Acta Zoologica. 2019;00:1–12. wileyonlinelibrary.com/journal/azo | 1 © 2019 The Royal Swedish Academy of Sciences 1 | INTRODUCTION Megaloptera is currently represented by 35 genera with ap- proximately 380 extant species (Cover & Resh, 2008; Engel, Winterton, & Breitkreuz, 2018; Theischinger, 1991) distrib- uted in two families, Sialidae and Corydalidae. In contrast to Sialidae, Corydalidae is represented by large insects, whose corporeal sizes, in general, exceed 25 mm in length. Most of the species of Megaloptera belong to Corydalidae, which is divided into Chauliodinae (around 130 species) and Corydalinae (around 145 species). Corydalinae is the most di- versified group of Megaloptera also in the Neotropics, where 56 species have been described in the genera Corydalus Latreille, Chloronia Banks and Platyneuromus van der Weele Received: 18 March 2019 | Revised: 24 September 2019 | Accepted: 25 September 2019 DOI: 10.1111/azo.12312 ORIGINAL ARTICLE Sperm Ultrastructure of corydalid Corydalus diasi Navás (Megaloptera, Neuropterida, Insecta) with phylogenetic considerations Lívia Cuquetto‐Leite 1 | Aline Barbosa 2 | Frederico Falcão Salles 3 | Karina Carvalho Mancini 2 1 Department of Structural and Functional Biology, Campinas State University (UNICAMP), Campinas, São Paulo, Brazil 2 Department of Agrarian and Biological Sciences, Federal University of Espírito Santo (UFES), São Mateus, Espírito Santo, Brazil 3 Department of Entomology, Federal University of Viçosa (UFV), Viçosa, Minas Gerais, Brazil Correspondence Lívia Cuquetto‐Leite, Department of Structural and Functional Biology, Biology Institute, 13083‐865, Campinas State University (UNICAMP), São Paulo, Brazil. Email: livia.cuquetto@gmail.com Funding information Conselho Nacional de Desenvolvimento Científico e Tecnológico; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior Abstract Spermatozoa of the Megaloptera Corydalus diasi (Corydalidae) showed a two‐ layered acrosome, similar to Raphidioptera, but different from the acrosomal ar- rangement in Ascalaphidae, Coniopterygidae and Myrmeleontidae (Neuroptera families) and Sialidae (Megaloptera). Also, the acrosomal shape differs from both Raphidioptera and Neuroptera examined so far. The nucleus is cylindrical with con- densed chromatin, resembling the sperm of Sialidae, Raphidioptera and Neuroptera. The transition region of C. diasi does not have the nucleus surrounded by centri- olar microtubules, and thus, it differs from Sialidae, whose character has been pre- viously considered a synapomorphy between Megaloptera and Raphidioptera. The flagella analysed here possess a 9 + 9 + 2 axoneme arrangement, two elongated circular mitochondrial derivatives and triangular accessory bodies, which are also re- ported in Raphidioptera. In summary, there are numerous sperm differences between Corydalidae and Sialidae, besides several characters shared between Corydalidae and Raphidioptera. However, several of these similarities appear to be plesiomorphisms rather than synapomorphies. Additionally, this is the first spermatic description for Corydalidae and the second for Megaloptera order. Therefore, considering the num- ber of genres that comprise this family and the lack of spermiocladistics studies for Corydalidae, we recommended that new studies on the field should be performed to better understand the sperm pattern within the Corydalidae genus. KEYWORDS Corydalidae, morphology, phylogeny, spermatozoa