Sex-specific elaborations are common in animals and have attracted the attention of many biologists, including Darwin [1]. It is accepted that sexual selection promotes the evolution of sex-specific elaborations. Due to the faster replenishment rate of gametes, males generally have higher potential reproductive and optimal mating rates than females. Therefore, sexual selection acts strongly on males [2], leading to the rapid evolution and diversification of male genitalia [3]. Male genitalia are sometimes used as devices for coercive holding of females as a result of sexual conflict over mating [4, 5]. In contrast, female genitalia are usually simple. Here we report the reversal of intromittent organs in the insect genus Neotrogla (Psocodea: Prionoglarididae) from Brazilian caves. Females have a highly elaborate, penis-like structure, the gynosome, while males lack an intromittent organ. The gynosome has species-specific elaborations, such as numerous spines that fit species-specific pouches in the simple male genital chamber. During prolonged copulation (~40-70 hr), a large and potentially nutritious ejaculate is transferred from the male via the gynosome. The correlated genital evolution in Neotrogla is probably driven by reversed sexual selection with females competing for seminal gifts. Nothing similar is known among sex-role reversed animals.

A new genus of Sensitibillini from Brazilian caves (Psocodea: Tsocoptera': Prionoglarididae). -The genus Neotrogla Lienhard gen. n. is described for three new cave-dwelling species from Brazil: Neotrogla brasiliensis Lienhard sp. n. (from Minas Gérais State), N. aurora Lienhard sp. n. (from Tocantins State) and N. truncata Lienhard sp. n. (from Bahia State). Thèse species are the first Neotropical représentatives of the subfamily Speleketorinae and the first New World représentatives of the tribe Sensitibillini, previously known only from southern Africa. This distributional pattern of Sensitibillini is tentatively interpreted as due to WesternGondwanan vicariance. In the females of Neotrogla a complex of accessory structures to the spermathecal duct is described and denoted by the new term "gynosome". A hypothesis of functional complementarity, during copulation, between the "penis-like" gynosome and the strongly reduced maie phallosome of Neotrogla is presented.

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Siamoglaris zebrina gen. n., sp. n., the first representative of Prionoglarididae from the Orientai Region (Insecta: Psocoptera). -Siamoglaris zebrina gen. n., sp. n. is described and illustrated from a male specimen collected in Thailand. The new genus is closely related to the Palaearctic genus Prionoglaris Enderlein. Illustrations of the type species of that genus, P. stygia Enderlein, are also given. The systematic position of these two genera within the family Prionoglarididae is discussed and the family is subdivided into two subfamilies: Prionoglaridinae Badonnel and Speleketorinae Smithers. A key to the adults of the genera of the family Prionoglarididae is provided.

The cave-dwelling psocid tribe Sensitibillini ( Afrotrogla , Neotrogla and Sensitibilla ) is of special morphological and evolutionary interest because of its possession of reversed copulatory organs: i.e. females of Afrotrogla and Neotrogla have a penis-like organ. The female penis structure is highly variable among taxa, as is the case of the male penis in animals with normal copulatory organs. Here, we present the first molecular phylogeny of Sensitibillini and analyse the evolutionary pattern of their genitalia. Afrotrogla and Neotrogla did not form a monophyletic clade, and their female penis structures are significantly different, suggesting two independent origins of the female penis within Sensitibillini. In Neotrogla , the species that has a simple female penis is embedded among species that have an elaborate penis, and detailed structures of the female penis elaborations are in exact agreement among species, suggesting a secondary simplification of the female penis. A correlated evolutionary pattern between male and female genitalia was also detected. This coevolution of genitalia may suggest that sexual conflict or cryptic ‘male’ choice drove the diversity of the female penis, as is the case of male penile diversity in animals with conventional genitalia.

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Phylogenetic relationships among extant families in the suborder Trogiomorpha (Insecta: Psocodea: 'Psocoptera') were inferred from partial sequences of the nuclear 18S rDNA and Histone 3 and mitochondrial 16S rDNA genes. Analyses of these data produced trees that largely supported the traditional classification; however, monophyly of the infraorder Psocathropetae ( = Psyllipsocidae + Prionoglarididae) was not recovered. Instead, the family Psyllipsocidae was recovered as the sister taxon to the infraorder Atropetae ( = Lepidopsocidae + Trogiidae + Psoquillidae), and the Prionoglarididae was recovered as sister to all other families in the suborder. Character states previously used to diagnose Psocathropetae are shown to be plesiomorphic. The sister group relationship between Psyllipsocidae and Atropetae was supported by two morphological apomorphies: the presence of a paraproctal anal spine and an anteriorly opened phallosome. Based on these sequence data and morphological observations, we propose a new classification scheme for the Trogiomorpha as follows: infraorder Prionoglaridetae (Prionoglarididae), infraorder Psyllipsocetae (Psyllipsocidae), infraorder Atropetae (Lepidopsocidae, Trogiidae, Psoquillidae).

We report a functional switching valve within the female genitalia of the Brazilian cave insect Neotrogla. The valve complex is composed of two plate-like sclerites, a closure element, and in-and-outflow canals. Females have a penis-like intromittent organ to coercively anchor males and obtain voluminous semen. The semen is packed in a capsule, whose formation is initiated by seminal injection. It is not only used for fertilization but also consumed by the female as nutrition. The valve complex has two slots for insemination so that Neotrogla can continue mating while the first slot is occupied. In conjunction with the female penis, this switching valve is a morphological novelty enabling females to compete for seminal gifts in their nutrient-poor cave habitats through long copulation times and multiple seminal injections. The evolution of this switching valve may have been a prerequisite for the reversal of the intromittent organ in Neotrogla.