Identification of the odoriferous secrecy of Gonyleptes horridus (Kirby, 1819) (Arachnida: Opiliones: Gonyleptidae) and its impact on Gonyleptinae's systems

Abstract

Harvestmen belong to Arachnida, and it is the third-largest order, after Acari, which includes mites and ticks, and Araneae, which is composed by spiders. Harvestmen harbor 6000 described species and they are found in almost all continents. The order is composed of four suborders, Laniatores being the largest in a number of species (approximately 4000), displaying a vast variety when it comes to behavior, production of chemical compounds, and morphology. Laniatores harvestmen inhabit almost all of South America and it is the most studied regarding the aspects above. Regarding defense, harvestmen display a rather diverse repertoire, such as the release of secretions to stun predators, retaliation, and feigning death (thanatosis), just to name a few. The odoriferous secretion can vary in its composition in Laniatores. The identification of such compounds can contribute as a source of natural products as well as a source of characters for phylogenetic inferences. A species recurrently used in comprehensive phylogenetic analyses is Gonyleptes horridus (Kirby, 1819). This species is important because it is the type species of Gonyleptes, which in turn names the subfamily Gonyleptinae, which is polyphyletic and the second largest in the number of species. Despite its taxonomic importance, the defensive secretion of G. horridus remains unknown. In this work, we will research and characterize the odoriferous secretion of G. horridus, which inhabits Rio de Janeiro. Considering that Gonyleptinae is polyphyletic, the identification of the compounds of the odoriferous secretion of G. horridus might contribute as a source of characters in future phylogenetic inferences to propose monophyletic groups, allowing further evolutionary study in the group.