The unfortunate couple were embarrassed beyond all mortification, not simply for having been surprised in the act by the minister, but also for their inability to separate, to unclasp, to unlink, to undo all the various latches, clamps and sphincters that linked them together, tail to tail in opposite directions.
— D. Harington, The Cockroaches of Stay More
The genitalia of male cockroaches are frequently used as an example of the extreme complexity that may evolve in insect reproductive structures (e.g., Gwynne, 1998). They have been likened to Swiss army knives in that a series of often-hinged hooks, tongs, spikes, and other lethal-looking paraphernalia are sequentially unfolded during copulation. Marvelous though all that hardware may be, it has not yet inspired research on its functional significance. Seventy years ago Snodgrass (1937) stated that "we have no exact information on the interrelated functions of the genital organs" of cockroaches, and the situation has improved only slightly since that time. While there is a vast literature on pheromonal communication, reproductive physiology, male competition, and behavioral aspects of courtship in cockroaches, we know surprisingly little about the "nuts and bolts" of the copulatory performance, and in particular, how the male and female genitalia interact.
Here we briefly describe cockroach mating systems, and the basics of mate finding, courtship, and copulation. We then focus on just a few topics that are, in the main, relevant to the evolution of cockroach genitalia. We make no attempt to be comprehensive. Our emphasis is on male and female morphological structures whose descriptions are often tucked away in the literature on cockroach systematics and are strongly suggestive of sperm competition, cryptic mate choice, and conflicts of reproductive interest. One goal is to shift some limelight to the female cockroach, whose role in mating dynamics is poorly understood yet whose morphology and behavior suggest sophisticated control over copulation, sperm storage, and sperm use.
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