Definition of prosoma in US English:



  • another term for cephalothorax
    • ‘The upper or dorsal side of the prosoma is equipped with two prominent kidney-shaped compound eyes, and in the middle a pair of small ocelli or simple eye-like sense-organs.’
    • ‘Similarly, in spiders there is a common posterior boundary for five of the anteriorly expressed Hox genes coinciding with the division between the two body tagma, the prosoma and opisthosoma.’
    • ‘Chelicerates are characterized by a pair of chelate preoral appendages and a body divided into two tagmata, the prosoma and opisthosoma.’
    • ‘The chelicerate body plan is characterized by two tagmata, the prosoma, including head structures, and the opisthosoma.’
    • ‘Cheliceramorphs are distinguished by having a body divided into two main divisions, technically called the prosoma and the opisthosoma.’


Late 19th century: from pro- ‘before’ + Greek sōma ‘body’.