External genitalia of the Psocodea, with particular reference to lice (Phthiraptera)

In all Phthiraptera the female genital opening is posterior to sternum IX. The 'copulatory valve' of sternum VIII in female Phthiraptera is homologous with the psocopteran gonapophysis VIII, and the "copulatory valve" of sternum IX + X of female Boopidae with the psocopteran paraproct. The 'copulatory valve' of female sternum IX + X in other Phthiraptera remains of uncertain homology. The 'genital sternite' of female Boopidae is homologous with the psocopteran gonangulum, and the 'posgenital sternite' with sternite IX + X. Homology of sternites in this region is uncertain for other Phthiraptera. The male external genitalia of the Psocodea comprise (in ground plan) a basal apodeme supporting caudially a pair of mesomeres which may fuse dorsally and a pair of parameres which may fuse ventrally. The endophallus everts between these phallomeres and is fused to their inner faces. The morphology of the male genetalia in Psocodea contrasts with that in Thysanoptera, where an aedeagus (sensu Snodgrass) is present.