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Glossary of spider terms

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This glossary describes the terms used in formal descriptions of spiders; where applicable these terms are used in describing other arachnids.

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Terms

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A

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The underside and head of a female ecribellate entelegyne spider
  • Accessory claw: Modified setae at the tip of the tarsus in web-building spiders; used with tarsal claws to grip strands of the web[1]
  • Anal tubercle: A small protuberance (tubercule) above the spinnerets through which the anus opens[2]
  • Apophysis (plural apophyses): An outgrowth or process changing the general shape of a body part, particularly the appendages; often used in describing the male pedipalp:[2] see retrolateral tibial apophysis

B

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C

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  • Calamistrum (plural calamistra): Modified setae (bristles) on the metatarsus of the fourth leg of spiders with a cribellum, arranged in one or more rows or in an oval shape, used to comb silk produced by the cribellum; see also Calamistrum
  • Cervical groove: A shallow U-shaped groove, separating the cephalic and thoracic regions of the carapace[3]
  • Chelate: A description of a chelicera where the fang closes against a tooth-like process[1]
  • Chelicera (plural chelicerae): One of two appendages at the front of the carapace, made up of basal portion, the paturon, and the fang;[5] sometimes called the jaw; see also Chelicerae
  • Cheliceral furrow: A shallow groove on the basal portion of a chelicera accommodating the fang, usually having teeth on its margins[6]
  • Claw tuft: A dense group of hairs or bristles (setae) underneath the paired tarsal claws, usually well developed in hunting spiders[6]
The clypeus of this jumping spider is covered with red scales.
  • Clypeus: The area of the carapace between the anterior (frontmost) eyes and the anterior edge of the carapace[6]
  • Colulus: A short protuberance in the middle of the underside of the abdomen in front of the spinnerets, considered to be a modification of the cribellum[6]
  • Copulatory duct: An internal tube (duct) from the copulatory opening through which sperm enters the female; separate from the duct through which fertilized eggs pass in entelegyne spiders[8]
  • Crenulate: Having longitudinal ridges[7]
  • Cribellum: A sieve-like plate in front of the spinnerets, used in conjunction with the calamistrum; spiders with a cribellum are called cribellate, those without ecribellate;[4] see also Cribellum

D

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  • Dorsum: The upper (dorsal) portion or surface of the body or abdomen; the adjective dorsal may be applied to the upper portion or surface of any part of the body; see ventrum

E

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  • Endosternite: An internal hardened plate (sclerite)[9]
  • Entelegyne: A spider whose female has an epigyne and separate ducts leading to spermathecae for sperm storage and to the uterus for fertilization,[6] creating a "flow-through" system; see haplogyne; see also Entelegynae
Basic arrangement of spider eyes, viewed from above
Arrangement of eyes in most Salticidae, viewed from above
  • Epigastric furrow or epigastric fold: A transverse slit towards the front (anterior) of underside of the abdomen; the front pair of book lungs open at the edge of this furrow as do the genital openings (gonopores)[10]
  • Eyes: The basic number of eyes is eight, typically arranged in two rows (e.g. as in Gnaphosidae); the front row are the anterior eyes, the row behind the posterior eyes; the four eyes to the edges are the lateral eyes, the four eyes in the centre the median eyes; the anterior median eyes are called the main eyes or direct eyes, while the other eyes are called the secondary eyes or indirect eyes; the number of eyes, their sizes and arrangement varies widely and is characteristic of spider families; see main eye, secondary eye

F

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  • Fang: The final hinged part of the chelicera, normally folded down into a groove in the basal part of the chelicera; venom is injected via an opening near the tip of the fang[11]
Larinioides cornutus spider showing folium on abdomen
  • Folium: A broad leaf-like marking along the medial line of the top of the abdomen
  • Fossa (plural fossae): A pit or depression, typically in the epigyne[12]
  • Fovea (also called thoracic furrow or dorsal groove): A depression or pit in the centre of the carapace of a spider marking an inward projection of the exoskeleton to which stomach muscles are attached[13][14]

G

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  • Gonopore: The genital opening; located in the epigastric furrow; the opening of the duct from the uterus in females and from the testes in males;[9] see also Gonopore

H

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  • Haematodocha (also spelled hematodocha): see palpal bulb
  • Heart mark: A narrow marking along the top of the abdomen roughly corresponding to the location of the heart

L

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  • Labio-sternum mound: A mound separating the labium from the sternum, found in some tarantulas, where it can be a diagnostic feature[16]
  • Lateral (applied to appendages): Viewed from above or below, the sides of the leg or pedipalp, i.e. the surfaces parallel to the line of sight; see prolateral, retrolateral
  • Laterigrade: With legs directed to the side, hence appearing like and moving like a crab;[17] see prograde
  • Leg formula: The legs are numbered from the front from I to IV; the relative length of the legs can be represented by four numbers from the longest to the shortest; e.g. 1423 = first leg (leg I) is longest and third leg (leg III) is shortest[17]

M

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  • Main eye: One of the two anterior median eyes (AME) that have the light-detecting units (rhabdomeres) pointing towards the source; particularly enlarged in the families Salticidae and Thomisidae;[18] see secondary eye, eyes
  • Mastidion (plural mastidia): A projection or bump on the chelicerae (not to be confused with teeth)

O

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P

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Highly simplified and stylized diagram of the main parts of an inflated palpal bulb, based loosely on Coddington (1990);[19] hardened parts shown darker, membranous parts shown lighter
  • Palpal bulb (also called bulbus, palpal organ, genital bulb): The copulatory organ of the male spider, carried on the modified last segment of the pedipalp, used to transfer sperm to the female;[20] see also Palpal bulb
  • Conductor: A part of the palpal bulb that accompanies and supports the embolus[6]
  • Embolus: The final part of the palpal bulb containing the end of the sperm duct, usually thin, sharp-tipped and strongly hardened (sclerotized)[6]
  • Haematodocha (plural haematodochae): A membranous, inflatable part of the palpal bulb[10]
  • Median apophysis: A projection (apophysis) of the palpal bulb, below the conductor
  • Subtegulum: A hardened part of the palpal bulb nearer its base than the tegulum
  • Tegulum: The main hardened part of the palpal bulb
  • Plumose: Used to describe hairs (setae) having outgrowths or appendages on two sides, giving a feather-like appearance; the appendages vary in number, size and arrangement[23]
  • Pluridentate: Having multiple teeth
  • Postembryo (also called larva): The stage of development between hatching from the egg and first molting
  • Procurved: Used to describe a structure which is curved in such a way that the outer edges are in front of the central part;[22] opposite recurved
  • Prolateral: Viewed from above or below, the side of a leg or pedipalp nearest the mouth, i.e. the side facing forward; opposite retrolateral (includes diagram)

R

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  • Rastellum (plural rastella): An often rake-like structure at end of the chelicera in mygalomorph spiders; used in burrowing[22]
  • Rebordered: Having a thickened edge (i.e. border)[24] (more rarely seen as reborded, from the French rebordé, e.g. in Levy (1984)[25]); particularly used of the labium
Terminology of appendage surfaces
  • Recurved: Used to describe a structure which is curved in such a way that the outer edges are behind the central part;[22] opposite procurved
  • Retrolateral: Viewed from above or below, the side of a leg or pedipalp furthest from the mouth, i.e. the side facing backwards; opposite prolateral
  • Retrolateral tibial apophysis: A backward-facing projection on the tibia of the male pedipalp; distinguishing feature of the RTA clade
  • Retromarginal: The side of the cheliceral furrow facing backward (towards the posterior end of the spider); particularly used for describing teeth; opposite promarginal

S

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  • Scape: An elongated process or appendage of some epigyne[26]
  • Sclerite: A single hardened (sclerotized) part of the external covering (tegument, exoskeleton)[24]
  • Scopula (plural scopulae): A brush of hairs (setae); called a claw tuft when on the end of the foot (tarsus), where it improves adhesion[22][27]
  • Scutum (plural scuta): A hardened (sclerotized) plate on the abdomen of some spiders
  • Secondary eye: An eye belonging to the three pairs – anterior lateral eyes (ALE), posterior median eyes (PME) and posterior lateral eyes (PLE) – that are primarily movement detectors and have the light-detecting units (rhabdomeres) pointing away from the source;[28] see main eye, eyes
Pedipalp and leg of a female spider from the underside; the coxa of the pedipalp is heavily modified to form the maxilla
  • Segments or articles of the legs and pedipalps:
  • Coxa (plural coxae): First leg segment, between body and trochanter; the coxa of the pedipalp is heavily modified to form the maxilla or endite
  • Trochanter: Second leg segment, between coxa and femur
  • Femur (plural femora): Third leg segment, between trochanter and patella
  • Patella (plural patellae): Fourth leg segment, between femur and tibia
  • Tibia (plural tibiae): Fifth leg segment, between patella and metatarsus
  • Metatarsus (plural metatarsi; also called basitarsus): Sixth leg segment, between tibia and tarsus; absent in the pedipalp
  • Tarsus (plural tarsi; also called telotarsus): Seventh (last) leg segment, after the metatarsus
  • Serrula: A row of tiny teeth along the edge of the maxilla
  • Seta (plural setae): A bristle;[22] spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles (setae) or spines[29]
  • Spermatheca (plural spermathecae; also called receptulacum, receptulacum seminis): A structure in the abdomen of female spiders used to store sperm after insemination and before fertilization;[22] see also Spermatheca
  • Spigot: A small pointed or cylindrical structure at the tip of a spinneret from which silk emerges[22]
  • Spine: A pointed, rigid structure on body and legs, usually with a basal joint;[31] spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles (setae) or spines[29]
  • Spinneret: An appendage borne on the abdomen, typically one of six arranged in three pairs: anterior (anterior median, AMS), median (posterior median, PMS) and posterior (posterior lateral, PLS); silk emerges from small spigots on the spinnerets;[31][1] see also Spinneret
  • Stridulating organ: A series of thin ridges on a hardened part of the body; rubbing this with a matching series of short, stiff bristles (setae) elsewhere on the body creates a sound[31]
  • Subadult: A spider in the last stage of development (penultimate instar) before becoming a sexually mature adult

T

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  • Tapetum (plural tapeta): A light-reflecting layer in a secondary eye making the eye appear pale[31]
  • Tarsal claw (claw): One of a set of claws at the tip of the tarsus; there may be a single pair, often concealed in a claw tuft, or an additional third central claw, much smaller than the other two[31]
  • Tarsal organ: a small pit, usually spherical and on the dorsal surface of each tarsus, believed to respond to humidity[32]
  • Thoracic furrow: see fovea
  • Trichobothrium (plural trichobothria): A slender hair-like structure of variable length on the legs and pedipalps, arising from a special socket; used to detect air movements, including sounds;[34] see seta, spine

U

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  • Unidentate: Having a single tooth

V

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  • Venter (or ventrum): The lower (ventral) portion or surface of the body or abdomen; the adjective ventral may be applied to the lower portion or surface of any part of the body; see dorsum
  • Vulva: The internal copulatory organs of a female spider, including the copulatory ducts, spermathecae, and fertilization ducts[33]

Abbreviations

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Some abbreviations commonly found in descriptions of spider anatomy include:

See also

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References

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  1. ^ a b c d e f g Jocqué & Dippenaar-Schoeman (2007), p. 20.
  2. ^ a b c Saaristo (2010), p. 13.
  3. ^ a b c d Saaristo (2010), p. 14.
  4. ^ a b Saaristo (2010), pp. 14–15.
  5. ^ Saaristo (2010), pp. 15, 18.
  6. ^ a b c d e f g h i j k l Saaristo (2010), p. 15.
  7. ^ a b c d Jocqué & Dippenaar-Schoeman (2007), p. 21.
  8. ^ Foelix (2011), pp. 230–231.
  9. ^ a b Jocqué & Dippenaar-Schoeman (2007), p. 22.
  10. ^ a b c d e f Saaristo (2010), p. 17.
  11. ^ Foelix (2011), p. 21.
  12. ^ Ubick et al. (2009), p. 265.
  13. ^ Roberts (1995), pp. 13–14.
  14. ^ a b Foelix (2011), pp. 17–18.
  15. ^ Saaristo (2010), p. 16.
  16. ^ Smith (1990).
  17. ^ a b c Jocqué & Dippenaar-Schoeman (2007), p. 23.
  18. ^ Foelix (2011), pp. 102–103.
  19. ^ Coddington, J.A. (1990). "Ontogeny and homology in the male palpus of orb-weaving spiders and their relatives, with comments on phylogeny (Araneoclada: Araneoidea, Deinopoidea)". Smithsonian Contributions to Zoology. 496 (496): 1–52. doi:10.5479/si.00810282.496. Figs 5–8{{citation}}: CS1 maint: postscript (link)
  20. ^ Foelix (2011), pp. 226–227.
  21. ^ Saaristo (2010), pp. 18–19.
  22. ^ a b c d e f g h i j k Saaristo (2010), p. 18.
  23. ^ Zakharov, Boris & Ovtsharenko, Vladimir (2015). "The covering setae of ground spiders (Araneae: Gnaphosidae)" (PDF). Arachnologische Mitteilungen. 49: 34–46. doi:10.5431/aramit4904. Archived from the original (PDF) on 2017-09-28. Retrieved 2017-09-28.
  24. ^ a b c d Jocqué & Dippenaar-Schoeman (2007), p. 24.
  25. ^ Levy, G. (1984). "The Spider Genera Singa and Hypsosinga (Araneae, Araneidae) in Israel". Zoologica Scripta. 13 (2): 121–133. doi:10.1111/j.1463-6409.1984.tb00029.x. S2CID 84218389.
  26. ^ Ubick et al. (2009), p. 271.
  27. ^ Foelix (2011), p. 27.
  28. ^ Foelix (2011), pp. 103–104.
  29. ^ a b Foelix (2011), pp. 84–101.
  30. ^ Foelix (2011), pp. 41, 43.
  31. ^ a b c d e Saaristo (2010), p. 19.
  32. ^ Foelix (2011), p. 36.
  33. ^ a b Jocqué & Dippenaar-Schoeman (2007), p. 26.
  34. ^ Foelix (2011), pp. 89–92.

Bibliography

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  • Comstock, John Henry (1920) [First published 1912]. The Spider Book. Doubleday, Page & Company.
  • Foelix, Rainer F. (2011). Biology of Spiders (3rd p/b ed.). Oxford University Press. ISBN 978-0-19-973482-5.
  • Jocqué, R. & Dippenaar-Schoeman, A.S. (2007). Spider Families of the World (PDF) (2nd ed.). Tervuren (Belgium): Royal Museum for Central Africa. Retrieved 2019-07-04.
  • Roberts, Michael J. (1995). Spiders of Britain & Northern Europe. London: HarperCollins. ISBN 978-0-00-219981-0.
  • Saaristo, M.I. (2010). "Araneae". In Gerlach, J. & Marusik, Y. (eds.). Arachnida and Myriapoda of the Seychelles Islands. Manchester, UK: Siri Scientific Press. pp. 8–306. ISBN 978-0-9558636-8-4.
  • Smith, A.M. (1990). Baboon spiders: Tarantulas of Africa and the Middle East. London: Fitzgerald Publishing.
  • Ubick, Darrell; Paquin, Pierre; Cushing, Paula E.; Roth, Vincent, eds. (2009). Spiders of North America: An Identification Manual (1st ed.). American Arachnological Society. ISBN 978-0977143900.
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