Spermatophore Transfer and Ejection in the Beetle

Spennatophore transfer in the beetle Pseudoxychila tarsa/i.s occurred in a-isociation with one of the four movements of the body and aedeagus that males performed during copulation. Some copulations did not result in spermatophore transfer, and females ejected some of the spermatophores they received. This suggests females may be capable of exerting cryptic female choice. Data on spermatophore transfer do not fit with a previous hypothesis regarding the "phases" of P. tarsalis copulation. Matings of tiger beetles (Coleoptera: Cicindelidae) have been described as consisting of three phases: an initial intromission in which the flagellum (a sclerite of the male aedeagus) prepares the duct of the female spermatheca for sperm transfer, followed by retraction of the aedeagus, and another intromission in which semen transfer occurs, usually in a spermatophore (Freitag et al., 1980). This was based on three kinds of evidence: that the flagellum of tiger beetles does not connect with the ejaculatory pore, that the shape of the flagellum matches that of the spermathecal duct, and three behavioral phases of mating described for Pseudoxychila tarsalis Bates (Palmer, 1976) and five Cicindela species (Freitag et al., 1980). Palmer's (1976) description of the mating behavior of P. tarsalis was incomplete (Rodriguez, 1998). Instead of three phases, copulations had 1-20 intromissions in which the male performed up to four different movements with his body and aedeagus: prying, thrusts, small thrusts, and pulling. Prying lasted several seconds and consisted of a deep penetration of the aedeagus into the female and a change in its inclination; thrusts were short pushes of the aedeagus into the female; small thrusts were vibrations at the base of the aedeagus; and in pulling the male partially retracted the aedeagus. Between intromissions, the male courted the female by rubbing her body with his middle legs. There was geographic variation in P. tarsalis male copulatory behavior, and stronger differences in comparison to P. bipustulata, suggesting sexual selection on male courtship behavior. The female often struggled before and during copulation, and sometimes ejected one or two spermatophores during or after copulation. The present paper analyzes the copulatory movements of P. tarsalis males in relation to spermatophore transfer, presenting observations on spermatophore ejection, the organization of sperm within the spermatheca, and measurements of the male flagellum and the female spermathecal duct. The data of spermatophore transfer and ejection suggest female P. tarsalis may be capable of cryptic female choice, in accordance with the hypothesis that male copulatory courtship behavior evolves by sexual selection (Eberhard, 1994, 1996). ' Current address: Department of Entomology, University of Kansas, Lawrence, KS 66045, USA. Accepted for publication 10 June 1998. JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY