Mate Holding Devices

Some male genital structures function as mate-holding devices, allowing him to stay physically attached to the female during copulation. If the female mounts the male prior to genitalic connection (type I mating behavior), the male has a greatly extensible, sclerotized hook ("titil-lator"), used to seize and pull down her crescentic sclerite and to maintain his grasp on her when she rotates off his back into the opposed position. After the pair is end to end the male inserts the genital phallomeres. In B. germanica a pair of lateral sclerites, the paraprocts, grip the ovipositor valves from each side, and parts of the right phallomere (cleft sclerite) hold the valves from the ventral side (Fig. 6.12). The location of the genital hook in cockroach males varies, and distinguishes the Pseudo-phyllodromiinae (hook on right—Fig. 6.11A) from the Blattellinae (hook on left—Fig. 6.11C). The hook is always on the right in the Blaberidae (Fig. 6.11D) (Roth, 2003c).

Besides maintaining his grasp during positional changes, there are two basic reasons why a male needs a secure connection to the female during copulation: male competition and female mobility. In several species of

Fig. 6.11 Examples of variation in male genitalia. (A) Genitalia (dorsal) of Allacta australiensis (Blattellidae: Pseudophyllodromiinae). Accessory median phallomere is broad, with an apical brush-like modification (arrow). From Roth (1991d). (B) Subgenital plate and genitalia (dorsal) of Hemithyrsocera nathani (Blattellidae: Blattellinae). A huge, sclerotized, densely setose brushlike structure is found on the left side (arrow). From Roth (1995a). (C) Subgenital plate and genitalia (dorsal) of Parasigmoidella atypicalis (Blattellidae: Blattellinae). Note distally curved median phallomere with a pick-axe-like apex (arrow) and three-fingered "claw" on right. From Roth (1999b). (D) Highly reduced phallomeres on the extruded aedeagal membrane of Panesthia cribrata (Blaberidae: Panesthiine). From Walker and Rose (1998). Phallomeres are labeled according to McKittrick's (1964) classification. (E) Extraordinarily complex genitalia (dorsal) of Homopteroidea nigra (Polyphagidae). From Roth (1995d).

Fig. 6.11 Examples of variation in male genitalia. (A) Genitalia (dorsal) of Allacta australiensis (Blattellidae: Pseudophyllodromiinae). Accessory median phallomere is broad, with an apical brush-like modification (arrow). From Roth (1991d). (B) Subgenital plate and genitalia (dorsal) of Hemithyrsocera nathani (Blattellidae: Blattellinae). A huge, sclerotized, densely setose brushlike structure is found on the left side (arrow). From Roth (1995a). (C) Subgenital plate and genitalia (dorsal) of Parasigmoidella atypicalis (Blattellidae: Blattellinae). Note distally curved median phallomere with a pick-axe-like apex (arrow) and three-fingered "claw" on right. From Roth (1999b). (D) Highly reduced phallomeres on the extruded aedeagal membrane of Panesthia cribrata (Blaberidae: Panesthiine). From Walker and Rose (1998). Phallomeres are labeled according to McKittrick's (1964) classification. (E) Extraordinarily complex genitalia (dorsal) of Homopteroidea nigra (Polyphagidae). From Roth (1995d).

blaberids, rivals disturb or attack courting or mating males. Copulations may be broken off because of interference in N. cinerea (Ewing, 1972). In B. craniifer males assault copulating pairs by jumping on their backs and attacking their point of juncture. The interference may cause separation of the pair, but only if it occurs during the first few seconds after they assume the opposed position. The copulating male "shows no reluctance in fighting with the intruder," and "the trio may careen about the mating chamber" (Wendelken and Barth, 1985,1987). A tight grasp of the female is also required because the pair may travel during copulation. Pairs are usually quiescent unless disturbed, in which case they move away. It is invariably the female that is responsible for the locomotion, dragging the passive male along in her wake (Roth and Barth, 1967). She can move with astonishing speed, pulling the "furiously backpedaling" male behind her (Simon and Barth, 1977a). Blattella germanica (Roth and Willis, 1952a), Byr. fumigata (Barth, 1964), Ell. humerale

(= affine) (Pope, 1953), Latiblattella spp. (Willis, 1970), Parcoblatta fulvescens (Wendelken and Barth, 1971), and P. americana (Simon and Barth, 1977a) are among the species in which this behavior has been reported. It also occurs in G. portentosa, even though the male is much heavier than the female (Barth, 1968c).

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