Ultrastructure of spermatozoa of orsolobidae (Haplogynae, Araneae) with implications on the evolution of sperm transfer forms in Dysderoidea

Authors

  • Elisabeth Lipke,

    Corresponding author
    1. Zoological Institute and Museum, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany
    • Correspondence to: Elisabeth Lipke; General Zoology and Zoological Systematics, Zoological Institute and Museum, Ernst-Moritz-Arndt University of Greifswald, Anklamer Str. 20, D-17489 Greifswald, Germany. E-mail: ELipke@gmx.de

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  • Martín J. Ramírez,

    1. Research Scientist, Division of Arachnology, Museo Argentino de Ciencias Naturales—CONICET, Buenos, Aires, Argentina
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  • Peter Michalik

    1. Zoological Institute and Museum, Ernst-Moritz-Arndt University of Greifswald, Greifswald, Germany
    2. Research Associate, Division of Invertebrate Zoology, American Museum of Natural History, New York
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ABSTRACT

Haplogynae are highly diverse with respect to the primary male genital system and sperm characteristics. Additionally, all sperm transfer forms (STF) known for spiders are present. Besides individually transferred sperm (cleistospermia), sperm are transferred as conjugates, both primary (synspermia) and secondary sperm conjugates (coenospermia, rouleaux) occur. Nevertheless, the ultrastructure of spermatozoa and STF are described for few Haplogynae and often only one representative species was studied, resulting in a superficial insight in the evolution of these traits. To elucidate the evolution of STF within Haplogynae we investigated representatives of four genera of the dysderoid family Orsolobidae. Our data show the presence of synspermia (Orsolobus, Osornolobus, Hickmanolobus, and Tasmanoonops) and also cleistospermia (Osornolobus). The occurrence of different STF within one family or even genus has not been described for any other spider taxon so far. Moreover, the synspermia of species of Tasmanoonops and Hickmanolobus were not covered by a secretion sheath suggesting a previously unknown strategy of transferring sperm that is possibly related to sperm residency time or female triggered processes after copulation. Based on serial ultrathin sectioning and subsequent 3D-reconstruction, we obtained detailed measurements revealing remarkable size differences of STF. To evaluate the previously suggested correlation with the most distal region of the spermophor inside the embolus (intromittent part of the copulatory organ) we measured the diameter of the spermophor using micro-computed X-ray tomography data to obtain corresponding morphometric parameters. Based on these data only two species show similarity in STF and spermophor diameter. J. Morphol. 275:1238–1257, 2014. © 2014 Wiley Periodicals, Inc.

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