Systematics of the pseudocentron-group of Megachile (Megachilidae: Megachilini) and its relevance to the biogeography of neotropical bees

Author(s)

Diego Alexander Guevara Farias

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (PCARP/BC)
• Defense date: 2025-09-26

Examining board members

Eduardo Andrade Botelho de Almeida; Gabriel Augusto Rodrigues de Melo; Daniele Regina Parizotto

• Advisor: Eduardo Andrade Botelho de Almeida

Abstract

Leaf-cutting bees (Apoidea: Megachilidae: Megachile) include important pollinators of wild and cultivated plants. Their common name stems from the fact that their females cut leaves and roll them to line their brood cells when building nests. Megachile is the largest genus of Megachilidae (approximately 1,500 species worldwide) and the most species-rich in Brazil (145 of the 340 Brazilian species of Megachilidae belong to this genus), which poses challenges to the taxonomy of his taxon. Recent phylogenetic hypotheses shed light on the limits of subgenera and enabled the recognition of species- and subgenus-groups, such as the Pseudocentrongroup, comprising seven subgenera: M. (Acentron), M. (Grafella), M. (Leptorachis), M. (Leptorachina), M. (Melanosarus), M. (Moureapis), and M. (Pseudocentron). In this Dissertation, the evolution and spatiotemporal historical patterns of the Pseudocentron-group of Megachile were investigated, starting with the proposal of a phylogenetic hypothesis based. Our results recovered allsubgenera ofthe Pseudocentron-group as natural groups, except for M. (Acentron) and M. (Pseudocentron). We analyzed the morphological variation of the mandibular apex of females and some secondary sexual charactersin malesfrom an evolutionary perspective, which supports different lineages of the Pseudocentron-group. Overall, the mandibular character transformations of the female mandible did not play a significant role in the phylogenetic pattern, as their importance as diagnostic characteristics for recognition and delimitation of taxa. Additionally, we identified that at least four faunal exchange events shaped the diversification of the Pseudocentron-group during the late Miocene between northern and southern areas of the Americas. These interchanges likely took place between the North America + Chocó region and the remainder of South America, coinciding with similar patterns observed in other bee lineages, as well as with geological events such as the formation of the Isthmus of Panama. (AU)

• FAPESP's process: 22/15636-7 - Systematics of the Pseudocentron-group of Megachile (Megachilidae: Megachilini) and relevance to the biogeography of neotropical bees
• Grantee: Diego Alexander Guevara Farías
• Support Opportunities: Scholarships in Brazil - Master