Male reproductive system and spermatozoa morphology of Ephemeroptera (Insecta) and evaluation of the potential in phylogenetic analysis

Author(s)

Pedro Vale de Azevedo Brito

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2012-02-23

Examining board members

Mary Anne Heidi Dolder; Sônia Nair Báo; Cléber Macedo Polegatto; Jose Lino Neto; Elidiomar Ribeiro da Silva

• Advisor: Mary Anne Heidi Dolder; Frederico Falcão Salles

Abstract

Ephemeroptera species are the oldest living winged insects. Their nymphs are aquatic and the adults are short living, dying just after mating. At the present, there are still some doubts about the phylogenetic relationships between Ephemeroptera and the other Pterygota. The morphology of the male reproductive systems and of the spermatozoa is useful to furnish data for phylogenetic studies. However, there are few studies on this subject for Ephemeroptera. This study analyzes the morphology of the male reproductive system and of the spermatozoa of Brazilian Ephemeroptera species.. Species from ten Ephemeroptera families are found in Brazil. In the present study we analyzed the male reproductive system of six species from five families. We also analyzed the sperm morphology of 17 species from nine families. The male reproductive systems analyzed were very similar in the different species, with no accessory glands or specialized organs for sperm storage. However, the intrinsic musculatures of the sperm ducts have different organization patterns, probably related to differences in the reproductive physiology of each species. Greater morphological variation was observed among the spermatozoa. Species from Leptophlebiidae family have aflagellate and immotile spermatozoa. Species from the other families have mobile and flagellate spermatozoa. The organization of the axoneme was the same in all species, with the 9+9+0 microtubule pattern, typical for this insect group. Only the accessory microtubules vary between the 13+7 and the 13+0 subunit patterns. The flagella are characterized by the presence of only one mitochondrion along the flagellum. The accessory bodies morphology may vary between the species and it seems to be correlated to the organization of the mitochondrial cristae and the accessory bodies morphology. The acrosomal vesicles have morphological variations that must be related to differences in the egg chorion thickness. A centriolar adjunct is observed at the flagellum anterior region of the spermatozoa. This structure was thought to be absent in the Ephemeroptera spermatozoa. One species studied has its nucleus laterally associated to the flagellum. Our results suggest that the spermatozoa of Ephemeroptera have enough morphological variation to furnish useful data for future phylogenetic studies. However, more species, representing different groups of the order must be studied, increasing the scope of these studies. Also some questions, such as the origin of the accessory bodies of Ephemeroptera must be further studied (AU)

• FAPESP's process: 07/07522-1 - Morphology of the reproductive systems and the spermatozoa of Ephemeroptera (Insecta) and analysis of their phylogenetic potential
• Grantee: Pedro Vale de Azevedo Brito
• Support Opportunities: Scholarships in Brazil - Doctorate