suggested the relationships among the major groups were as shown in the following cladogram.[4]
| Araneomorphae | Haplogynae | |
The blue bar to the right shows the former Haplogynae in the sense of Coddington (2005).[5]
Table of families
[edit]| Genera | 1 | ≥2 | ≥10 | ≥100 |
| Species | 1–9 | ≥10 | ≥100 | ≥1000 |
Extinct families
[edit]Notes
[edit]- ^ Unless otherwise shown, currently accepted families and counts based on the World Spider Catalog version 25.5 as of 7 February 2025[update].[6] In the World Spider Catalog, "species" counts include subspecies. Assignment to sub- and infraorders based on Coddington (2005, p. 20) (when given there).
References
[edit]Citations
[edit]- ^ Coddington, J.A. (2005). "Phylogeny and Classification of Spiders" (PDF). In Ubick, D.; Paquin, P.; Cushing, P.E.; Roth, V. (eds.). Spiders of North America: an identification manual. American Arachnological Society. pp. 18–24. ISBN 978-0-9771439-0-0. Archived from the original (PDF) on 9 December 2008. Retrieved 12 October 2008.
- ^ Bern, Natural History Museum. "NMBE - World Spider Catalog". research.amnh.org. Retrieved 2023-06-07.
- ^ "ABOUT SPIDERS". www.publish.csiro.au. Retrieved 2022-01-07.
- ^ Magalhaes, Ivan L. F.; Azevedo, Guilherme H. F.; Michalik, Peter; Ramírez, Martín J. (February 2020). "The fossil record of spiders revisited: implications for calibrating trees and evidence for a major faunal turnover since the Mesozoic". Biological Reviews. 95 (1): 184–217. doi:10.1111/brv.12559. ISSN 1464-7931. PMID 31713947. S2CID 207937170.
- ^ Coddington, Jonathan A. (2005). "Phylogeny and classification of spiders" (PDF). In Ubick, D.; Paquin, P.; Cushing, P.E. & Roth, V. (eds.). Spiders of North America: an identification manual. American Arachnological Society. pp. 18–24. Retrieved 2015-09-24.
- ^ "Currently valid spider genera and species". World Spider Catalog. Natural History Museum Bern. Retrieved 2025-02-07. Currently valid spider genera and species
External links
[edit]
Media related to Araneomorphae at Wikimedia Commons
Data related to Araneomorphae at Wikispecies
| Arachnology |  | |
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| Taxonomy | ||
| Anatomy | ||
| Human interaction | ||
| Webs | ||
Araneomorphae
View on Grokipediafrom Grokipedia
Araneomorphae is the largest and most diverse suborder of spiders within the order Araneae, encompassing approximately 93% of all described spider species (around 49,800 species as of November 2025), distributed across about 110 families and over 4,000 genera worldwide.[1] These spiders, often referred to as "true spiders" or labidognath spiders, are distinguished by their chelicerae, which are oriented diagonally and move horizontally to oppose each other like pincers, enabling efficient prey capture through envenomation.[2] Unlike the more primitive suborders Mesothelae and Mygalomorphae, Araneomorphae typically possess six spinnerets for producing a variety of silk types used in web-building, draglines, and egg sacs, and they feature a combination of one pair of book lungs and tracheae for respiration.[3]
This suborder represents the evolutionary pinnacle of spider diversity, originating in the Triassic period around 240 million years ago and diverging from the lineage leading to Mygalomorphae, with the oldest fossils dating back approximately 230 million years to the Late Triassic (Carnian stage).[2] Araneomorphs exhibit remarkable adaptability, inhabiting nearly every terrestrial ecosystem from forests and deserts to urban environments, and they employ a wide array of hunting strategies, including orb-weaving, sheet-web construction, active hunting without webs, and even kleptoparasitism.[2] Notable families within Araneomorphae include Araneidae (orb-weavers, with over 3,100 species), Salticidae (jumping spiders, known for their acute vision and complex behaviors), and Theridiidae (cobweb spiders, including the medically significant genus Latrodectus).[3] Their silk production is particularly advanced, allowing for innovations like sticky orb webs that have made them highly effective predators of insects and other small arthropods.[2]
Ecologically, Araneomorphae play crucial roles as predators, contributing to pest control in agriculture and maintaining arthropod population balances in natural habitats, though some species pose risks to humans due to potent venoms.[2] With ongoing discoveries—as of November 2025, total described spider species at 53,546—the suborder continues to reveal new insights into arachnid evolution, silk biochemistry, and behavioral ecology through phylogenetic studies and genomic research.[1]
Conservation challenges affect certain Araneomorphae families, particularly those with narrow ranges; for instance, species formerly classified under Micropholcommatidae (now integrated into Anapidae) inhabit fragmented southern hemisphere forests with specialized litter habitats. Additionally, invasive species within families like Araneidae, such as Cyrtophora citricola, have expanded into new regions like the Caribbean and Cuba, potentially outcompeting native orb-weavers through rapid colonization and web dominance.
Fossils such as those resembling modern Nephila from approximately 100-million-year-old Burmese amber provide evidence of ancient web-building, with preserved silk glands and spinneret configurations indicating sophisticated orb-web production akin to extant araneids.[34] These specimens play a key role in elucidating the evolution of spider silk, revealing transitional forms in spinneret morphology and spigot arrangement that bridge primitive and advanced weaving techniques.[35]
Overview
Definition and classification
Araneomorphae is the largest suborder of spiders within the order Araneae, encompassing over 93% of all described spider species and approximately 50,000 species (93% of ~53,500 total described spiders) as of late 2025.[4] This suborder, often referred to as the "true spiders," is characterized by its immense diversity in form, behavior, and ecology, ranging from web-building orb weavers to active hunters.[5] In the taxonomic hierarchy, Araneomorphae constitutes one of three suborders under Araneae, alongside the basal Mesothelae and the sister suborder Mygalomorphae within the infraclass Opisthothelae; Araneomorphae itself is further divided into major clades such as Haplogynae and Entelegynae.[1] The suborder was first formally proposed by the French arachnologist Eugène Simon in his seminal work Histoire naturelle des araignées (1892), where he delineated it based on cheliceral morphology and other features distinguishing it from other spider groups. Subsequent classifications have refined this framework, with modern molecular phylogenetics providing robust support for its monophyly; for instance, a 2014 phylogenomic study by Bond et al. analyzed over 1,000 genes across 40 spider taxa and confirmed Araneomorphae's unity as a well-supported clade, rejecting earlier morphological uncertainties.[6] At the suborder level, key diagnostic traits of Araneomorphae include the anterior lateral spinnerets (ALS) featuring a field of piriform gland spigots used for producing attachment silk in webs and draglines, as well as the presence of a median apophysis—a sclerotized structure in the male palpal bulb involved in copulatory mechanics.[7] These traits, combined with the diagonal orientation of the chelicerae that allows for a pinching motion during prey capture, set Araneomorphae apart from its relatives.[8] Araneomorphae diverged from Mygalomorphae approximately 200–300 million years ago during the late Carboniferous to Early Permian.[9]Evolutionary history
The evolutionary history of Araneomorphae traces back to the late Paleozoic era, with the earliest potential stem-group representatives of more derived spiders appearing in the Carboniferous period around 300 million years ago (Mya). Early spider fossils from this period, such as those from Mazon Creek in Illinois, represent basal lineages like mesotheles rather than araneomorphs. Diversification of arachnids continued into the Permian, but the initial radiation of true araneomorphs is marked by Triassic fossils, such as Triassaraneus andersonorum from South African deposits around 225 Mya.[10] Molecular clock estimates indicate that Araneomorphae diverged from Mygalomorphae approximately 203–328 Mya during the Carboniferous–Permian transition, based on phylogenomic analyses incorporating mitochondrial genes such as 16S rRNA and COI alongside nuclear markers.[9][11] This divergence followed the earlier split from the basal Mesothelae, whose living representatives like Liphistiidae provide critical outgroup comparisons for reconstructing araneomorph phylogeny. Phylogenetic milestones include the Jurassic-era transition from cribellate to ecribellate silk systems, where ancestral cribellate capture threads (produced via a cribellum) gave way to more versatile ecribellate adhesives from aggregate glands, enabling innovations in web construction and prey capture.[9][11] Major radiations shaped the clade's trajectory, beginning with a Triassic explosion around 240 Mya, coinciding with the diversification of early seed plants and terrestrial arthropod communities that expanded foraging opportunities. In the Cretaceous (145–66 Mya), araneomorphs co-evolved with burgeoning insect faunas and the rise of angiosperms, fostering specialized predatory strategies like orb-weaving to exploit flying pollinators and floral resources, as seen in amber-preserved fossils from Lebanese and Burmese deposits. The Paleogene (66–23 Mya) witnessed a post-extinction burst following the Cretaceous–Paleogene boundary event, with spiders showing resilience—no family-level declines—and subsequent proliferation into vacated niches, driving the dominance of modern araneomorph diversity.[9][12][13]Morphology
Distinguishing characteristics
Araneomorphae exhibit a body plan consisting of a prosoma and opisthosoma connected by a narrow pedicel, with the ventral surface of the opisthosoma featuring an epigastric furrow that delineates the anterior epigastric region—housing the book lungs and genital structures—from the posterior portion of the abdomen.[14] This furrow marks a flexible boundary that facilitates abdominal movement and is more pronounced in derived lineages. The chelicerae are two-segmented appendages with a diaxial (labidognath) orientation, directed forward and capable of crossing in a scissor-like motion to pinch and envenomate prey, differing from the subvertical, parallel alignment seen in Mygalomorphae.[15] The silk-producing apparatus in Araneomorphae typically comprises six spinnerets organized into three pairs: anterior median spinnerets (AMS), anterior lateral spinnerets (ALS), and posterior lateral spinnerets (PLS), although the posterior median spinnerets (PMS) are often reduced, fused, or absent in certain groups. The ALS are the most prominent, equipped with flagelliform spigots that produce dragline silk for safety lines and bridging, as well as piriform spigots that secrete attachment silk for securing threads to surfaces.[16] This configuration enables diverse silk applications central to araneomorph ecology. Araneomorphae generally follow a leg formula of 4-1-3-2, where the fourth pair of legs is the longest, followed by the first, second, and third pairs, aiding in locomotion and web manipulation. The legs are adorned with trichobothria—fine sensory setae that detect airborne vibrations and air currents—arranged in specific patterns that enhance prey detection and environmental awareness.[14] These morphological traits, including the cheliceral orientation and spinneret specialization, represent key synapomorphies supporting the monophyly of Araneomorphae within spider phylogeny.| Group | Cheliceral Type | Spinneret Configuration |
|---|---|---|
| Mesothelae | Chelate, subvertical | Four pairs, mid-ventral on segmented abdomen |
| Mygalomorphae | Paraxial, subvertical | Four spinnerets, terminal; ALS reduced or absent |
| Araneomorphae | Diaxial (labidognath), forward-pointing | Six spinnerets, terminal; ALS prominent with flagelliform and piriform spigots |
Sensory and reproductive structures
Araneomorphae spiders typically possess eight eyes arranged in two rows, consisting of four pairs: the anterior median eyes (AME), anterior lateral eyes (ALE), posterior median eyes (PME), and posterior lateral eyes (PLE). The AME, often the largest and serving as principal eyes homologous to median eyes in other arthropods, provide high-resolution vision, while the secondary eyes (ALE, PME, PLE) contribute to a wide field of view.[17] Many araneomorph families, such as Lycosidae (wolf spiders), feature a tapetum lucidum—a guanine-based, grate-shaped reflective layer—in their secondary eyes, which enhances low-light vision by reflecting photons back through the retina to increase sensitivity in dim conditions. This adaptation supports crepuscular and nocturnal foraging, with peak reflectance in the green spectrum, though it may compromise visual acuity compared to diurnal species.[18] Tactile sensing in Araneomorphae relies on slit sensilla concentrated on the proximal leg segments and tarsi, forming mechanoreceptors that detect substrate strain and vibrations through cuticular deformation. These organs, often grouped into lyriform arrays near joints, enable precise monitoring of mechanical stresses during locomotion and prey capture.[19] Chemosensory capabilities are prominent on the pedipalps, particularly in males, where a multisensillar organ at the base of the palpal embolus serves as a chemo- and mechanoreceptor for assessing female pheromones and cuticular cues during mate location and courtship. This internalized structure, resembling tarsal chemoreceptors, provides sensory feedback to facilitate precise sperm transfer.[20] In male Araneomorphae, the palpal bulb functions as the primary copulatory organ, featuring a long, thin, curved embolus for sperm delivery and a prominent, ridged conductor that guides the embolus during insertion into the female's epigyne. These sclerotized components exhibit species-specific morphologies, innervated by neurite bundles from the bulb nerve to ensure accurate mating mechanics.[21] Females possess an epigyne, a sclerotized ventral plate overlying the genital opening, which directs sperm via paired copulatory ducts to spermathecae—internal, species-specific sacs that store sperm in an encapsulated state until fertilization during egg-laying. The epigyne's structure, including potential protrusions like a scape in some taxa, prevents improper insemination and supports post-copulatory selection.[22] Parthenogenesis occurs in certain Araneomorphae, such as the oonopid spider Triaeris stenaspis, where females reproduce thelytokously, producing viable female offspring from unfertilized eggs without bacterial endosymbionts like Wolbachia. Isolated females lay fertile egg sacs averaging 27 eggs, with all progeny developing into females across three juvenile instars.[23] Variations in sensory structures include eye reduction in cave-dwelling Araneomorphae, such as Leptonetela sublunata with highly reduced eyes and Leptonetela tetracantha that is completely eyeless, adaptations to perpetual darkness that conserve energy while retaining underlying circadian mechanisms responsive to blue light. Courtship involves specialized structures like the retrolateral tibial apophysis on male pedipalps, which stabilizes mating positions and limits female aggression through sexual selection pressures.[24][25]Systematics
Phylogenetic relationships
Araneomorphae, the largest clade of spiders, exhibits a phylogenetic structure characterized by a basal grade of paraphyletic Haplogynae—lacking an epigyne in females—and the monophyletic Entelegynae, which possess a complex epigyne for sperm storage and transport. This division is supported by molecular analyses using 18S rRNA gene sequences and multi-gene datasets, which recover high bootstrap support (typically >90%) for the Entelegynae, alongside morphological synapomorphies such as the sclerotized epigynal structures. Within Araneomorphae, the monophyly of the clade is robustly confirmed by phylogenomic datasets, with ultrafast bootstrap values exceeding 95% in analyses encompassing ribosomal, protein-coding loci, and ultraconserved elements (UCEs).[26] Key nodes in the Araneomorphae tree highlight early divergences and major radiations. The UDOH grade (Uloboridae, Deinopidae, Oecobiidae, Hersiliidae), comprising early-diverging lineages within Entelegynae, is distinguished by cribellate silk production in some members via a cribellum, a plesiomorphic trait lost in most advanced araneomorphs; molecular support places these families at the base of Entelegynae with moderate to high bootstrap values (70-100%) in combined phylogenomic analyses. The traditional Deinopoidea (Deinopidae + Uloboridae) lacks monophyly in recent studies.[26] The RTA-clade (Retrolateral Tibial Apophysis clade), encompassing the diverse Dionycha group with two-clawed tarsi, emerges as a well-supported monophyletic assemblage (ultrafast bootstrap >95%) within Entelegynae, characterized by a retrolateral apophysis on the male tibial palp, comprising over half of all spider species. Synspermiata, a derived group featuring synchronized sperm transfer via synspermia, occupies a basal position within Haplogynae relative to Entelegynae, with strong nodal support (ultrafast bootstrap 90-100%) from phylogenomic data integrating UCEs, transcriptomes, and mitochondrial markers.[26] Recent phylogenetic revisions have clarified longstanding uncertainties. The 2017 target-gene study by Wheeler et al., analyzing 932 species with six genetic markers, provided an extensive sampling that confirmed Araneomorphae monophyly and influenced calibrations for araneomorph trees.[27] Conflicts regarding the relationships among orb-weaving groups and the RTA-clade have been addressed by 2023 phylogenomic analyses (Kulkarni et al.), which refute the monophyly of Orbiculariae and position orb-weaving families (e.g., Araneoidea) as derived within Entelegynae sister to the RTA-clade plus Sparassidae, with ultrafast bootstrap support >90%.[26] A cladogram of Araneomorphae based on recent phylogenomic studies (Kulkarni et al. 2023) depicts the following topology: Araneomorphae (100% ultrafast bootstrap) includes basal Haplogynae [Austrochiloidea (100%) + Synspermiata (100%) + other haplogynes] + Entelegynae (100%): UDOH grade (~80%) + [Sparassidae + RTA-clade (98%, including Dionycha)] + derived clades (e.g., Araneoidea >95%). This structure underscores the clade's evolutionary progression from simpler genital systems to specialized silk and web architectures, with nodal supports reflecting concatenated phylogenomic alignments.[26]Major infraorders and clades
Araneomorphae is divided into several major infraorders and clades based on morphological and molecular data, with recent phylogenomic analyses using ultraconserved elements (UCEs) and morphological characters resolving long-standing conflicts in their relationships. The basal group is Haplogynae, a paraphyletic assemblage characterized by simple female genitalia with a single genital opening and fused copulatory/fertilization ducts, lacking the hardened structures typical of more derived groups. This grade includes approximately 7-10% of all spider species, with around 20 families such as Dysderidae, Oonopidae, and Pholcidae, many of which are ground-dwelling hunters with reduced eye numbers or specialized habits like sheet-web building.[26][1] The UDOH grade (Uloboridae, Deinopidae, Oecobiidae, Hersiliidae) represents early-diverging lineages of cribellate orb-weavers within Entelegynae, distinguished by the presence of a cribellum (a sieve-like silk-producing organ) and calamistrum (a comb on metatarsus IV for handling cribellate silk) in some members, as well as the absence of venom glands in Uloboridae. Examples include Deinopis (ogre-faced spiders) that construct backward-striking "ladder webs" for prey capture, and Uloborus, which spin orb webs with hackled silk bands. Recent phylogenies position these families at the base of Entelegynae, with Deinopidae sister to Hersiliidae + Oecobiidae, highlighting the non-monophyly of traditional Deinopoidea and the primitive silk production system in this grade.[26] The RTA-clade (Retrolateral Tibial Apophysis clade) is a diverse monophyletic group within Entelegynae defined by the presence of a retrolateral apophysis on the male pedipalp tibia, often associated with cursorial hunting lifestyles and reduced web use. It encompasses superfamilies like Lycosoidea and Thomisoidea, including families such as Lycosidae (wolf spiders) and Salticidae (jumping spiders), which together account for a significant portion of araneomorph diversity through active foraging behaviors. Phylogenetic analyses place the RTA-clade sister to Sparassidae and derived entelegyne clades.[26] Entelegynae, the dominant group comprising about 90-93% of araneomorph species, is characterized by complex female genitalia featuring separate copulatory and fertilization ducts, often with an epigynum (a sclerotized genital plate), and venom glands extending into the prosoma. This clade includes orb-weaving families like Araneidae and ecologically versatile groups such as Theridiidae (cobweb spiders), with many species constructing sticky orb webs or irregular three-dimensional capture webs. Entelegynae's monophyly is robustly supported (100% ultrafast bootstrap), encompassing the majority of web-building and hunting strategies in spiders, though orb-weaving evolved multiple times.[26] Recent phylogenomic studies have identified emerging basal clades within Araneomorphae, refining the structure of Haplogynae. Austrochiloidea is a monophyletic group of primitive spiders with two pairs of book lungs in some taxa and cribellate silk production, including Austrochilidae (e.g., Austrochilus from South America) and Gradungulidae (e.g., Gradungula from Australia). Synspermiata, another key clade, consists of ecribellate haplogynes with unique synsperm formation (fusion of spermatids into compound sperm packets) and complex internal genitalia, encompassing families like Leptonetidae, Oonopidae, and Pholcidae (daddy longlegs spiders). These clades are positioned near the base of Araneomorphae, with Austrochiloidea sister to Synspermiata + other haplogynes in UCE-based analyses (100% support).[26]Diversity
Extant families
Araneomorphae encompasses 95 recognized extant families, as documented in the World Spider Catalog, representing the vast majority of spider diversity with over 50,000 species.[1] These families are primarily grouped within major infraorders such as Synspermiata, Austrochiloidea, Palpimanoidea, and Entelegynae, reflecting their phylogenetic placement in the RTA clade.[1] The suborder's families vary widely in size, from highly speciose groups with thousands of species to small, endemic lineages restricted to specific regions. Among the largest families, Salticidae stands out with approximately 6,930 species, known as jumping spiders for their agile hunting behavior and acute vision; these are distributed worldwide, particularly in tropical and temperate zones.[4] Theridiidae follows with about 2,622 species, commonly called cobweb spiders due to their irregular, tangled webs, and they occur globally with a strong presence in forests and human habitats.[4] Araneidae, the orb-weavers, comprises around 3,160 species that construct characteristic wheel-shaped webs for prey capture, exhibiting a cosmopolitan distribution but peaking in diversity in the tropics.[4] Other notable large families include Linyphiidae (~4,963 species, sheetweb weavers) and Lycosidae (~2,509 species, wolf spiders), both contributing significantly to the suborder's ecological roles as predators.[4] The following table summarizes selected extant families, highlighting diversity metrics, geographic ranges, and distinguishing traits; it includes major groups and examples of endemics for representation.| Family | Species Count | Distribution | Key Traits |
|---|---|---|---|
| Salticidae | 6,930 | Worldwide, esp. tropics | Active hunters; large forward-facing eyes; no webs, rely on jumping.[4] |
| Araneidae | 3,160 | Cosmopolitan, diverse habitats | Orb-shaped webs; often colorful; diurnal web-builders.[4] |
| Theridiidae | 2,622 | Worldwide, forests to urban | Irregular cobwebs; sticky silk globules on feet for prey handling.[4] |
| Linyphiidae | 4,963 | Holarctic, temperate | Sheet-like webs; tiny size; prolific in leaf litter.[4] |
| Lycosidae | 2,509 | Worldwide, ground-dwellers | Wolf-like pursuit hunting; burrow or free-roaming; no webs.[4] |
| Austrochilidae | 9 | Southern Hemisphere (Chile, Argentina, Tasmania) | Sheet webs near water; primitive retrolateral tibial apophysis (RTA); endemic to temperate rainforests.[28][29] |
| Anapidae (incl. former Micropholcommatidae) | 233 | Gondwanan regions, southern temperate forests | Miniature size (<2 mm); reduced book lungs; tiny irregular webs in leaf litter.[30] |
Extinct families
Approximately 20 extinct families of Araneomorphae have been described from the fossil record, with the majority known from Mesozoic amber deposits including those from Baltic, Dominican, Burmese, and Lebanese sources.[10] These fossils, often preserved with fine details such as spinneret impressions, highlight the early diversification of araneomorph lineages during the Triassic to Cretaceous periods. Prominent examples include the Palaeoaraneidae, from the Triassic Molteno Formation of South Africa and the Cow Branch Formation of Virginia, USA, which display primitive chelicerae and other features suggestive of early araneomorph evolution, although they lack some definitive synapomorphies of the clade. The Juraraneidae, documented from Jurassic sediments in Kazakhstan, represent early analogs to orb-weaving spiders, with body and leg structures indicating potential sheet-web construction.[31] Similarly, the Eoplectreuridae from Cretaceous amber deposits exhibit morphologies akin to modern Clubionidae, including compact bodies and leg spination patterns adapted for ground-dwelling.[32] Other notable extinct families encompass the Lagonomegopidae from Cretaceous ambers of Taimyr Peninsula, Myanmar, and New Jersey, characterized by enormously enlarged posterior median eyes that imply diurnal or visually oriented behaviors.[33]| Family | Geological Period | Location | Notable Features |
|---|---|---|---|
| Palaeoaraneidae | Triassic | South Africa, USA | Primitive chelicerae; early araneomorph traits |
| Juraraneidae | Jurassic | Kazakhstan | Leg and body structures suggesting sheet-webs |
| Eoplectreuridae | Cretaceous | Myanmar amber | Compact habitus similar to ground hunters |
| Lagonomegopidae | Cretaceous | Myanmar, Taimyr, New Jersey | Enlarged posterior median eyes; robust build |