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, located towards the posterior end; see also Abdomen § Other animalsAccessory claw: Modified at the tip of the in web-building spiders; used with to grip strands of the webAnal tubercle: A small protuberance above the through which the anus opensApodeme: see Apophysis : An outgrowth or process changing the general shape of a body part, particularly the appendages; often used in describing the male : see Atrium : An internal chamber at the entrance to the in female haplogyne spiders

B

Bidentate: Having two Book lungs: Respiratory organs on the ventral side of the, in front of the, opening through narrow slits; see also Book lungsBranchial operculum: see Bulbus: see

C

Calamistrum : Modified setae 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 CalamistrumCaput : see Carapace: A hardened plate covering the upper portion of the ; see also CarapaceCarpoblem: 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, located towards the anterior end, composed of the head and the thorax, the two regions being separated by the ; covered by the and bearing the, legs, and mouthpartsCervical 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 processChelicera : One of two appendages at the front of the, made up of basal portion, the, and the ; sometimes called the jaw; see also CheliceraeCheliceral furrow: A shallow groove on the basal portion of a accommodating the, usually having on its marginsCheliceral tooth: A tooth-like extension on the margin of the Chilum: A small hardened plate at the base of the, under the Claw: see Claw tuft: A dense group of hairs or bristles underneath the paired, usually well developed in hunting spidersClypeus: The area of the between the anterior and the anterior edge of the carapaceColulus: A short protuberance in the middle of the underside of the in front of the, considered to be a modification of the Conductor: see Copulatory duct: An internal tube from the through which sperm enters the female; separate from the duct through which fertilized eggs pass in entelegyne spidersCopulatory 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 insertedCoxa: see Crenulate: Having longitudinal ridgesCribellum: 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 CribellumCuspule: A small spiny outgrowth on the and of MygalomorphaeCymbium : 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 DionychaDorsal groove: see Dorsum: The upper 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; see

E

Ecribellate: see Embolus: see Endite: see Endosternite: An internal hardened plate 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 ; see also EntelegynaeEpigastric furrow or epigastric fold: A transverse slit towards the front of underside of the ; the front pair of open at the edge of this furrow as do the genital openings Epigyne or epigynum : A hardened plate on the underside of the female in which the are located; only fully developed in mature females of spiders; see also EpigyneEyes: The basic number of eyes is eight, typically arranged in two rows ; 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,

F

Falx : A dated term for 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 fangFemur: see Fertilization duct: A duct in female spiders leading from the to the uterusFolium: A broad leaf-like marking along the medial line of the top of the Fossa : A pit or depression, typically in the Fovea : 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: see Gnathocoxa: see 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 GonoporeGravid: A fertilised female with an enlarged abdomen section right before egg laying has begun.

H

Haematodocha : see 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 ; see also HaplogynaeHeart 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 featureLabium : A hardened plate between the at the front of the ; see also Arthropod mouthparts: LabiumLabrum: see Lamella characteristica or just lamella: a sheet-like on the of many Linyphiidae speciesLateral : Viewed from above or below, the sides of the leg or, i.e. the surfaces parallel to the line of sight; see, Laterigrade: With legs directed to the side, hence appearing like and moving like a crab; see 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 is longest and third leg is shortestLeg parts or segments: see Lorum: A set of covering the dorsal surface of the.

M

Main eye: One of the two anterior median eyes that have the light-detecting units pointing towards the source; particularly enlarged in the families Salticidae and Thomisidae; see, Mastidion : A projection or bump on the chelicerae Maxilla : Modified of the, used in feeding; not the structure called by this name in other arthropods, for which see Maxilla (arthropod mouthpart)Metatarsus: see

O

Ocular area or ocular quadrangle: The area of the which includes the.Operculum or branchial operculum : 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 spidersOpisthosoma: see

P

Palp: see Palpal 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 bulbParacymbium: An outgrowth of the on the male Patella: see Paturon: The basal segment of a to which the connectsPedicel or petiolus: The narrow connection between the and Pedipalp : The second appendage of the in front of the first leg; bears the in male spiders; see, see also PedipalpPlumose: Used to describe hairs having outgrowths or appendages on two sides, giving a feather-like appearance; the appendages vary in number, size and arrangementPluridentate: Having multiple Postembryo : The stage of development between hatching from the egg and first moltingPreening brush: a dense cluster of near the tip of the posterior ; called a preening comb when present as a transverse row of setae.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 Promarginal: The side of the facing forward; particularly used for describing ; opposite Prosoma: see

R

Rastellum : An often rake-like structure at end of the in mygalomorph spiders; used in burrowingRebordered: Having a thickened edge ; particularly used of the Receptaculum : see 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 cladeRetromarginal: The side of the facing backward ; particularly used for describing ; opposite Rostrum : A component of the mouthparts, concealed by the ; see also Arthropod mouthparts: Labrum

S

Scape: An elongated process or appendage of some Sclerite: A single hardened part of the external covering Scopula : A brush of hairs ; called a when on the end of the foot, where it improves adhesionScutum : A hardened plate on the of some spidersSecondary eye: An eye belonging to the three pairs – anterior lateral eyes, posterior median eyes and posterior lateral eyes – that are primarily movement detectors and have the light-detecting units pointing away from the source; see, Segments or articles of the legs and :Serrula: A row of tiny teeth along the edge of the Seta : A bristle; spiders have a variety of hair-like structures of increasing size that are referred to as hairs, bristles or Sigillum : 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 AraneomorphaeSperm duct: A duct in the male used to store spermSpermatheca : A structure in the of female spiders used to store sperm after insemination and before fertilization; see also SpermathecaSpigot: A small pointed or cylindrical structure at the tip of a from which silk emergesSpine: 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 or spinesSpinneret: An appendage borne on the, typically one of six arranged in three pairs: anterior, median and posterior ; silk emerges from small on the spinnerets; see also SpinneretSternum: The lower 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 elsewhere on the body creates a soundSubadult: A spider in the last stage of development before becoming a sexually mature adultSubtegulum: see

T

Tapetum : A light-reflecting layer in a making the eye appear paleTarsal 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 twoTarsal organ: a small pit, usually spherical and on the surface of each, believed to respond to humidityTarsus: see Teeth: Pointed growths or bumps along the margins of the Tegulum: see Thoracic furrow: see Tibia: see Trachea : 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 § InvertebratesTrichobothrium : A slender hair-like structure of variable length on the legs and, arising from a special socket; used to detect air movements, including sounds; see, Trochanter: see

U

Unidentate: Having a single tooth

V

Venter : The lower 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; see Vulva: The internal copulatory organs of a female spider, including the,, and

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
  • ITC: inferior tarsal claw →
  • 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
  • STC: superior tarsal claw →
  • VTA: ventral tegular apophysis, on the underside of the
  • VTiA: ventral tibial apophysis, on the lower surface of a