Two intromittent organs in Zorotypus caudelli (Insecta,Zoraptera): the paradoxical coexistence of an extremely long tube and a large spermatophore |
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Authors: | Yoko Matsumura Kazunori Yoshizawa Ryuichiro Machida Yuta Mashimo Romano Dallai Marco Gottardo Thomas Kleinteich Jan Michels Stanislav N. Gorb Rolf G. Beutel |
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Affiliation: | 1. Entomology Group, Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich‐Schiller‐Universit?t Jena, , D‐07743 Jena, Germany;2. Laboratory of Systematic Entomology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, , Sapporo, 060‐8589 Japan;3. Sugadaira Montane Research Center, University of Tsukuba, , Nagano, 386‐2204 Japan;4. Department of Life Sciences, , I‐53100 Siena, Italy;5. Department of Functional Morphology and Biomechanics, Institute of Zoology, Christian‐Albrechts‐Universit?t zu Kiel, , D‐24118 Kiel, Germany |
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Abstract: | Very unusual genitalia of the species Zorotypus caudelli are described. It contains the unique configuration of two different intromittent organs, one of them strongly elongated. Hyper elongated genitalia are known in different groups of insects. Males have to accommodate these unwieldy structures in the limited spaces of the abdomen and manipulate them acutely during copulation. A crucial question is how do species with elongated genitalia cope with these requirements? To investigate this, we studied key features enabling storage, insertion, and withdrawal of the elongated genitalia. The co‐existence of an elongated narrow tube and a bulky spermatophore is a highly unusual and apparently paradoxical condition. However, we demonstrate that the tube is not involved in sperm transmission, whereas the large spermatophore is transferred to females by a membranous fold of the genitalia. The movement of the spermatophore is caused by haemolymph pressure, which likely also promotes the insertion of both intromittent organs. A comparison with the genital anatomy and reproductive mode in related groups suggests that the elongated tube and its accommodating pouch is a de novo structure, and that the ancestral sperm transport via spermatophore is a preadaptive condition for the acquisition of this unusual structure. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 40–54. |
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Keywords: | copulation insertion novelty penis preadaptation sexual selection withdrawal |
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