Spiders Terminology

Scientific Name

Explication

Explicatory Drawing
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Abdomen

The posterior (rear) of the two major divisions of a spider

Accessory claws

Serrated, thickened hairs near the true claws in some spiders

Alveolus

A ventral depression in the male palp which receives the basal and middle divisions of the genital bulb. Although usually described as a cup-like depression, the alveolus is actually a ringed depression to the inner margin of which is joined the basal haematodocha

Anal tubercle

A small projection, dorsal to the spinners, carrying the anal opening

Annulations

Rings of pigmentation around leg segments

Anterior

Nearer the front or head

Apex

Apomorphy

Apical

Male palp: the conductor and the embolic subdivision comprise the apical division of the bulb.

Apophysis

An excrescence or appendage changing the general cylindrical or globular shape of a sclerite; most often used in description of male palp.

Internal chamber at the entrance of copulation tract in female haplogyne spiders

Ballooning

Aeronautical dispersing by means of air currents acting on strands of silk

Booklung

An air-filled cavity, containing sacks of blood-filled leaves, opening on the underside of the abdomen

Branchial opperculum

A sclerotized, hairless plate overlying the book lung

Bulbus

The genital bulb is the terminal segment of the palpus. It's an hollow organ with external elaborations. The bulbus is divided into three divisions: (1) Basal division, (2) Middle division and (3) Apical division

Calamistrum

A comb-like series of hairs on metatarsus IV of cribbelate spiders

Another name for the cephalic region of the cephalothorax

Carapace

The exoskeleton covering, or shell, over the dorsal (upper) surface of the cephalothorax

Cardiac mark

An elongate midline mark on the anterior, dorsal surface of the abdomen which overlies the heart

Cephalothorax

The anterior (front) of the two major divisions of the body of a spider

Chelicerae

The jaws, each one comprising a large basal part and an fang

Said of chelicerae in which the fang closes down on a tooth-like process

Small sclerite at the base of chelicerae, just under the clypeus

Chitin

A linear homopolysacheride found as the characteristic molecule in the cuticle of arthropods. The molecules are layered in chains and cross-linked to form a strong, lightweight basis of the cuticle

Claw tuft

A bunch of hairs at the tip of the leg tarsus in spiders with only two claws

Clypeus

The area between the anterior row of eyes and the anterior edge of the carapace

Colulus

A small midline appendage or tubercle arising just in front of the anterior spinners in some spiders

Conductor

A semi-membranous structure in the male palp which supports and guides the embolus in insemination

Condyle

A smooth, rounded protuberance sometimes present on the outer side of the chelicera, near its base

Coxa (plural: Coxae)

The segment of legs nearest the body; modified in the palp to form the maxilla

Cribellum

A spinning organ just in front of the spinners which appears as a transverse plate. Only present in cribellate spiders, which also have a calamistrum

Cymbium

The broadened, hollowed-out tarsus of the male palp within which the palpal organs are attached

Said of chelicerae extending downwards with fangs closing towards midline

Possessing two claws on tarsus

Distal

Pertaining to the outer end, furthest away from the body or point of attachment

Dorsal

Pertaining to the upper surface

Dorsum

The upper surface

Ecdysis

Moulting; the periodic casting off the cuticle

Without teeth

Embolus

The structure, in the male palp, containing the terminal part of the ejaculatory duct and its opening. It may be very small, or long, whip-like or coiled and is sometimes divided into several structures

Basal segment of palp, also called the maxilla or gnathocoxa

Entelegyne

The group of spiders in which the females have an epigyne

Epigastric fold

A fold and groove separating the anterior part of the ventral abdomen (with epigyne and book lungs) from the posterior part

Epigyne

A more or less sclerotized and modified external structure associated with the reproductive openings of adult females of most spiders

Exoskeleton

The hard ,external, supportive covering found in all arthropods

Exuviae

The parts of cuticle cast off during moulting

Fang

The claw-like part of each chelicera; the poison duct opens near its tip

Femur (pl. femora, adj. femoral)

The third segment of the leg, counting from the body

Teeth having more than one point

Folium

Any pattern of pigment on the dorsum of the abdomen which is fairly broad and leaf-shaped

Fovea

A short median groove on the thoracic part of the carapace which marks the internal attachment of the gastric muscles

Gnathocoxa (pl. gnathocoxae)

Basal segment of palp, also called maxilla or endite

Gossamer

A light film of silk threads, or groups of these floating through the air

Haematodocha

A balloon of elastic connective tissue between groups of sclerites in the male palp which distends with blood during insemination causing the sclerites to separate and rotate

Haplogyne

The group of spiders in which the females have no epigyne

Head

The part of the carapace carrying the eyes which is separated from the thorax by a shallow groove

Labium

The lip, under the mouth opening and between the maxillae, attached to the front of the sternum

Lateral

Pertaining to the side

Lanceolata

Tapering to a point

Lyriform organ

A sensory organ near the distal end of limb segments formed of a group of parallel slit organs

Maxilla

The mouthparts on each side of the labium which are the modified coxae of the palps

Median

In the midline or in the middle

Median apophysis

An sclerite arising from the middle division of the male palpal organs

Median septum

Longitudinal sclerite on floor of epigynal atrium

Metatarsus (pl. Metatarsi)

The sixth segment of the leg, counting from the body

Ventral extension of tip of tarsus bearing the claws

Orb web

A two dimensional web, roughly circular in design (and strictly speaking, a misnomer). Silk threads radiate like spokes from a central hub. These are then overlaid with a spiral of silk, running from the periphery almost to the hub.

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Palp

Short for the pedipalp. The appendage arising just in front of the legs, the coxa of which also forms the maxilla. It has no metatarsal segment and in adult males is greatly modified for the transfer of semen

Palpal organs

The more or less complex structures found in the terminal part of the adult male palp. They comprise groups of sclerites separated from each other and the cymbium by up to three haematodochae and contain the semen reservoir which opens via ducts through the tip of the embolus

Paracymbium

A structure in the male palp branching from, or loosely attached to, the cymbium

Said of chelicera extending forwards, with fangs closing towards abdomen

Patella(pl. Patellae)

The fourth segment of the leg or palp, counting from the body

Pedicel

The narrow stalk connecting the cephalothorax and the abdomen

Pheromone

A chemical secreted by an animal in minute amounts which brings about a behavioural response in another, often of the opposite sex

Phylogenetic

Pertaining to evolutionary relationships between and within groups

Having more than one tooth

Said of chelicera directed forwards

Posterior

Near the rear end

Process

A projection from the main structure

Procurved

Curved as an arc having its ends ahead of its centre

Prolateral

Projecting from, or on, the side facing forwards

Proximal

Pertaining to the inner end; closest to the body or point of attachment

Punctate

Covered with tiny depressions

Rastellum (pl. rastella)

Rake-like structure at extremity of chelicerae in Mygalomorpha, often reduced to a few strong spines; use for burrowing

Recurved

Curved as an arc having its ends behind its centre

Reticulated

Like network

Retrolateral

Projecting from, or on, the side facing backwards

Rugose

Rough, wrinkled

Scape (Scapus)

A finger-, tongue-, or lip-like projection from the midline of the female epigyne

Sclerite

Any separate sclerotized structure connected to the other structures by membranes

Sclerotized

Hardened or horny; not flexible or membranous

Scopula (pl. Scopulae)

A brush of hairs on the underside of the tarsus and metatarsus in some spiders

Scutum

A hard, often shiny, sclerotized plate on the abdomen of some spiders

Septum

A partition separating two cavities or parts

Serrated

Saw-toothed

Seta (pl. setae)

Hair-like, tapered and flexible structures on legs and body (cf. spine and trichobothrium)

Sigillum (pl. Sigila)

An impressed, sclerotized spot, often reddish-brown. Often present on the dorsal surface of the abdomen and marking points of internal muscle attachments

Slit organ

A stress receptor in the exoskeleton

Spermathecae

The sacs or cavities in female spiders which receive and store semen

Spiderling

The nymphal or immature spider, generally resembling the adult, but smaller; fully mobile and no longer dependant on yolk

Spine

A thick, stiff hair or bristle

Spinners

Paired appendages at the rear end of the abdomen, below the anal tubercle, from the spigots of which silk strands are extruded

Spiracle

The opening of the tracheae on the underside eof the abdomen

Sternum

The heart-shaped or oval exoskeletal shield covering the under surface of the cephalothorax

Stria (pl. striae)

Paired depressions; usually three pairs of darkened stripes radiating from fovea

Stridulating organ

A file-and-scraper for sound production; may be variously located on chelicerae, palps, legs, abdomen and carapace

Subadult

Almost adult; the last instar before maturity

Synonym

Each of two or more scientific names of the same rank used to denote the same taxon. The senior synonym is the name first established

A light-reflecting layer in secondary eyes; eyes appear pale in colour; assumed to be used for nocturnal vision

Tarsus (pl. Tarsi)

The most distal (or end) segment of a leg or palp

Taxon

Any taxonomic unit (e.g. family, genus, species)

Taxonomy

The theory and practice of classifying organisms; part of systematics, the study of the kinds and diversity of organisms

Tegulum

Part of the male palp: a discoidal sclerite

External cuticular skin

Thorax

That part of the cephalothorax behind the head region and separated from it by a shallow groove

Tibia (pl. Tibiae)

The fifth segment of the leg or palp counting from the body

Tracheae

Tubes through which air is carried around the body and which open at the spiracles

Trichobothrium (pl. Trichobotria)

A long, fine hair rising almost vertically from a socket on the leg. Trichobothria detect air vibrations and currents

Trochanter

The second segment of the leg or palp, counting from the body

Unidentate

Having one tooth

Ventral

Pertaining to the underside

Vulva

Internal structure of female copulatory organs, including entrance ducts, spermathecae and fertilisation ducts (in entelegyne spiders); internal genitalia including ducts and spermathecae (in haplogyne spiders)