Insertion and withdrawal of extremely elongated genitalia: a simple mechanism with a highly modified morphology in the leaf beetle, Lema coronata

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Complicated genital structures are widely known in many animals. It is assumed that an increasing morphological complexity of genital structures would also increase the difficulty of inserting and withdrawing the structures. We examined the insertion and withdrawal mechanisms of extremely elongated genitalia in the Japanese leaf beetle, Lema (Lema) coronata. Insertion and withdrawal processes are completed quickly. Investigation of genital morphology showed that there are no protractor or retractor muscles attached to the elongated part. Instead, the elongated part is tightly enveloped by a membrane. Because of the close fit between the elongated part and its surrounding membrane, eversion of the membrane allows for insertion of the elongated part, and retraction of the membrane induces withdrawal of the elongated part. This surrounding membrane makes it possible to store the median ejaculatory guide (MEG) in a small genital cavity, with the basal portion of the elongated part extending internally against the entrance. This unusual character state is observed only in members of the subgenus Lema, which also have the elongated part. This condition can be considered to be a preadaptation for extreme elongation of genitalia.

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詳細情報

  • CRID
    1050001339005728256
  • NII論文ID
    120002834668
  • NII書誌ID
    AA00565321
  • HANDLE
    2115/44962
  • ISSN
    00244066
  • 本文言語コード
    en
  • 資料種別
    journal article
  • データソース種別
    • IRDB
    • CiNii Articles

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