Glossary of spider terms

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

Links within the glossary are shown .

Terms

A

Abdomen or opisthosoma: One of the two main body parts ( tagmata), located towards the posterior end; see also Abdomen § Other animals

Accessory claw: Modified at the tip of the in web-building spiders; used with to grip strands of the web

Anal tubercle: A small protuberance (tubercule) above the through which the anus opens

Apodeme →

Apophysis (plural apophyses): An outgrowth or process changing the general shape of a body part, particularly the appendages; often used in describing the male →

Atrium (plural atria): An internal chamber at the entrance to the in female haplogyne spiders

B

Bidentate: Having two

Book lungs: Respiratory organs on the ventral side (underside) of the , in front of the , opening through narrow slits; see also Book lungs

Branchial operculum →

Bulbus →

C

Calamistrum (plural calamistra): Modified setae (bristles) on the of the fourth leg of spiders with a , arranged in one or more rows or in an oval shape, used to comb silk produced by the cribellum; see also Calamistrum

Caput (plural capita) →

Carapace: A hardened plate (sclerite) covering the upper (dorsal) portion of the ; see also Carapace

Carpoblem: The principal on the male ; also just called the tibial apophysis

Cephalic region or caput: The front part of the , separated from the thoracic region by the

Cephalothorax or prosoma: One of the two main body parts ( tagmata), located towards the anterior end, composed of the head ( or caput) and the thorax (thoracic region), the two regions being separated by the ; covered by the and bearing the , legs, and mouthparts

Cervical groove: A shallow U-shaped groove, separating the and thoracic regions of the

Chelate: A description of a where the closes against a tooth-like process

Chelicera (plural chelicerae): One of two appendages at the front of the , made up of basal portion, the , and the ; sometimes called the jaw; see also Chelicerae

Cheliceral furrow: A shallow groove on the basal portion of a accommodating the , usually having on its margins

Cheliceral tooth: A tooth-like extension on the margin of the

Chilum: A small hardened plate (sclerite) at the base of the , under the

Claw →

Claw tuft: A dense group of hairs or bristles (setae) underneath the paired , usually well developed in hunting spiders

Clypeus: The area of the between the anterior (frontmost) and the anterior edge of the carapace

Colulus: A short protuberance in the middle of the underside of the in front of the , considered to be a modification of the

Conductor →

Copulatory duct: An internal tube (duct) from the through which sperm enters the female; separate from the duct through which fertilized eggs pass in entelegyne spiders

Copulatory opening: An opening in the ventral of female spiders; in entelegyne spiders, a double opening in the through which the is inserted; in haplogyne spiders, a single opening through which male is inserted

Coxa →

Crenulate: Having longitudinal ridges

Cribellum: A sieve-like plate in front of the , used in conjunction with the ; spiders with a cribellum are called cribellate, those without ecribellate; see also Cribellum

Cuspule: A small spiny outgrowth ("wart") on the and of Mygalomorphae

Cymbium (plural cymbia): The end part of the of the in a mature male, usually hollowed out and bearing the

D

Dionychous: With two on the of each leg; a feature of spiders in the clade Dionycha

Dorsal groove →

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

E

Ecribellate →

Embolus →

Endite →

Endosternite: An internal hardened plate (sclerite)

Entelegyne: A spider whose female has an and separate ducts leading to for sperm storage and to the uterus for fertilization, creating a "flow-through" system; → ; see also Entelegynae

Epigastric furrow or epigastric fold: A transverse slit towards the front (anterior) of underside of the ; the front pair of open at the edge of this furrow as do the genital openings ()

Epigyne or epigynum (plural epigynes): A hardened plate on the underside of the female in which the are located; only fully developed in mature females of spiders; see also Epigyne

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 → ,

F

Fang: The final hinged part of the , 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

Femur →

Fertilization duct: A duct in female spiders leading from the to the uterus

Folium: A broad leaf-like marking along the medial line of the top of the

Fossa (plural fossae): A pit or depression, typically in the

Fovea (also called thoracic furrow or dorsal groove): A depression or pit in the centre of the of a spider marking an inward projection of the exoskeleton to which stomach muscles are attached

G

Genital opening →

Gnathocoxa →

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; see also Gonopore

H

Haematodocha →

Haplogyne: A spider whose female lacks an and in which the same ducts are used to transport sperm to the uterus and to the ; → ; see also Haplogynae

Heart mark: A narrow marking along the top of the roughly corresponding to the location of the heart

L

Labio-sternum mound: A mound separating the from the , found in some tarantulas, where it can be a diagnostic feature

Labium (plural labia): A hardened plate (sclerite) between the at the front of the ; see also Arthropod mouthparts: Labium

Labrum (plural labra): A component (the "upper lip") of the mouthparts, concealed by the ; see also Arthropod mouthparts: Labrum

Lateral (applied to appendages): Viewed from above or below, the sides of the leg or , i.e. the surfaces parallel to the line of sight; → ,

Laterigrade: With legs directed to the side, hence appearing like and moving like a crab; →

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

Leg parts or segments →

M

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; → ,

Mastidion (plural mastidia): A projection or bump on the chelicerae (not to be confused with )

Maxilla (also called endite or gnathocoxa): Modified of the , used in feeding; not the structure called by this name in other arthropods, for which see Maxilla (arthropod mouthpart)

Metatarsus →

O

Operculum or branchial operculum (plural opercula): One of the plates on the surface of the , just in front of the , covering the , often pale, yellow or orange in colour; two pairs in Mygalomorphae, one pair in other spiders

Opisthosoma →

P

Palp →

Palpal bulb (also called bulbus, palpal organ, genital bulb): The copulatory organ of the male spider, carried on the modified last segment of the , used to transfer sperm to the female; see also Palpal bulb

:Conductor: A part of the palpal bulb that accompanies and supports the embolus

:Embolus: The final part of the palpal bulb containing the end of the sperm duct, usually thin, sharp-tipped and strongly hardened (sclerotized)

:Haematodocha (plural haematodochae): A membranous, inflatable part of the palpal bulb

: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

Paracymbium: An outgrowth of the on the male

Patella →

Paturon: The basal segment of a to which the connects

Pedicel or petiolus: The narrow connection between the and

Pedipalp (plural pedipalps or pedipalpi; also called just palp): The second appendage of the in front of the first leg; bears the in male spiders; → , see also Pedipalp

Plumose: Used to describe hairs () having outgrowths or appendages on two sides, giving a feather-like appearance; the appendages vary in number, size and arrangement

Pluridentate: Having multiple

Procurved: Used to describe a structure which is curved in such a way that the outer edges are in front of the central part; opposite

Prolateral: Viewed from above or below, the side of a leg or nearest the mouth, i.e. the side facing forward; opposite (includes diagram)

Promarginal: The side of the facing forward; particularly used for describing ; opposite

Prosoma →

R

Rastellum (plural rastella): An often rake-like structure at end of the in mygalomorph spiders; used in burrowing

Rebordered: Having a thickened edge (i.e. border) (more rarely seen as reborded, from the French , e.g. in Levy (1984)); particularly used of the

Receptaculum (plural receptacula) →

Recurved: Used to describe a structure which is curved in such a way that the outer edges are behind the central part; opposite

Retrolateral: Viewed from above or below, the side of a leg or furthest from the mouth, i.e. the side facing backwards; opposite

Retrolateral tibial apophysis: A backward-facing projection on the tibia of the male ; distinguishing feature of the RTA clade

Retromarginal: The side of the facing backward (towards the posterior end of the spider); particularly used for describing ; opposite

S

Scape: An elongated process or appendage of some

Sclerite: A single hardened (sclerotized) part of the external covering (tegument, exoskeleton)

Scopula (plural scopulae): A brush of hairs (setae); called a when on the end of the foot (tarsus), where it improves adhesion

Scutum (plural scuta): A hardened (sclerotized) plate on the 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; → ,

Segments or articles of the legs and :

:Coxa (plural coxae): First leg segment, between body and trochanter; the coxa of the is heavily modified to form the 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

:Tarsus (plural tarsi; also called telotarsus): Seventh (last) leg segment, after the metatarsus

Seta (plural setae): A bristle; spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles (setae) or

Sigillum (plural sigilla): A circular indentation on the outside of the spider, showing where an internal muscle is attached; particularly on the in some Mygalomorphae and on the in some Araneomorphae

Sperm duct: A duct in the male used to store sperm

Spermatheca (plural spermathecae; also called receptulacum, receptulacum seminis): A structure in the of female spiders used to store sperm after insemination and before fertilization; see also Spermatheca

Spigot: A small pointed or cylindrical structure at the tip of a from which silk emerges

Spine: A pointed, rigid structure on body and legs, usually with a basal joint; spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles (setae) or spines

Spinneret: An appendage borne on the , 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 on the spinnerets; see also Spinneret

Sternum: The lower (ventral) portion of the

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

Subtegulum →

T

Tapetum (plural tapeta): A light-reflecting layer in a making the eye appear pale

Tarsal claw (claw): One of a set of claws at the tip of the ; there may be a single pair, often concealed in a , or an additional third central claw, much smaller than the other two

Tarsal organ: a small pit, usually spherical and on the surface of each , believed to respond to humidity

Tarsus →

Teeth: Pointed growths or bumps along the margins of the

Tegulum →

Thoracic furrow →

Tibia →

Trachea (plural tracheae): A thin hardened internal tube, part of the respiratory system in many araneomorph spiders; opens on the underside of the via a tracheal spiracle; see Trachea § Invertebrates

Trichobothrium (plural trichobothria): A slender hair-like structure of variable length on the legs and , arising from a special socket; used to detect air movements, including sounds; → ,

Trochanter →

U

Unidentate: Having a single tooth

V

Venter (or ventrum): The lower (ventral) portion or surface of the body or ; the adjective ventral may be applied to the lower portion or surface of any part of the body; →

Abbreviations

Some abbreviations commonly found in descriptions of spider anatomy include:

*ALE: anterior lateral eyes →
*ALS: anterior lateral spinnerets →
*AME: anterior median eyes →
*DTA: dorsal tegular apophysis, on the back of the
*DTiA: dorsal tibial apophysis, on the back of a
*LTA: lateral tegular apophysis'', apophysis'' on the side of the
*MOQ: median ocular quadrangle, the quadrangle formed by the four median eyes, →
*PLE: posterior lateral eyes →
*PLS: posterior lateral spinnerets →
*PME: posterior median eyes →
*PMS: posterior median spinnerets →
*RCF: retrolateral cymbial fold, fold on the surface of the
*RTA: retrolateral tibial apophysis, on the surface of a
*VTA: ventral tegular apophysis, on the underside of the
*VTiA: ventral tibial apophysis, on the lower surface of a

See also

* Spider anatomy
* Glossary of entomology terms
* Anatomical terms of location

References

Bibliography

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* {{cite book , editor1-last=Ubick , editor1-first=Darrell , editor2-last=Paquin , editor2-first=Pierre , editor3-last=Cushing , editor3-first=Paula E. , editor4-last=Roth , editor4-first=Vincent , title=Spiders of North America: An Identification Manual , date=2009 , publisher=American Arachnological Society , isbn=978-0977143900 , edition=1st

Spider terms