Cephalothorax

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cephalothorax

[¦sef·ə·lə′thȯr‚aks]
(invertebrate zoology)
The body division comprising the united head and thorax of arachnids and higher crustaceans.

Cephalothorax

 

that part of the body of arthropods formed as a result of the fusion of the cephalic and thoracic segments.

The cephalothorax is characteristic of higher crustaceans and chelicerate arthropods (Arachnida, Xiphosura, and the extinct paleozoic Eurypteridae). Among the crustaceans, the cephalothorax is formed in Decapoda by the fusion of six cephalic and seven thoracic segments. In Chelicerata it consists of the six front segments of the body (which usually bear the appendages), to which a seventh (pregenital) segment is sometimes attached.

References in periodicals archive ?
hospitalis Fraser, 1920 by having in the female a genital complex that is at least half the length of the cephalothoracic shield (including frontal plates) and with small, rounded posterolateral lobes, a 1-segmented abdomen that is less than one-quarter the length of the genital complex, a maxillule with two large tines on the dentiform process, a maxilliped without a myxal process, a pair of non-bifid tines on the sternal furca, the spine on the first exopodal segment of leg 3 inserted distally on the basal swelling, a 3-segmented leg 4 exopod, and the inner lobe of leg 5 not protruding beyond the posterior margin of the genital complex.
The hepatopancreas is a large, yellowish-brown, compact organ, which occupies much of the cephalothoracic cavity, posterior to the cardiac portion of the stomach.
The frequency of FPs with stage 4 ovaries (ovary completely filling the available cephalothoracic space) increased dramatically in FPs incubating stages 3-4 embryos (Fig.
Later, we established the relationship existing between the number of eggs and the cephalothoracic length of the carrying females (Arana & Tiffou, 1970; Arana et al.
Male (holotype): Prosoma whitish without a clearly marked fovea and practically indistinguishable cephalothoracic junction.
Cephalothoracic sulci in linyphiine spiders (Araneae, Linyphiidae, Linyphiinae).
In decapods, the hepatopancreas is a bilobed brown and yellowish organ that occupies much of the cephalothoracic cavity.
Both groups belong to the widely-known, tetrafamilial 'archaeid assemblage', sharing with the Afrotropical, Malagasy and Australian Archaeidae and the New Zealand and Chilean Mecysmaucheniidae an anterior cephalothoracic foramen completely surrounding the cheliceral bases (Forster & Platnick 1984).
Parturial FPs near the prespawning molt were identified by gonad condition (vitellogenic oocytes filling the cephalothoracic space behind the eyes and above the cardiac stomach) and developmental state of brooded embryos (near hatching, with large eyes and little or no yolk).
Large specimens of the Atlantic shore crab (Carcinus maenas with a cephalothoracic shield exceeding 5 cm in width, were obtained from a local distributor.