Sperm morphology and phylogeny of lagriids (Coleoptera, Tenebrionidae)

•In tenebrionids, the flagellar components offer good diagnostic characters.•Sperm of Lagria villosa exhibit a strong morphological similarity to those of tenebrionids.•The sperm morphology support lagriids as a subfamily of Tenebrionidae.

The systematics of tenebrionids remain unclear, principally at the subfamily level, as is the case of the Lagriinae. Considering that sperm morphology has contributed to the various insect group phylogenies, in this work we describe the structure and ultrastructure of these cells in Lagria villosa. Sperm in this species exhibit a strong morphological similarity to those of Tenebrio molitor and Tribolium castaneum, the only two species of Tenebrionidae with previously described sperm. In tenebrionids, the flagellar components offer good diagnostic characters, e.g. the symmetry of mitochondrial derivatives in L. villosa differentiates sperm of this species from those of Te. molitor and Tr. castaneum. However, the lateral association of the nucleus with flagellar components, the form of accessory bodies, and the presence of material connecting the axoneme to the accessory bodies and mitochondrial derivatives indicate that the three species form a sister group. Therefore, the sperm morphology of L. villosa support lagriid beetles as a subfamily (Lagriinae) of Tenebrionidae.

Graphical abstractSchematic reconstructions. Acrosome-nucleus (A, B) and nucleus-flagellum (C-F) transitions in longitudinal sections, and flagella in cross-sections (G-K). p, perforatorium; n, nucleus; ax, axoneme. A, D and I = Lagria villosa; B, E and J = Tenebrio molitor (from: Baccetti et al., 1973); C and H = Cosmopolites sordidus (from: Lino-Neto & Dolder, 1995); F and K = Tribolium castaneum (from: Dias et al., 2010); G = Gastrophysa viridula (from: Baccetti and Daccordi, 1988). Obs. No significance should be attached to branch lengths.Figure optionsDownload full-size imageDownload as PowerPoint slide