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The anterior of the two or three main divisions of the body of certain invertebrates, especially the cephalothorax of an arachnid.

[pro- + Greek sōma, body; see teuə- in Indo-European roots.]

pro·so′mal adj.


n, pl -mas or -mata (-mətə)
(Zoology) zoology the head and thorax of an arachnid


(proʊˈsoʊ mə)

n., pl. -mas, -ma•ta (-mə tə)
an anterior body region, esp. the arthropod cephalothorax.
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References in periodicals archive ?
The arthrodial membrane between the prosoma and the opisthosoma of each horseshoe crab was exposed, and the hinge joint was sterilized with 70% ethanol.
Before the trial, we anesthetized the male and female with C[O.sub.2] and measured them for body mass (to 0.0001 g) and prosoma width (to 0.01 mm).
The study contains a detailed description of a larva of the Eratigena atrica spider, which had a well-developed prosoma and an additional, partly developed head with two segmented pedipalps and one chelicera with two fangs.
CUADRO 1 Caracteres morfologicos empleados para el analisis cladistico TABLE 1 Morphological caracteres used for the cladistic analyses Caracteres Estados de caracter Prosoma 1.
La arana presento un largo total de aproximadamente 1 cm (borde anterior del prosoma al borde posterior del opistosoma) en tanto que los colibries aproximadamente 4 cm de la punta del pico a la punta de la cola.
4ag), with prosoma, abdomen and legs with a reticulated brown pattern of coloration, but without any difference in the reproductive characters, so here they are considered as be part of the same species.
Abbreviations: ALE--anterior lateral eyes; AME--anterior median eyes; AW anterior width of dorsal shield of prosoma; d--dorsal; DK--serial field number of material collected by Dirk Kunz; OL--opisthosoma length; OW--opisthosoma width; p--prolateral; PJ--serial number for Sparassidae examined by Peter Jager; PL--prosoma length; PLE-posterior lateral eyes; PME--posterior median eyes; PW--prosoma width; r--retrolateral; RTA-retrolateral tibial apophysis; SD-serial number of Sparassidae with tissue/DNA samples available; v-ventral; I-IV-referring to leg numbers.
All chelicerates other than the Pycnogonida have an Entosternite within the prosoma cavity to which the leg muscles are attached [9].
La arana habia sido capturada por la parte anterior del prosoma y el lagarto se mantenia en posicion vertical, con la cabeza hacia abajo (figura 1).
Female total length: 4.80, prosoma length 2.10, prosoma width 1.80, opisthosoma length 2.70, opisthosoma width 2.0.
The CT datasets were transferred either to Prosoma or ONCENTRA Virtual simulation and contouring system through the DICOM network.
El cuerpo de la hembra es ovalado con prosoma prominente, segmentos prepigidiales con lobulos laterales bien desarrollados; pigidio con lobulos medios bien visibles y divergentes y poros perivulvares numerosos y bien desarrollados.