Spider taxonomy

Spider taxonomy is that part of taxonomy that is concerned with the science of naming, defining and classifying all spiders, members of the Araneae order of the arthropod class Arachnida with more than 48,500 described species.[1] However, there are likely many species that have escaped the human eye to this day, and many specimens stored in collections waiting to be described and classified. It is estimated that only one third to one half of the total number of existing species have been described.[2]

Paintings of Araneus angulatus from Svenska Spindlar of 1757, the first major work on spider taxonomy

Arachnologists currently divide spiders into two suborders with about 129 families.

Due to constant research, with new species being discovered every month and others being recognized as synonyms, the number of species in the families is bound to change and only reflects the present state of knowledge. Nevertheless, the species numbers given here are useful as a guideline – see the table of families at the end of the article.

History

Spider taxonomy can be traced to the work of Swedish naturalist Carl Alexander Clerck, who in 1757 published the first binomial scientific names of some 67 spiders species in his Svenska Spindlar ("Swedish Spiders"), one year before Linnaeus named over 30 spiders in his Systema Naturae. In the ensuing 250 years, thousands more species have been described by researchers around the world, yet only a dozen taxonomists are responsible for more than a third of all species described. The most prolific authors include Eugène Simon of France, Norman Platnick and Herbert Walter Levi of the United States, Embrik Strand of Norway, and Tamerlan Thorell of Sweden, each having described well over 1,000 species.[3]

Overview of phylogeny

At the very top level, there is broad agreement on the phylogeny and hence classification of spiders, which is summarized in the cladogram below. The three main clades into which spiders are divided are shown in bold; as of 2015, they are usually treated as one suborder, Mesothelae, and two infraorders, Mygalomorphae and Araneomorphae, grouped into the suborder Opisthothelae.[4][5] The Mesothelae, with about 140 species in 8 genera as of October 2020, make up a very small proportion of the total of around 49,000 known species. Mygalomorphae species comprise around 7% of the total, the remaining 93% being in the Araneomorphae.[note 1]

Araneae (spiders)

Mesothelae

Opisthothelae

Mygalomorphae

Araneomorphae

Hypochiloidea

Austrochiloidea

Haplogynae

Entelegynae

The Araneomorphae are divided into two main groups: the Haplogynae and the Entelegynae. The Haplogynae make up about 10% of the total number of spider species, the Entelegynae about 83%.[note 1] The phylogenetic relationships of the Haplogynae, Entelegynae and the two smaller groups Hypochiloidea and Austrochiloidea remain uncertain as of 2015. Some analyses place both Hypochiloidea and Austrochiloidea outside Haplogynae;[6] others place the Austrochiloidea between the Haplogynae and the Entelegynae;[7][8] the Hypochiloidea have also been grouped with the Haplogynae.[9] Earlier analyses regarded the Hypochiloidea as the sole representatives of a group called the Paleocribellatae, with all other araneomorphs placed in the Neocribellatae.[10]

The Haplogynae are a group of araneomorph spiders with simpler male and female reproductive anatomy than the Entelegynae. Like the mesotheles and mygalomorphs, females have only a single genital opening (gonopore), used both for copulation and egg-laying;[11] males have less complex palpal bulbs than those of the Entelegynae.[12] Although some studies based on both morphology and DNA suggest that the Haplogynae form a monophyletic group (i.e. they comprise all the descendants of a common ancestor),[13][9] this hypothesis has been described as "weakly supported", with most of the distinguishing features of the group being inherited from ancestors shared with other groups of spiders, rather than being clearly indicative of a separate common origin (i.e. being synapomorphies).[14] One phylogenetic hypothesis based on molecular data shows the Haplogynae as a paraphyletic group leading to the Austrochilidae and Entelegynae.[15]

The Entelegynae have a more complex reproductive anatomy: females have two "copulatory pores" in addition to the single genital pore of other groups of spiders; males have complex palpal bulbs, matching the female genital structures (epigynes).[13] The monophyly of the group is well supported in both morphological and molecular studies. The internal phylogeny of the Entelegynae has been the subject of much research. Two groups within this clade contain the only spiders that make vertical orb webs: the Deinopoidea are cribellate – the adhesive properties of their webs are created by packets of thousands of extremely fine loops of dry silk; the Araneoidea are ecribellate – the adhesive properties of their webs are created by fine droplets of "glue". In spite of these differences, the webs of the two groups are similar in their overall geometry.[16] The evolutionary history of the Entelegynae is thus intimately connected with the evolutionary history of orb webs. One hypothesis is that there is a single clade, Orbiculariae, uniting the orb web makers, in whose ancestors orb webs evolved. A review in 2014 concluded that there is strong evidence that orb webs evolved only once, although only weak support for the monophyly of the Orbiculariae.[17] One possible phylogeny is shown below; the type of web made is shown for each terminal node in order of the frequency of occurrence.[18]

Entelegynae

Eresoidea, RTA clade – no web; substrate-defined web

Orbiculariae

Deinopoideaorb web

Nicodamidaeaerial sheet web

Araneoideaorb web; aerial sheet web; cobweb; no web

If this is correct, the earliest members of the Entelegynae made webs defined by the substrate on which they were placed (e.g. the ground) rather than suspended orb webs. True orb webs evolved once, in the ancestors of the Orbiculariae, but were then modified or lost in some descendants.

An alternative hypothesis, supported by some molecular phylogenetic studies, is that the Orbiculariae are paraphyletic, with the phylogeny of the Entelegynae being as shown below.[19]

Entelegynae

Araneoideaorb web; aerial sheet web; cobweb; no web

RTA clade – no web; substrate-defined web

Deinopoidea, Oecobiidaeorb web; substrate-defined web

On this view, orb webs evolved earlier, being present in the early members of the Entelegynae, and were then lost in more groups,[20] making web evolution more convoluted, with different kinds of web having evolved separately more than once.[17] Future advances in technology, including comparative genomics studies,[1] and whole-genome sampling should lead to "a clearer image of the evolutionary chronicle and the underlying diversity patterns that have resulted in one of the most extraordinary radiations of animals".[17]

Suborder Mesothelae

Mesothelae resemble the Solifugae ("wind scorpions" or "sun scorpions") in having segmented plates on their abdomens that create the appearance of the segmented abdomens of these other arachnids. They are both few in number and also limited in geographical range.

Digitally enhanced image of a Sphodros rufipes that shows the nearly perfectly vertical orientation of the fangs, a prime characteristic of the Mygalomorphae.

Suborder Opisthothelae

Suborder Opisthothelae contains the spiders that have no plates on their abdomens. Opisthothelae is divided into two infraorders, Mygalomorphae and Araneomorphae, which can be distinguished by the orientation of their fangs. It can be somewhat difficult on casual inspection to determine whether the fang orientation would classify a spider as a mygalomorph or araneomorph. The spiders that are called "tarantulas" in English are so large and hairy that inspection of their fangs is hardly necessary to categorize one of them as a mygalomorph. Other, smaller, members of this suborder, however, look little different from the araneomorphs. (See the picture of Sphodros rufipes below.) Many araneomorphs are immediately identifiable as such since they are found on webs designed for the capture of prey or exhibit other habitat choices that eliminate the possibility that they could be mygalomorphs.

Infraorder Mygalomorphae

Megaphobema robustum, one of the many kinds of spiders called "tarantulas"

Spiders in infraorder Mygalomorphae are characterized by the vertical orientation of their fangs and the possession of four book lungs.

Infraorder Araneomorphae

Photograph showing orientation of the fangs of the Araneomorphae.

Most, if not all, of the spiders one is likely to encounter in everyday life belong to infraorder Araneomorphae. It includes a wide range of spider families, including the orb-weaver spiders that weave their distinctive webs in gardens, the cobweb spiders that frequent window frames and the corners of rooms, the crab spiders that lurk on flowers waiting for nectar- and pollen-gathering insects, the jumping spiders that patrol the outside walls of buildings, and so on. They are characterized by having fangs whose tips approach each other as they bite, and (usually) having one pair of book lungs.

Classification above families

Spiders were long classified into families that were then grouped into superfamilies, some of which were in turn placed into a number of higher taxa below the level of infraorder. When more rigorous approaches, such as cladistics, were applied to spider classification, it became clear that most of the major groupings used in the 20th century were not supported. Many were based on shared characteristics inherited from the ancestors of multiple clades (plesiomorphies), rather than being distinct characteristics originating in the ancestors of that clade only (apomorphies). According to Jonathan A. Coddington in 2005, "books and overviews published prior to the last two decades have been superseded".[21] Listings of spiders, such as the World Spider Catalog, currently ignore classification above the family level.[21][22]

At the higher level, the phylogeny of spiders is now often discussed using informal clade names, such as the "RTA clade",[23] the "Oval Calmistrum" clade or the "Divided Cribellum" clade.[24] Older names previously used formally are used as clade names, e.g. Entelegynae and Orbiculariae.[25]

Table of families

Key
Genera1≥2≥10≥100
Species1–9≥10≥100≥1000
Spider families[note 2]
FamilyGeneraSpeciesCommon nameExample
Mesothelae
Heptathelidae7107
Liphistiidae162Kimura spider
Opisthothelae: Mygalomorphae
Actinopodidae3118Missulena (mouse spiders)
Anamidae10111Aname diversicolor (black wishbone spider)
Antrodiaetidae437folding trapdoor spidersAtypoides riversi
Atracidae336Australian funnel-web spidersIllawarra wisharti
Atypidae356purseweb spidersSphodros rufipes (red-legged purseweb spider)
Barychelidae40282trapdoor baboon spidersSason sundaicum
Bemmeridae447Spiroctenus personatus
Ctenizidae25cork-lid trapdoor spidersCteniza sauvagesi
Cyrtaucheniidae693wafer trapdoor spidersAmblyocarenum nuragicus
Dipluridae795funnel-web tarantulasSpruce-fir moss spider (Microhexura montivaga)
Entypesidae642Entypesa andohahela
Euagridae1487Euagrus formosanus
Euctenizidae877Aptostichus simus
Halonoproctidae6130Ummidia algarve
Hexathelidae745venomous funnel-web tarantulasHexathele hochstetteri
Hexurellidae14
Idiopidae23437armored trapdoor spidersIdiosoma nigrum (black rugose trapdoor spider)
Ischnothelidae526
Macrothelidae247
Mecicobothriidae12dwarf tarantulas
Megahexuridae11
Microhexuridae12
Microstigmatidae1138Envia garciai
Migidae11103tree trapdoor spidersMoggridgea rainbowi
Nemesiidae10148funnel-web trapdoor spidersAname atra (black wishbone spider)
Paratropididae416baldlegged spidersParatropis tuxtlensis
Porrhothelidae15
Pycnothelidae15137
Rhytidicolidae214Fufius lucasae
Stasimopidae147
Theraphosidae1561039tarantulasGoliath birdeater (Theraphosa blondi)
Opisthothelae: Araneomorphae
Agelenidae901366araneomorph funnel-web spidersHobo spider (Eratigena agrestis)
Amaurobiidae50283tangled nest spidersCallobius claustrarius
Anapidae58232
Anyphaenidae58614anyphaenid sac spidersHibana velox (yellow ghost spider)
Araneidae1843097orb-weaver spidersZygiella x-notata
Archaeidae690pelican spidersMadagascarchaea gracilicollis
Archoleptonetidae28Archoleptoneta gertschi
Arkyidae238
Austrochilidae29Hickmania troglodytes
Caponiidae20139Diploglena capensis
Cheiracanthiidae14363
Cithaeronidae29
Clubionidae19662sac spidersClubiona trivialis
Corinnidae73824dark sac spidersCastianeira sp.
Ctenidae48532wandering spidersPhoneutria fera
Cyatholipidae2358
Cybaeidae21303Diving bell spider (Argyroneta aquatica)
Cycloctenidae880
Deinopidae367net-casting spidersDeinopis subrufa (rufous net-casting spider)
Desidae60296intertidal spidersPhryganoporus candidus
Dictynidae53475Nigma walckenaeri
Diguetidae215coneweb spiders
Drymusidae217false violin spiders
Dysderidae25591woodlouse hunter spidersWoodlouse spider (Dysdera crocata)
Eresidae9102velvet spidersEresus sandaliatus
Filistatidae19189crevice weaversSouthern house spider (Kukulcania hibernalis)
Gallieniellidae541
Gnaphosidae1452430ground spidersDrassodes cupreus
Gradungulidae817large-clawed spidersProgradungula carraiensis (Carrai cave spider)
Hahniidae24353dwarf sheet spiders
Hersiliidae16187tree trunk spidersHersilia savignyi
Homalonychidae12
Huttoniidae11Huttonia palpimanoides
Hypochilidae233lampshade spidersHypochilus thorelli
Lamponidae23192White-tailed spider (Lampona spp.)
Leptonetidae22370Tooth Cave spider (Tayshaneta myopica)
Linyphiidae6244724dwarf / money spidersLinyphia triangularis
Liocranidae35311liocranid sac spiders
Lycosidae1272457wolf spidersLycosa tarantula
Malkaridae1357shield spiders
Mecysmaucheniidae725
Megadictynidae22
Mimetidae8159pirate spidersOarces reticulatus
Miturgidae29141long-legged sac spiders
Myrmecicultoridae11
Mysmenidae14158spurred orb-weavers
Nesticidae18285scaffold web spidersNesticella marapu
Nicodamidae727
Ochyroceratidae10177midget ground weaversTheotima minutissima
Oecobiidae6120disc web spidersOecobius navus
Oonopidae1151888dwarf hunting spidersOonops domesticus
Orsolobidae30188
Oxyopidae9443lynx spidersPeucetia viridans (green lynx spider)
Pacullidae438
Palpimanidae21165palp-footed spiders
Penestomidae19
Periegopidae13
Philodromidae30535philodromid crab spidersPhilodromus dispar
Pholcidae971893daddy long-legs spidersPholcus phalangioides
Phrurolithidae20313
Physoglenidae1372
Phyxelididae1468
Pimoidae285Pimoa cthulhu
Pisauridae51353nursery web spidersPisaura mirabilis
Plectreuridae231
Prodidomidae23192
Psechridae261
Psilodercidae11224
Salticidae6656433jumping spidersZebra spider (Salticus scenicus)
Scytodidae4241spitting spidersScytodes thoracica
Segestriidae5152tubeweb spidersSegestria florentina
Selenopidae9262wall spidersSelenops radiatus
Senoculidae131
Sicariidae3172recluse spidersBrown recluse (Loxosceles reclusa)
Sparassidae951337huntsman spidersDelena cancerides
Stenochilidae213
Stiphidiidae20125sheetweb spidersTartarus mullamullangensis
Symphytognathidae1098dwarf orb-weaversPatu digua
Synaphridae313
Synotaxidae111
Telemidae16104long-legged cave spiders
Tetrablemmidae27151armored spiders
Tetragnathidae46982long jawed orb-weaversLeucauge venusta (orchard spider)
Theridiidae1252538cobweb spidersRedback spider (Latrodectus hasselti)
Theridiosomatidae20135ray spidersTheridiosoma gemmosum
Thomisidae1712167crab spidersMisumena vatia (goldenrod crab spider)
Titanoecidae556Goeldia obscura
Toxopidae1482
Trachelidae20263
Trachycosmidae20148
Trechaleidae20148
Trochanteriidae651
Trogloraptoridae11Trogloraptor marchingtoni
Udubidae415
Uloboridae19291hackled orb-weaversUloborus walckenaerius
Viridasiidae314
Xenoctenidae433
Zodariidae891251ant spidersZodarion germanicum
Zoropsidae27182Zoropsis spinimana

Notes

  1. Species counts from World Spider Catalog (2020, Currently valid spider genera and species), family classification from Coddington (2005, p. 20).
  2. Unless otherwise shown, currently accepted families and counts based on the World Spider Catalog version 22.5 as of 5 November 2021.[26] In the World Spider Catalog, "species" counts include subspecies. Assignment to sub- and infraorders based on Coddington (2005, p. 20) (when given there).

References

Bibliography

  • Agnarsson, Ingi; Coddington, Jonathan A. & Kuntner, Matjaž (2013). "Systematics : Progress in the study of spider diversity and evolution". In Penney, David (ed.). Spider research in the 21st century: trends & perspectives. Manchester, UK: Siri Scientific Press. ISBN 978-0-9574530-1-2.
  • Blackledge, Todd A.; Scharff, Nikolaj; Coddington, Jonathan A.; Szüts, Tamas; Wenzel, John W.; Hayashi, Cheryl Y. & Agnarsson, Ingi (2009). "Reconstructing web evolution and spider diversification in the molecular era". Proceedings of the National Academy of Sciences. 106 (13): 5229–5234. Bibcode:2009PNAS..106.5229B. doi:10.1073/pnas.0901377106. PMC 2656561. PMID 19289848.
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  • Eberhard, W.G. & Huber, B.A. (2010). "Spider genitalia: precise manoeuvers with a numb structure in a complex lock" (PDF). In Leonard, Janet L. & Córdoba-Aguilar, Alex (eds.). The evolution of primary sexual characters in animals. Oxford University Press. ISBN 978-0-19-971703-3. Retrieved 2015-09-20.
  • Griswold, C.E.; Ramirez, M.J.; Coddington, J.A. & Platnick, N.I. (2005). "Atlas of phylogenetic data for entelegyne spiders (Araneae: Araneomorphae: Entelegynae) with comments on their phylogeny" (PDF). Proceedings of the California Academy of Sciences. 56 (Suppl. 2): 1–324. Retrieved 2015-10-11.
  • Hormiga, Gustavo & Griswold, Charles E. (2014). "Systematics, Phylogeny, and Evolution of Orb-Weaving Spiders". Annual Review of Entomology. 59 (1): 487–512. doi:10.1146/annurev-ento-011613-162046. PMID 24160416.
  • Michalik, Peter & Ramírez, Martín J. (2014). "Evolutionary morphology of the male reproductive system, spermatozoa and seminal fluid of spiders (Araneae, Arachnida)–Current knowledge and future directions". Arthropod Structure & Development. 43 (4): 291–322. doi:10.1016/j.asd.2014.05.005. hdl:11336/19081. PMID 24907603.
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  • Ramírez, Martín J. (2014). The morphology and phylogeny of dionychan spiders (Araneae, Araneomorphae). Bulletin of the American Museum of Natural History. Vol. 390. hdl:2246/6537.
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