Spermathecae

Our understanding of the functional anatomy of the female cockroach reproductive tract in relation to cryptic mate choice languishes behind that of some other insect groups. The shape, number, elasticity, duct length, coiling pattern, musculature, presence of valves or sphincters, and chemical milieu of spermathecae play a strong role in sperm selection by females (Eberhard, 1996). Multiple sperm storage sites are particularly important in allowing females to cache and use the ejaculates of different males selectively (Ward, 1993; Hellriegel and Ward, 1998). Sperm storage organs in cockroaches have not received much consideration since McKittrick (1964), who demonstrated a great deal of variety in the form, number, and arrangement of spermathecae (Fig. 6.15). In Crypto-cercus the spermatheca is forked, with the branches terminally expanded; the single spermathecal opening lies in the roof of the genital chamber. The spermatheca of Lamproblatta has a wide, sclerotized basal portion and a slender forked distal region. Within the Polyphagidae, Arenivaga has a single, unbranched spermatheca, but Polyphaga has a small tubular branch coming off about halfway up the main duct. In the Blattellidae the sper-mathecal opening is shifted to a more anterior position on the roof of the genital chamber, far in advance of the base of the ovipositor. Some species of Anaplecta have, in addition, a pair of secondary spermathecae that open separately on the tip of a small membranous bulge, the genital papilla, that lies at the anterior end of the floor of the genital chamber (Fig. 6.15F). The cockroaches of this genus thus have either one or three spermathecae. The Pseudophyllodromiinae, Blattellinae, Ectobiinae, Nycti-borinae, and Blaberidae have secondary spermathecae only. The spermathecal pores in these may be widely spaced (Fig 6.15G—Pseudophyllodromiinae except Su-pella) or more closely situated within a spermathecal groove (Fig 6.15H—Supella, Pseudomops), thought by Snodgrass (1937) to function as a sperm conduit. One pair of spermathecae, each with a separate opening, is typically present in Pseudophyllodromiinae, but the Blattellinae may have two (Fig. 6.15I) or more pairs, each with a separate opening. Xestoblatta festae averages 10 or 11 spermathecal branches, but these converge into just two exterior openings (Fig. 6.16K). Nyctibora sp. (Fig. 6.15J) and Paratropes mexicana have three pairs of spermathecae. All Blaberidae have a single pair of spermathecae that open on the genital papilla or directly into the common oviduct; in most species they are accompanied by a conspicuous pair of spermathecal glands (McKittrick, 1964).

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