Endophallus inflation: A potential taxonomic tool for the subfamily Scolytinae (Coleoptera: Curculionidae)

Abstract

The taxonomy of the subfamily Scolytinae has traditionally been based on external morphological attributes corresponding to the elytral declivity, head, and pronotum. Some traits from the general morphology of the aedeagus and spermatheca have been proposed in scarce genera. In this study, we explore and improve a technique of endophallus inflation to apply it in Scolytinae members and to describe its morphology for the first time in 16 species from Dendroctonus Erichson, Ips DeGeer, and Phloeosinus Chapuis. These taxa display differences in the attachment types of endophallus and two distinct inflation and retraction mechanisms. Our results support the use of the internal sac as a taxonomic feature in Scolytinae because each tribe, genus, and species display a particular morphological pattern. The results also indicate use of the internal sac for Dendroctonus taxonomy supports phylogenetic inferences.