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.

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: see


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


 * 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: see


 * Bulbus: see

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): see


 * 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: see


 * 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: see


 * 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: see


 * 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: see


 * 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; see

E

 * Ecribellate: see


 * Embolus: see


 * Endite: see


 * 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 ; 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; see ,

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: see


 * 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: 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 Gonopore

H

 * Haematodocha (also spelled hematodocha): 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 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: see


 * 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; 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 (leg I) is longest and third leg (leg III) is shortest


 * Leg parts or segments: see

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; see ,


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


 * Maxilla (plural maxillae; 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: see

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: see

P

 * Palp: see




 * 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: see


 * 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, 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


 * 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; 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: see

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 rebordé, e.g. in Levy (1984) ); particularly used of the




 * Receptaculum (plural receptacula): 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 clade


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


 * Rostrum (also called labrum): A component (the "upper lip") of the mouthparts, concealed by the ; see also Arthropod mouthparts: Labrum

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; see ,


 * 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


 * Serrula: A row of tiny teeth along the edge of the


 * 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


 * Subadult: A spider in the last stage of development (penultimate instar) before becoming a sexually mature adult


 * Subtegulum: see

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: see


 * Teeth: Pointed growths or bumps along the margins of the


 * Tegulum: see


 * Thoracic furrow: see


 * Tibia: see


 * 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; see ,


 * Trochanter: see

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; 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