A revision of Peckena Gnaspini, 1996 with description of the second species and Amplexella Gnaspini, 1996 (Coleoptera: Leiodidae: Cholevinae: Ptomaphagini), using scanning electron microscopy as a key tool to understand the evolution of aedeagal morphology

Abstract

We revisit the diagnosis and evolution of aedeagal morphology in the tribe Ptomaphagini using scanning electron microscopy (SEM) images, here focusing on the genera Peckena Gnaspini, 1996 and Amplexella Gnaspini, 1996. In a revision of the genus Adelopsis Portevin, 1907 (previously with a non-monophyletic status), and based on a phylogenetic analysis, four new genera (with Neotropical distribution) were described in 1996. Among them, Peckena was based on a single species (from Peru) with a ventral opening as the plesiomorphic state of the aedeagus (whereas all other species in the subtribe Ptomaphagina have a dorsal opening); and Amplexella, based on two species (from Venezuela), with a typical aedeagus bearing an extremely long flagellum. SEM Images of the aedeagus of the species of the genus Peckena showed a dorsally visible notch cutting the left side of the aedeagus, as is the condition in the other neotropical ptomaphagines, but, still, the opening is indeed ventral. Based on that new information, we recognized and describe one new Brazilian species tentatively assigning it to the until now monotypic genus Peckena: Peckena verrucosa sp. n., from São Paulo and Minas Gerais states. There is a large geographical distance between the two species, placed on opposite sides of South America, with important phylogenetic and biogeographic implications. SEM images of the aedeagus of the species of the genus Amplexella showed that the opening of the aedeagus cuts the apical left side through a very narrow slit diagonally, and the dorsal opening is small and defined by a space between the apices of the left and right lobes, unnoticeable because it is obliterated by the thick flagellum coming out of it.