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abdomen (see opisthosoma)
aculeus the curved stinger arising distally from the telson vesicle.  The aculeus is hollow and bears a small distal opening to allow venom from the internal venom glands of the vesicle to be injected for predation or defense.
basal pectinal piece a rectangular plate on the underside of mesosomal segment II to which the pectines attach.
basitarsus the proximal portion of the tarsus, located between the tibia and telotarsus.
book lungs

 the internal respiratory structures of scorpions. 

carapace the dorsal plate of the cephalothorax, bearing the lateral and median eyes.
carinae cuticular ridges on body surfaces, often associated with attachment of internal musculature.  The strength and granulation of carinae are of considerable taxonomic importance.
cephalothorax (see prosoma)
chela the pincer of the pedipalp, comprising the chela palm and the fixed and movable fingers.
chelicerae the anteriormost set of appendages in the scorpion, comprising the mouthparts.  The chelicerae of scorpions are chelate and
chitin a structural polysaccharide that makes up the bulk of the scorpion cuticle.  Added to chitin are a variety of other substances, such as proteins (sclerotized and unsclerotized) and waxes which give special properties to the cuticle.
coxa the proximal segment of the appendage (chelicera, pedipalp, leg) which joins the appendage to the body.  The coxae in modern scorpions, together with the sternum, make up the coxosternal region on the underside of the cephalothorax.
cuticle the nonliving portion of the scorpion's integument, secreted by the underlying epidermis.  The cuticle is a distinctly layered structure made of chitin, waxes, sclerotized and unsclerotized proteins, and other materials.
dactyl the median claw at the ventrodistal tip of the telotarsus of the leg.  The dactyl is smaller than the ungues (tarsal claws).
dentate margin (see primary denticle row).
enlarged primary row denticle a larger denticle found at the proximal end of a primary denticle subrow; the enlarged primary row denticles are situated within the denticle row and serve to divide the denticle row into distinct subrows.
femur the third leg or pedipalpal segment from the base.  The femur is the first long segment.  On the pedipalp, the femur bears trichobothria, setae, and carinae of taxonomic importance.
fixed finger the immovable digit of the chelicera or pedipalp chela.  The cheliceral fixed finger bears a basal bicusp, a subdistal tooth, and a distal tooth; on its underside is a weak to moderate longitudinal carina which may bear denticles or crenulations.  The fixed finger of the pedipalp chela bears trichobothria and a variety of setae; in addition it bears the primary denticle row, which forms its cutting edge (or dentate margin) with the movable finger.
genital opercula a pair of small flaps that cover the genital pore, the two together forming an oval structure.
genital papillae small fingerlike projections that are associated with the membrane of the genital pore of the male scorpion and protrude from beneath the distal margins of the genital opercula.
genital pore the genital opening concealed by the genital opercula.
hemispermatophore one of a pair of formative internal male reproductive structures, secreted by the paraxial organ.  During courtship, the two hemispermatophores are cemented together to form the spermatophore, which carries a sperm packet and is deposited on the substrate.
inner accessory denticles denticles flanking the primary denticle row of the chela fingers, usually more or less paired with an enlarged primary row denticle.
interocular triangle the area on the carapacial surface lying between the median and lateral eyes.
intersegmental membrane soft cuticle between adjacent tergites or sternites on the mesosoma.
keels (see carinae).
lateral eyes the paired cluster of small eyes at the anterolateral corners of the carapace.  In vaejovids, there are typically three pairs of lateral eyes, although aberrations and exceptions exist (for example, the troglophilic Uroctonites sequoia often bears two pair of lateral eyes instead of three).
manus the palm of the chelicera or of the pedipalp chela.  Attached distally to the palm are the fixed and movable fingers of these two chelate appendages.
median claw (see dactyl).
median eyes the pair of larger eyes situated middorsally on the carapace.
mesosoma the "body" of the scorpion, comprising the first seven of the opisthosomal (abdominal) segments.  A given mesosomal segment is provided dorsally with a tergite and ventrally with the genital opercula (1st mesosomal segment), pectines (2nd mesosomal segment), or sternite (segments III-VII).  The tergites and sternites are joined together by softer cuticle called intersegmental membranes; the tergites and sternites are connected by similar soft cuticle referred to as the pleural membrane.
metasoma the "tail" of athe scorpion, consisting of five tubular segments.  The metasoma is actually part of the opisthosoma (abdomen), rather than an actual tail.  The metasomal segments bear longitudinal carinae, whose strength and granulation provide useful taxonomic characters.  Ventrodistally, in a membranous area, on the fifth metasomal segment is the anus.
movable finger the movable digit of the chelicera or of the pedipalp chela.  On the chelicera, the movable finger bears a dorsal series of teeth and a ventral carina (the ventral carina may bear crenulations or denticles); ventrodistally on the movable finger may be a serrated comb-like structure called the serrula.  On the pedipalp, the movable finger (considered to be the tarsus of the pedipalp) bears a series of denticles along its cutting margin, as for the fixed finger.  The movable fingers attach to their respective appendages by an articular membrane.
opisthosoma the abdomen of the scorpion, consisting of seven mesosomal and five metasomal segments.  The opisthosoma also bears the genital pore and opercula (1st segment), the pectines (2nd segment), and four pairs of book lung openings on the sternites.
ovariuterus a reticulate internal network of reproductive tubules in the female scorpion.  In vaejovids, the oocytes develop in association with the ovariuterus and move to the interior for fertilization and embryonic development.
palm the thickened basal portion of the pedipalp chela from which the fixed finger arises and the movable finger articulates.  The palm bears a number of carinae (keels), whose strength and granulation provide good taxonomic characters.
patella on the pedipalp, the second long segment from the base.
pectines large, comblike sensory structures found ventrally on the second mesosomal segment.  The pecten is a soft, flexible structure made of the following components:  an anterior series of marginal lamella, a series of median lamella, a series of small circular fulcra, and a series of elongated pectinal teeth oriented at right angles to the marginal and median lamellae.  The pectinal teeth bear sensorial areas whose senilla provide for both mechanoreception (evaluation substrates) and chemoreception (pheromone detection).  The pectinal tooth count is of taxonomic importance.
pedal spurs two small spur-like structures situated in the ventrodistal articular membrane of the leg between the basitarsus and telotarsus.
pedipalps the second pair of appendages on the scorpions prosoma, consisting of the coxa, trochanter, femur, patella, chela manus, fixed finger, and movable finger (the chela manus and fixed finger are considered the tibia, and the movable finger the tarsus).
pleural membrane soft cuticle on the lateral aspects of the mesosoma between the tergites and sternites.
pre-oral chamber a small chamber anterior to the mouth surrounded ventrally by the coxal endites (of legs I and II), laterally by the pedipalpal coxae, and dorsally by the chelicerae.  As a prey item is masticated by the chelicerae, digestive enzymes are regurgitated into the chamber to begin digestion of the food.  The walls of the pre-oral chamber are supplied with a dense array of fine setae that serve as a filter to keep larger particles from entering the mouth.
primary denticle row the row of denticles found on the cutting margins of the pedipalp
prosoma the anterior of the two main body regions of a scorpion, serving as a combined head and thorax.  The prosoma bears the carapace dorsally and the coxosternal region ventrally; the chelicerae, pedipalps, and four pairs of legs are associated with the prosoma.
scalloping in reference to the lateral aspect of the pedipalp chela fingers, when the margins of one or more of the denticle rows are concave (rather than straight).  Scalloping of the basal denticle row of the fixed finger often corresponds to the development of a lobe on the movable finger.
serrula a cuticular comb-like structure found ventrodistally on the cheliceral movable finger of many vaejovids.
seta a socketed, chitinous hair or bristle found on the body and appendages of scorpions.  Setae vary considerably in thickness, shape, and length.  Most are innervated and serve as tactile receptors or chemoreceptors.
setal comb a linear array of bristles associated with the basitarsus (and sometimes the telotarsus) of the legs, in particular legs I-III.  Setal combs are characteristic of psammophilic (sand dwelling) scorpions; among the vaejovids, setal combs are well developed in Paruroctonus (most species), Paravaejovis, Smeringurus, and Vejovoidus.  A few species of Vaejovis have setal combs, but development is not as great as in the paruroctines.
spermatophore the male reproductive structure, formed during courtship from two internal hemispermatophores (see hemispermatophore for more information).
spinules smaller, spine-like projections of the cuticle (not socketed setae) which are located on the basitarsi and tarsi of the legs.
spiracles the external openings, located on the ventrolateral corners of sternites III-VI, into the book lungs of the scorpion.
sternites ventral plates associated with the mesosoma.
sternum a small median plate on the underside of the prosoma lying between the coxae of the legs.  In vaejovids, the sternum is always pentagonally shaped.
subaculear tubercle (or tooth) a cuticular prominence located on the ventrodistal portion of the vesicle, where the aculeus joins.
tarsal claws (see ungues).
tarsus the distalmost segment of the leg, including the basitarsus and telotarsus.  Also, the movable finger of the pedipalp.
telotarsus the distal portion of the tarsus, to which are attached the ungues (tarsal claws) and dactyl.
telson the stinger apparatus of the scorpion, consisting of a bulb-shaped vesicle and curved aculeus.
tergite dorsal plates associated with the mesosoma.
tibia the fourth segment of the leg from the base.  Also, the chela manus + fixed finger of the pedipalp.
trichobothrium a thin, willowy sensory seta arising from a (usually) large, circular socket on the surface of the pedipalpal cuticle.  The trichobothrium is a highly sensitive hair that is easily moved by air-borne vibrations, allowing it to be used to detect aerial prey, such as moths.  Trichobothria are located only on the pedipalpal femur, patella, and tibia (chela palm + fixed finger).
trochanter the second segment of the pedipalp or leg.  On the leg, the trochanter is a short cylindrical segment.
ungues the curved, paired claws located at the distal end of the telotarsus.  Ventrally, between the two claws is the smaller, triangular dactyl.
vesicle the bulb-shaped portion of the telson which gives rise distally to the aculeus.  Internally, the vesicle contains the paired venom glands that are surrounded my musculature to squeeze the venom into the aculear duct.

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