The spermatheca in the genus Dendroctonus (Curculionidae: Scolytinae): morphology, nomenclature, potential characters for taxonomic use and phylogenetic signal

In most members of the genus Dendroctonus, the usefulness of the spermatheca for taxonomic purposes has not been evaluated in depth; therefore, the aim of this study is to describe and compare the elements that integrate the female reproductive apparatus among Dendroctonus species, clarify their nomenclature and evaluate their interspecific variation to propose useful characteristics for their identification. In addition, we evaluated whether there is a structure between the shape of the receptacle and the phylogenetic relatedness of the species. The spermatheca consists of a sperm duct, a receptacle, and a gland; of these elements, the receptacle is the most taxonomically informative structure. The most closely related species of the D. frontalis complex show wide intraspecific variation in the shape and size of this structure, which precludes recognition of diagnostic features. However, there are differences among species groups in both shape and size in less closely related species such as D. approximatus, D. mexicanus, D. micans, D. parallelocollis and D. rhizophagus. A phylogenetic signal was detected in receptacle shape, and patterns of morphological similarity and phylogenetic relatedness of species were evident in the D. frontalis complex.