Insect of the week – number 38


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3 Responses to “Insect of the week – number 38”

  1. Dave says:

    shouldn’t that be the “bifurcated posteromedian process of the mesonotum-propodeum complex (why not mesosoma?)”? thanks.

  2. ardeans says:

    Referring to the location of this process as part of the propodeum-metanotum complex is more precise, as the propodeum-metanotum complex is part of the mesosoma. At least that’s my interpretation.

  3. Miko says:

    Great question! Ceraphronoidea is a really interesting Hymenoptera superfamily concerning the fusion of different mesosomal sclerites. The metanotum (as i know) is always separated from the first abdominal tergum (propodeum), whereas the metapleuron is fused to the first abdominal tergum (propodeum) in apocritan wasps. In Ceraphronoidea, however, even the metanotum is fused with the first abdominal tergum (propodeum). Although the line of fusion is perhaps marked by a transverse sulcus extending along the anterior margin of the fused metanotum and propodeum present only in some Dendrocerus species, we can not define the border between the two originally separated sclerites. The only thing we can be sure is that anything located posteriorly of the antecostal sulcus and antecosta (metaphragma) of the propodeum is propodeal and not metanotal in origin. If two or more sclerites are fused, and we can not define the suture between the two ancestral sclerites, we often use the term “complex”. In some parasitic Hymenoptera the metanotum possess medially a spine (usually corresponding with the metascutellum (dorsellum) and called metanotal or dorsellar or metascutellar spine), however, in some other Apocrita, the propodeum possess an anteromedian process (anteromedian propodeal process or spine). In numerous Ceraphronoidea taxa there is a spine located on the anterior margin of the fused metanotum and anterior propodeum (in Pteroceraphron this process is bifurcated). The site of origin of the process sometimes reaches the anterior margin of the complex
    therefore metanotal in origin, however the posterior margin of the process extends posteriorly of the antecostal sulcus of the propodeum (first abdominal tergum), therefore propodeal in origin. It would be awesome to homologize the process of Ceraphronoidea either with the metanotal or with the propodeal process of other Hymenoptera, but since we can not define the origin of the process we can not homologize this structure. Therefore we should not use either of the formerly proposed terms and instead we are talking here about the process of the metanotum-propodeum complex.
    So
    1. in the blog there is no mesonotum-propodeum but metanotum-propodeum complex, even in Ceraphronoidea mesonotum is separated from any propodeal or metanotal structures (again, metanotum propodeum complex used for the fused metanotum and propodeum).
    2. even if we would use the term mesonotum-propodeum complex, it would not be equivalent with the mesosoma, since the mesosoma IS_A(n) anatomical cluster composed of the prothorax, mesothorax, metathorax and the first abdominal tergum (propodeum). Therefore mesonotum-propodeum complex is only the part of the mesosoma.
    Dave! I am really happy, that you have sent this comment and let us to tell more about ceraphs and hym morphology!

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