The metendosternite and penile flagellum: two unexplored character systems of pleasing fungus beetles (Coleoptera: Erotylidae)

Abstract

Abstract Erotylidae (Cucujoidea) are currently divided into six subfamilies, which are regarded as monophyletic. However, there are doubts on the monophyly of lower ranked taxa within Erotylidae, including its most diverse tribe (Tritomini) and the highly diverse genus Mycotretus (Tritomini). The next steps in phylogenetic studies on these taxa rely on better sampling and on studies of unexplored character sets. Here, we conduct a comparative morphological study of the metendosternite and the penile flagellum within Erotylidae, with emphasis on Tritomini and Mycotretus, establishing a naming system for these structures. Representatives of 56 species belonging to all subfamilies of Erotylidae were analysed. A total of 17 genera and 45 species of Tritomini were selected, of which 21 species were Mycotretus. A total of 17 characters (eight of the metendosternite and nine of the penile flagellum) with potential phylogenetic value were recognized. Within Tritomini there is evidence of phylogenetic signal for the presence or absence of the metendosternal lamina at the generic level and above. On the other hand, the penile flagellum may be more informative for levels below the genus and morphological features of the flagellar ‘head’ seem to have phylogenetic signal for groups of potentially related species of Mycotretus.