A comparative study of the proventricular structure in corbiculate apinae (Hymenoptera, Apidae)

Abstract

The present study compares the proventricular structure, analyzed under scanning electronic microscope (SEM), among tribes of corbiculate Apinae. Fifty-one species of stingless bees (Meliponini), one species of honeybee (Apini), three species of bumblebees (Bombini) and seven species of orchid bees (Euglossini), were analyzed as in-group, and one species of sphecid wasp (Sphecidae) and two species of Halictidae bees, as out-groups. The proventricular bulb presents a basic morphology pattern similar to that of other Hymenoptera such as ants and wasps, being a symplesiomorphy for bees. The shape of proventricular folds constitutes a synapomorphy for Meliponini and an autapomorphy for Apini. The shape of hair-like projections of the cuticle that lines the proventriculus is a synapomorphy for Meliponini and Apini. These proventricular data corroborate the monophyly of the tribe Meliponini and the hypothesis that recognizes only one tribe for stingless bees. In addition, Meliponini+Apini constitutes a monophyletic group and Bombini+Euglossini another monophyletic group. The results confirm that internal morphology is a character that can be used in studies of the phylogeny in insects and the use of SEM as a powerful tool in these analyses.