Morphology of the male reproductive tract in the water scavenger beetle Tropisternus collaris Fabricius, 1775 (Coleoptera: Hydrophilidae)

Vinícius Albano Araújo,Igor Luiz Araújo Munhoz,José Eduardo Serrão

doi:10.1590/1806-9665-rbent-2021-0012

Abstract

ABSTRACT Members of the Hydrophilidae, one of the largest families of aquatic insects, are potential models for the biomonitoring of freshwater habitats and global climate change. In this study, we describe the morphology of the male reproductive tract in the water scavenger beetle Tropisternus collaris. The reproductive tract in sexually mature males comprised a pair of testes, each with at least 30 follicles, vasa efferentia, vasa deferentia, seminal vesicles, two pairs of accessory glands (a bean-shaped pair and a tubular pair with a forked end), and an ejaculatory duct. Characters such as the number of testicular follicles and accessory glands, as well as their shape, origin, and type of secretion, differ between Coleoptera taxa and have potential to help elucidate reproductive strategies and the evolutionary history of the group.

Highlights

Coleoptera is the most diverse group of insects in the current fauna, with about 400,000 described species and still thousands of new species waiting to be discovered (Slipinski et al, 2011; Kundrata et al, 2019)
This study aimed to describe the anatomy and histology of the male reproductive system in the hydrophilid Tropisternus collaris Fabricius, 1775, in order to contribute to the knowledge of reproductive biology and evolutionary history of the Coleoptera
The reproductive tract of sexually mature T. collaris males comprised a pair of testes, vasa efferentia, vasa deferentia, seminal vesicles, two pairs of accessory glands, and an ejaculatory duct (Fig. 1A, 1B)

Summary

Introduction

Coleoptera is the most diverse group of insects in the current fauna, with about 400,000 described species and still thousands of new species waiting to be discovered (Slipinski et al, 2011; Kundrata et al, 2019). Aquatic beetle faunas have been widely sampled in ecological studies focused on biomonitoring and species richness These relatively large insects are sensitive to environmental changes, show wide distribution, can be sampled, and occupy different guilds in aquatic and semiaquatic ecosystems (Short and Fikáček, 2011; Short, 2018). Because of these characteristics, aquatic beetles have been proposed as potential bioindicators of water quality and global climate change impacts (Guareschi et al, 2012; Kaboré et al, 2016)

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