On the Structure of the Aedeagus in Shield Bugs (Heteroptera, Pentatomidae): 1. Subfamilies Discocephalinae and Phyllocephalinae

The paper starts a series of publications on the structure of the aedeagus Pentatomidae and its possible taxonomic significance. The structure of the aedeagus in the entire family is discussed in brief. The structure of the aedeagus in 14 species of Discocephalinae and 13 species of Phyllocephalinae is described. The Discocephalinae strongly differ from other subfamilies in the absence of differentiation in the vesica and conjunctiva and in their strong sclerotization. In Discocephalinae, the structure of the aedeagus is a valuable taxonomic character at the ge- neric and suprageneric levels. In Phyllocephalinae, by cont rast, all the species possess the common basic plan of the structure of the aedeagus. It can be treated as an autapomorphy of the group, but makes the use of this character insufficient for the phylogenetic reconstruction of the subfamily. The structure of the male genitalia is actively used in the taxonomy of Heteroptera, and of shield bugs in particular. This complex of characters is used not only for distinguishing closely related species, but also in the supergeneric classification. First of all, this is true for the structure of the gen ital capsule and parameres, whereas structures of the aedeagus are used to a sig- nificantly lesser extent. It is mainly stipulated by the complicated structure of the aedeagus in Pentatomi- dae, in particular, by the presence of a complex of membranous lobes and sclerotized appendages, densely packed in the sclerotized theca, which are fully straightened only during copulation. The main goal of the present work was to study the structure of the fully straightened aedeagus in Pentatomidae and to reveal characters important for the supergeneric diag- nostics of the group. The inner membranous structures of the aedeagus were straightened due to the difference in the osmotic pressure (Kerzhner and Konstantinov, 1999) and by their hydraulic blowing (Gapon, 2001). Preparation of aedeagi and drawing were performed according to the standard methods. The vast basic collection of the Zoological Institute of the Russian Academy of Sci- ences (ZIN) was used as a source of the material for examination. The terms "proximally," "distally," "api- cally," and "basally' in relation to the structures of the aedeagus are applied for the fully stretched organ. In shield bugs, the position of the aedeagus in relation to the body axis somewhat varies. For standardization of descriptions, the side adjoining the ventral wall of the genital segment during copulation is designated as the ventral surface of the aedeagus. The aedeagus is pic- tured in dorsal, ventral, and lateral views correspond- ing to each other in different species. In all the cases, the scale is 0.2 mm. The terminology of parts of the aedeagus in Heter- optera, proposed by Singh-Pruthi (1925) and later supplemented and adopted in relation to shield bugs by Baker (1931), McDonald (1961, 1966), and Gross (1975, 1976), is widespread and at present is virtually stable. It is also used in the present work, with several necessary additions.