Contributions to Zoology, 86 (3) – 2017Xin Tong; Lu Jiang; Bao-Zhen Hua: A unique mating pattern of Panorpodes kuandianensis (Mecoptera: Panorpodidae)
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Torsion of the female abdomen

The abdominal segments of female P. kuandianensis are unique in that the abdominal segments VII and VIII (A7 and A8) and the most part of A9 are usually concealed within abdominal segment VI (A6). In the process of position-change, the terminal abdomen of the female undergoes a rotation clockwise or anticlockwise (Figs 5c, d). The abdominal segments are recurved upward when the paired male and female sustain a V-shape mating position. When the mating position changes to end-to-end, A7 of the female is twisted a very small angle, A8 is twisted ~60° (Figs 4, 5c, b) and A9 is twisted ~120° (Figs 4, 5d). The torsion of the female abdomen results from the deformation of the intersegmental membrane.

FIG2

Fig. 5. Coupling genitalia and torsion of the female abdomen. a, coupling genitalia in lateral view; b, the same, with the hypandrium removed to show the cerci of the female and the basal process of the male; c, the torsion of the female abdominal segments VII−VIII, lateral view, with the epandrium removed to show the subgenital plate of the female and the basal tooth of the male; d, the torsion of the female abdominal segments VII−IX, lateral view. BP, basal process; BT, basal tooth; Ce, cercus; Ep, epandrium; Gc, gonocoxite; Gs, gonostylus; Hv, hypovalve; Pm, paramere; SP, subgenital plate; S6, sternum VI; T6−T9, tergum VI−IX.