The Structure of the Endophallus Is a New Promising Feature and a Key to Study of Taxonomy of the Subgenus Metallotimarcha of the Genus Timarcha (Coleoptera, Chrysomelidae) in the Caucasus

SIMPLE SUMMARY: Knowing the correct names of animal species is especially important nowadays; information is posted on the internet, and is available by using keywords. To establish the valid species and subspecies names, it is necessary to research a large amount of material and literature. Of particular importance is the study of type specimens—that is, those specimens for which the names were first established. In the subgenus Metallotimarcha, of the leaf-beetle genus Timarcha, the external structure of beetles and the shape of the male aedeagus do not allow precise identification of the species. The search for new characters has led to the need to study the internal structure of the male aedeagus. As a result, clear species boundaries of T. metallica, T. corinthia, and T. hummelii have been found. It was established that T. armeniaca and T. hummelii starcki are the synonyms of T. hummelii hummelii. ABSTRACT: A comparative morphological study of the members of the subgenus Metallotimarcha revealed that Caucasian Timarcha hummelii is a separate species, which differs from European members of the subgenus (T. metallica, T. corinthia, T. gibba) by the internal structure of male aedeagus, namely, manubrium of the endophallus. Morphology of manubrium is described for all species of the subgenus. External characters and the shape of male aedeagus do not permit separating the members of the subgenus distinctly. Examination of both external characters and endophallus structure in the specimens from the Caucasus revealed that T. armeniaca and T. hummelii starcki are the synonyms of T. hummelii hummelii, but not separate species or subspecies. Neotypes of T. hummelii and T. armeniaca are designated. Syntypes of T. hummelii starcki are examined. The key to the species for the subgenus Metallotimarcha is compiled.